Durham E-Theses
Nitrogen ligands in transition metal carbonyl systems
Payling, Catherine A.
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Payling, Catherine A. (1969)
Nitrogen ligands in transition metal carbonyl systems, Durham theses,
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NITROGEN LIGANDS I N TRANSITION METAL CARBONYL SYSTEMS
by
C a t h e r i n e A. P a y l i n g , B . S c .
( S t . Mary's
A thesis
College)
s u b m i t t e d t o t h e U n i v e r s i t y o f Durham f o r t h e
d e g r e e of D o c t o r
of Philosophy
J u l y 1969
MEMORANDUM
The
work d e s c r i b e d i n t h i s t h e s i s was
University
of Durham between O c t o b e r 1966
h a s not been s u b m i t t e d
work of t h e a u t h o r
Part
c a r r i e d out i n t h e
and J u l y 1969.
f o r any o t h e r d e g r e e and
It
i s the o r i g i n a l
e x c e p t where acknowledged by r e f e r e n c e .
o f t h i s work h a s been p u b l i s h e d i n t h e A b s t r a c t s of
the 4 t h I n t e r n a t i o n a l Conference
Bristol, July
1969.
on O r g a n o m e t a l l i c
Chemistry,
ACKNOWLEDGEMENTS
I
should
like
to express
my s i n c e r e g r a t i t u d e t o
Dr. M. K i l n e r , under whose s u p e r v i s i o n t h i s r e s e a r c h was
c a r r i e d out,
for h i s continual advice
and encouragement.
My t h a n k s a r e a l s o due t o Dr. K. Wade f o r many h e l p f u l
discussions.
I
am i n d e b t e d
maintenance
to the Science Research Council
for a
grant.
C.A.
Payling
Durham, 1969.
SUMMARY
A t t e m p t s t o i n t r o d u c e some n i t r o g e n l i g a n d s i n t o t r a n s i t i o n
c a r b o n y l and
non-carbonyl systems
R e a c t i o n of t h e l i t h i u m and
metal
are described.
t r i m e t h y l s i l y l d e r i v a t i v e s of
diphenyl-
ketimine with b i s ( t r i p h e n y l p h o s p h i n e ) c o b a l t ( H ) d i c h l o r i d e gives
(Ph C=NH) Co
2
i : C
2
the expected
Cl
2
(Ph C=NH)(PPh ) C o
2
i : C
3
Cl
2
respectively, rather
d e r i v a t i v e s c o n t a i n i n g the a n i o n i c k e t i m i n o
I I
(Ph C=NH) Co Cl
2
and
2
2
and
I I
(Ph C=NH) Ni Cl
2
2
2
than
ligand.
a r e formed by d i r e c t r e a c t i o n of
the n e u t r a l l i g a n d w i t h the b i s ( t r i p h e n y l p h o s p h i n e ) m e t a l d i c h l o r i d e
complexes.
The
c o b a l t complex h a s a t e t r a h e d r a l c o n f i g u r a t i o n , w h i l e
n i c k e l d e r i v a t i v e has a polymeric
I I
complex, N i C l . 2 T H F
2
octahedral structure.
The
the
octahedral
i s s u r p r i s i n g l y formed from ( P h ^ j P ^ N i ^ C l g and
THF.
R e a c t i o n s of d i p h e n y l k e t i m i n o d i p h e n y l m e t h y l c h l o r i d e and i t s
Grignard d e r i v a t i v e with s e v e r a l metal
carbonyl
non-carbonyl
The
compounds a r e d e s c r i b e d .
two
systems
new
and
some n i c k e l
manganese c a r b o n y l
c o m p l e x e s M n C c O ^ C P t ^ C N C P t ^ ) and B r M n ( C O ) ^ ( P h C N C P h ) a r e d i s c u s s e d i n
2
terms of p o s s i b l e t y p e s o f m e t a l - l i g a n d b o n d i n g , and
related
2
a pseudo-allylic,
s t r u c t u r e , i s p r o p o s e d f o r e a c h compound.
D i f f e r e n c e s i n behaviour
o f e t h y l e n e i m i n e t o w a r d s Group V I
h e x a c a r b o n y l s and manganese p e n t a c a r b o n y l
r i n g o p e n i n g and
bromide a r e o b s e r v e d .
MnCcOO^CAz^Br
}
metal
Ready
p o l y m e r i s a t i o n of t h e l i g a n d o c c u r s t o g i v e m e t a l
d e r i v a t i v e s , but a manganese c a r b o n y l bromide d e r i v a t i v e ,
formed.
or
c o n t a i n i n g the l i g a n d w i t h the r i n g
still
carbonyl
probably
intact, i s also
A v a r i e t y o f r e a c t i o n s between n i t r i t e
systems
but
are described.
the complex
s a l t s and m e t a l
carbonyl
U n s t a b l e s p e c i e s a r e formed i n t h e s e r e a c t i o n s ,
rt-CpFeCCO^NC^
c a n be i d e n t i f i e d s p e c t r o s c o p i c a l l y ,
though i t i s n e v e r i s o l a t e d f r e e of i t s d e c o m p o s i t i o n
products.
e v i d e n c e of f o r m a t i o n o f n i t r o s y l c o m p l e x e s i n t h e s e r e a c t i o n s i s
described.
Some
CONTENTS
Page
CHAPTER
A,
Nitrogen Ligands
ONE
G e n e r a l I n t r o d u c t i o n , 1; B, The
6; D,
Carbonyl
Systems
1
I n e r t Gas R u l e , 2; C,
Syntheses,
Survey
G, C a r b o n y l
Complexes i n O r g a n i c
of Compounds: 1, T i t a n i u m and Vanadium, 19;
Tungsten,
20;
2,
3 a , Manganese, 38;
Rhenium and
T e c h n e t i u m , 48; 4 a , I r o n , 50; 4b, Ruthenium
Osmium, 68;
5, C o b a l t , Rhodium and
P a l l a d i u m and
CHAPTER TWO
F,
16;
Chromium, Molybdenum and
A,
Bonding,
I n f r a r e d S p e c t r a , 8; E , Methods of P r e p a r a t i o n , 10;
R e a c t i o n Mechanisms, 14;
H,
i n Metal
Platinum,
3b,
and
I r i d i u m , 70; 6, N i c k e l ,
78.
Azomethine D e r i v a t i v e s of T r a n s i t i o n M e t a l s
83
I n t r o d u c t i o n , 83; B, N o n c a r b o n y l C o b a l t C o m p l e x e s , 87;
C, N o n c a r b o n y l N i c k e l S y s t e m s , 100;
Derivatives,
CHAPTER THREE
Carbonyl
106.
R e a c t i o n s of D i p h e n y l k e t i m i n o d i p h e n y l m e t h y l c h l o r i d e
w i t h T r a n s i t i o n Metal
CHAPTER FOUR
D, C o b a l t
118
Complexes
R e a c t i o n s of t h e G r i g n a r d D e r i v a t i v e of D i p h e n y l ketiminodiphenylmethylchloride with Transition
138
Complexes
CHAPTER F I V E
Some A z i r i d i n e D e r i v a t i v e s of T r a n s i t i o n
Carbonyls
Metal
Metal
152
Page
CHAPTER S I X
R e a c t i o n s of N i t r i t e S a l t s w i t h T r a n s i t i o n M e t a l
167
Carbonyls
Appendix 1
E x p e r i m e n t a l D e t a i l s and S t a r t i n g M a t e r i a l s
Appendix 2
Instrumentation
Appendix 3
A n a l y t i c a l Methods
References
i
i i i
v
CHAPTER
ONE
Nitrogen Ligands i n Metal Carbonyl
Systems
-1-
A.
General
The
metal
Introduction
last
decade h a s
seen a r a p i d expansion
carbonyl chemistry.
The
carbonyls
i n the f i e l d
themselves
as have the a n i o n i c c a r b o n y l m e t a l l a t e s ^ , metal
of
transition
12
'
have been r e v i e w e d
3
,
5
o l e f i n e complexes**' ^,
g
p e r f l u o r o a l k y l metal
complexes
, i t - c y c l o p e n t a d i e n y l and
d e r i v a t i v e s ^ ' ^ , Lewis base metal
metal
carbonyls
12
n-arene
carbonyl complexes^, sulphur
, s u b s t i t u t i o n products
o f the Group V I B m e t a l
metal
containing
carbonyls
13
,
14
photochemical
s u b s t i t u t i o n s on m e t a l
c a r b o n y l s and
their derivatives
the k i n e t i c s and mechanisms of s u b s t i t u t i o n r e a c t i o n s o f m e t a l
complexes.^"*
,
The
.
or a book i n
L
In
two
u s e of m e t a l
i
16
volumes.
this chapter,
carbonyls i n organic
t r a n s i t i o n metal
n i t r o g e n atom bonded d i r e c t l y
carbonyl
s y n t h e s e s i s the s u b j e c t
carbonyl d e r i v a t i v e s containing a
t o the m e t a l
w i l l be
reviewed.
compounds c o n t a i n i n g s i m p l e o r g a n o n i t r o g e n m o l e c u l e s
I n the
such a s amines,
n i t r o g e n atom d o n a t e s i t s l o n e p a i r of e l e c t r o n s to the m e t a l ,
a a-bond, b u t
involving
t h e r e c a n be no
f i l l e d metal
and
s t r e n g t h e n i n g o f t h i s bond by
thus
the
forming
jt-bonding
d - o r b i t a l s , a s t h e n i t r o g e n atom, b e i n g
a first
row
e l e m e n t , l a c k s s u i t a b l e o r b i t a l s o f low enough e n e r g y to p a r t i c i p a t e i n
this
type of bonding.
unsaturated
system,
However, i f t h e n i t r o g e n atom i s p a r t of
f o r example an a r o m a t i c
can a c t a s a j t - a c c e p t o r =
available for overlap with
i n t e r a c t i o n may
be
The
ring,
then
an
t h e l i g a n d a s a whole
empty T t - o r b i t a l s o f the u n s a t u r a t e d
the non-bonding m e t a l
p o s s i b l e w h i c h would r e s u l t
o r b i t a l s and
system
are
so a s y n e r g i c
i n a s t r e n g t h e n i n g of
the
-2-
M-L
bond.
P a r t i c u l a r r e f e r e n c e w i l l be made to c o m p l e x e s where t h i s
o f i n t e r a c t i o n i s p o s s i b l e , a s the work d e s c r i b e d i n t h i s
these
concerns
t y p e s of l i g a n d s .
No
a t t e m p t h a s been made i n the r e v i e w
metal n i t r o s y l
h a s r e c e n t l y been r e v i e w e d .
The
I n e r t Gas
One
of
chemistry
transition
17 18
'
g e n e r a l l y a p p l i c a b l e concepts
the m e t a l c a r b o n y l s and
a t o m i c number" o r " r a r e g a s " r u l e .
That
the
"effective
i s , the c e n t r a l m e t a l atom
a c h i e v e s a f o r m a l l y c l o s e d s h e l l , or " i n e r t " gas
s i m p l e r u l e h a s been v e r y
in
t h e i r d e r i v a t i v e s i s the
a number of a d d i t i o n a l e l e c t r o n s from i t s s u r r o u n d i n g
accepts
l i g a n d s so t h a t i t
configuration.
This
s u c c e s s f u l i n p r e d i c t i n g the s t o i c h i o m e t r y
of
c o m p l e x e s , so much so t h a t the few compounds w h i c h do n o t conform to
rule are s t i l l
The
considered
as
the
"exceptions".
r u l e c a n be a p p l i e d w h a t e v e r t y p e s of l i g a n d s a r e i n v o l v e d ,
many compounds can be r e g a r d e d
counting
procedure.
i n at least
four carbonyl
groups ( 4 x 2
anions
e l e c t r o n s ) and
In either case
two
t h e r e i s no.
two
I*
radicals
e l e c t r o n s ) , or ( i i ) F e
the four carbonyl
n e t c h a r g e on
but
ways f o r t h i s e l e c t r o n
T h u s , the compound F e C C O ) ^ ^ may
composed o f ( i ) Fe° ( 8 e l e c t r o n s ) ,
( 2 x 2
and
Rule
the most u s e f u l and
of
to i n c l u d e a l l the
compounds, a s t h e s e form a s e p a r a t e c l a s s of compounds,
their chemistry
B.
thesis
type
be
considered
( 2 x 1
X
i
be
e l e c t r o n s ) and
(6 e l e c t r o n s ) ,
groups ( 4 x 2
the complex, and
to
two I ~
electrons).
the
t o t a l number
-3-
of e l e c t r o n s i s 18.
The
apparent d i f f e r e n c e i n formal
the m e t a l atom h a s
little
r e a l meaning i n most c a s e s i n w h i c h s t r o n g
l i g a n d bonding e x i s t s , although a c c o r d i n g
state,
the i o d i n e a n i o n
o x i d a t i o n s t a t e of
a c t s a s a two
to the d e f i n i t i o n of
e l e c t r o n donor.
o x i d a t i o n s t a t e s to the m e t a l i s o f t e n o n l y
The
metal-
oxidation
assignment
of
f o r t h e p u r p o s e of " e l e c t r o n
counting".
The
a s s i g n m e n t of o x i d a t i o n s t a t e s to m e t a l s
complex, and
polynuclear,
f o r m i n g c l u s t e r s i s more
e s p e c i a l l y binuclear species are
common among the m e t a l c a r b o n y l s
and
carbonyl, M^CCO)^, exemplifies
the s i m p l e s t t y p e of compound, i n w h i c h
the two
h a l v e s of
i n o t h e r s , e.g.
Bidentate
19
and
bridges
Dimanganese d e c a -
the m o l e c u l e a r e j o i n e d o n l y by a m e t a l - m e t a l bond,
C o ( C 0 ) , bonding a l s o i n v o l v e s b r i d g i n g c a r b o n y l
o
Q
but
groups.
l i g a n d s , o f t e n found i n m o n o n u c l e a r c o m p l e x e s a s c h e l a t i n g l i g a n d s ,
can a l s o a c t a s b r i d g e s ,
W,
their derivatives.
particularly
e.g.
e t h y l e n e d i a m i n e ( e n ) i n M(CO)^en, M = C r ,
(CO) M(en) M(CO) , M = Cr,
and
3
3
20
3
Mo.
21
a m e t a l - m e t a l bond a r e r e q u i r e d
Mo,
I n some c a s e s , b o t h l i g a n d
to s a t i s f y
the i n e r t gas
rule.
22a
The
group of compounds [ F e C C O ^ S R ] , ,
c o u n t g i v e s a t o t a l o f o n l y 17
a r e d i a m a g n e t i c , but
e l e c t r o n s per
i r o n atom.
m e t a l - m e t a l bond to c o m p l e t e the e l e c t r o n s h e l l and
22b
The
an e l e c t r o n
postulated
a c c o u n t f o r the d i a -
magnetism, h a s been v e r i f i e d by X - r a y s t u d i e s .
In
the s i m p l e s t of m e t a l c a r b o n y l
l i g a n d i s n e u t r a l and
i n a zero o x i d a t i o n
d o n a t e s two
s t a t e , e.g.
complexes with n i t r o g e n l i g a n d s ,
the
e l e c t r o n s to the m e t a l , w h i c h i s f o r m a l l y
19
M(C0)^py
(M = C r , Mo, W, py = p y r i d i n e ) .
-4-
A few a n i o n i c o r g a n o n i t r o g e n
d e r i v a t i v e s a r e known, i n w h i c h t h e m e t a l i n a
+1 o x i d a t i o n s t a t e , a c c e p t s 2 e l e c t r o n s from t h e a n i o n i c l i g a n d , o r
alternatively,
t h e m e t a l i n a z e r o o x i d a t i o n s t a t e , a c c e p t s one e l e c t r o n from
23
the n e u t r a l l i g a n d , e.g. t h e compound shown i n F i g . I . l .
23
Dicarbonyl-jt-cyclopentadienyl-N-pyrrolyliron.
Fig.I.l
The
n i t r o g e n atom s t i l l
p o s s e s s e s a lone p a i r of e l e c t r o n s which
t h e o r e t i c a l l y donate to another
bridged
metal,
c o m p l e x e s h a v e been r e p o r t e d
thus
forming a bridged
dimer.
No
f o r p y r r o l e d e r i v a t i v e s , but a bridged
amino complex shown i n F i g . I . 2 h a s been d e s c r i b e d , i n w h i c h e a c h
d o n a t e s a t o t a l o f t h r e e e l e c t r o n s to the b o n d i n g .
the -RC=NR system
could
24a b
'
a p p e a r a b l e to complex t o m e t a l s
nitrogen
Donors c o n t a i n i n g
e i t h e r by d o n a t i o n
of
25
t h e l o n e p a i r , a s i n t h e complex shown i n F i g . 1 . 3
o r by u s e o f t h e it-bond,
2 *~
a s i n t h e compound shown i n F i g . I . 4 .
to t h o s e c o m p l e x e s c o n t a i n i n g u n u s u a l
P a r t i c u l a r r e f e r e n c e w i l l be made
types of c o - o r d i n a t i o n .
H
H
^<j
\
OCT
C
C0
^CO
C
0
0
, . ,
.
,
,.
\ 24a,b
Di-M-amino-bist t r i c a r b o n y l i r o n ; .
Fig.I.2
CH
Ph
CH
N
N
o
Ph
0
c
(Diacetylanil)irontricarbonyl
Fig.I.3.
.CH
25
CH
i
Ph—CH
/
Fe'
I \
c' I >:
o
c
o
0
(Cinnamaldehydeanil)irontricarbonyl
Fig.I.4.
2 5
-6-
C.
Bonding
The
b o n d i n g between a t r a n s i t i o n m e t a l
described q u a l i t a t i v e l y
c a r b o n y l group.
essentially
The
i n terms o f a-donor and
l o n e p a i r of e l e c t r o n s on
sp-hybrid o r b i t a l ,
with a vacant
and
and
a c a r b o n y l group c a n
i t - a c c e p t o r p r o p e r t i e s of
the carbon
forms a a - c o - o r d i n a t e bond by
atom, t h u s f o r m i n g
M-C
jr-bonds i n two
planes perpendicular
is
a s a w h o l e , and
expected
strengthens
to be g r e a t e r than one,
the M-C
bond.
w h i l e t h e C-0
energy.
of s u i t a b l e
non-bonding d - o r b i t a l s on
s y n e r g i c i n t e r a c t i o n p r o v i d e s a means o f a v o i d i n g c h a r g e
molecule
overlap
t r a n s i t i o n m e t a l h y b r i d o r b i t a l of s u i t a b l e symmetry and
energy which can o v e r l a p w i t h f i l l e d
the
atom i s i n an
I n a d d i t i o n , the c a r b o n y l group h a s i t - a n t i b o n d i n g o r b i t a l s
and
be
to e a c h
the
symmetry
metal
other.
A
s e p a r a t i o n i n the
T h u s , t h e M-C
bond o r d e r
bond
i s less
order
than
three.
Many of
c-donor and
the l i g a n d s found i n s u b s t i t u t e d m e t a l
it-acceptor p r o p e r t i e s .
empty d - o r b i t a l s w h i c h a r e a v a i l a b l e
l i g a n d s bonding v i a a f i r s t
and,
row
The
orbitals
heterocyclic
of the r i n g - s y s t e m ,
s t r e n g t h e n i n g of
The
systems
the M-L
and
h e a v i e r donor atoms i n a group
to a c c e p t e l e c t r o n s from the m e t a l
atom l a c k s u i t a b l e l o w - l y i n g empty
f u n c t i o n i n g only as a-donors they
Unsaturated
possess
but
orbitals
t h u s form l e s s r o b u s t compounds.
can a c t a s j t - a c c e p t o r s u s i n g the empty itthe s y n e r g i c i n t e r a c t i o n r e s u l t s
bond and more s t a b l e
in a
complexes.
e l e c t r o n d e n s i t y on t h e t r a n s i t i o n m e t a l s
can p a r t i c i p a t e i n t h i s
c a r b o n y l s p o s s e s s both
i s u s u a l l y such
type o f d o u b l e - b o n d i n g ; empty s , p and
that
they
d orbitals
are
-7-
available
to a c c e p t
partially
filled
is
and
o - d o n a t i o n , and
can
determined i n i t i a l l y
s e r i e s , and
by
i t s valence
bonds depends on
be
u s e d f o r it-back d o n a t i o n .
The
ability
density
the m e t a l to form s t r o n g i t -
requires
opposite e f f e c t s .
between a m e t a l and
six
electrons
The
o r b i t a l s o c c u p i e d by
Double bonding of
i n d - o r b i t a l s of
these
this
their
state.
the
example, i n an
s i x p a i r s of e l e c t r o n s
a
the c a r b o n y l s and
valence
a l s o h a v e an e f f e c t on
l i g a n d s . ^ F o r
complex, the m e t a l a c c e p t s
the c e n t r a l atom
formation of
the m e t a l i n a low
Symmetry c o n s i d e r a t i o n s
after
d e c r e a s e s i t s back-bonding a b i l i t y ;
t y p e a p p e a r s e s s e n t i a l f o r the
strength
o f it-bonds
octahedral
Cr°
t h r o u g h cr-bonds, and
has
s u i t a b l e symmetry a v a i l a b l e f o r b a c k b o n d i n g .
e l e c t r o n s a r e d i r e c t e d i n between t h e
towards u n o c c u p i e d l i g a n d o r b i t a l s o f
Thus, o c t a h e d r a l
of
t h u s a p o s i t i v e c h a r g e on
i t s a c c e p t o r a b i l i t y but
d e r i v a t i v e s , and
electron
the number of e l e c t r o n s i n non-honding d - o r b i t a l s
n e g a t i v e c h a r g e p r o d u c e s the
synergic
The
least
t h e p o s i t i o n of t h e m e t a l atom i n the t r a n s i t i o n
state.
a - e l e c t r o n a c c e p t a n c e and
increases
the non-bonding d o r b i t a l s a r e a t
symmetry f o r a Cr°
the c o r r e c t symmetry ( d or it
complex a l l o w s
ligands,
orbitals).
maximum b a c k b o n d i n g
to
occur.
The
ligands
i n any
one
b o n d i n g p o t e n t i a l i t i e s of
the bonding between one
ligands
bond, or
present.
the
complex a r e i n e f f e c t c o m p e t i n g f o r t h e
t h e c e n t r a l m e t a l atom, and
l i g a n d and
I n t h i s way,
stability
the
t h e m e t a l w i l l be
strength
so t h e e x a c t
influenced
by
of a p a r t i c u l a r m e t a l
of a complex, depends on
the
i n t e r a c t i o n of
limited
nature
the
of
other
ligand
the CT-
-8-
and it-bonding c a p a c i t i e s of a l l t h e l i g a n d s p r e s e n t , and
atom.
the m e t a l
l i g a n d s w i t h l e s s j t - a c c e p t o r c a p a b i l i t y , more b a c k d o n a t i o n
to the c a r b o n y l group o c c u r s and
w h i l e t h e C-0
capacity,
bond o r d e r d e c r e a s e s .
extremely
difficult.
s t a b l e combination
t o t h e i r a - and
there tends
of o t h e r l i g a n d s and
Spectra
Infrared
s p e c t r o s c o p y h a s p r o v e d one
c a r b o n y l s and
s t r e t c h i n g f r e q u e n c i e s of m e t a l
s t u d y of
be v e r y
The
1650
cm
back-bonding
o f CO
t o be
a
groups would
t h o s e of t h e
be
according
metal,
of the most u s e f u l t o o l s i n s t u d i e s
their derivatives.
The
carbonyl
c a r b o n y l compounds a r e found between about
^, a r e g i o n n o r m a l l y
f r e e of any
o t h e r a b s o r p t i o n s , and
the h i g h r e s o l u t i o n s p e c t r u m o f a compound i n t h i s a r e a c a n
a
often
informative.
symmetry p r o p e r t i e s of a c a r b o n y l complex d e t e r m i n e t h e number
t y p e o f i n f r a r e d a c t i v e v i b r a t i o n a l modes w h i c h a r e e x p e c t e d
g r o u p s , and
f o r the
t h e a r r a n g e m e n t o f t h e groups i n a complex c a n o f t e n be
from t h e a b s o r p t i o n p a t t e r n . ^
notably
the
particularly
carbonyl groups, balanced
it-bonding c a p a c i t i e s , and
of t r a n s i t i o n m e t a l
no
bond o r d e r would r e a c h
f u r t h e r displacement
For each metal
from
bond o r d e r i n c r e a s e s ,
I f t h e l i g a n d L had
Infrared
and
the M-C
then i n t h e complex Cr(CO).jL.j t h e C r - C
h y p o t h e t i c a l maximum of 2*0 and
2150
metal
F o r example, a s t h e c a r b o n y l groups i n C r ( C O ) ^ a r e p r o g r e s s i v e l y
r e p l a c e d by
D.
the c e n t r a l
The method h a s c e r t a i n
t h a t the l i g a n d s a r e u s u a l l y regarded
and
carbonyl
deduced
l i m i t a t i o n s however,
as p o i n t s when c o n s i d e r i n g
the
-9-
overall
symmetry o f t h e m o l e c u l e
observed,
caused
by t h e l o c a l
The
o f bands i s sometimes
symmetry o f t h e l i g a n d and l o w e r i n g o f t h e
symmetry t h r o u g h c r y s t a l p a c k i n g
bands i s a l s o
and s p l i t t i n g
i n the s o l i d .
A c c i d e n t a l coincidence of
observed.
CO s t r e t c h i n g
f r e q u e n c i e s a r e a r e f l e c t i o n o f t h e bonding
capabilities
of o t h e r l i g a n d s p r e s e n t i n a complex, s i n c e they depend upon t h e C-0 bond
order.
This reflects
ligands.
t h e M-C bond o r d e r w h i c h i s d e t e r m i n e d by t h e o t h e r
T h u s s t r o n g l y e l e c t r o n e g a t i v e groups s u c h a s h a l i d e i o n s o r p e r -
f l u o r o a l k y l and p e r f l u o r o a c y l groups i n d u c t i v e l y w i t h d r a w c h a r g e
metal,
reducing
i t s back-donating
bond o r d e r , r e f l e c t e d
from t h e
a b i l i t y and r e s u l t i n g i n an i n c r e a s e d C-0
i n t h e CO s t r e t c h i n g
f r e q u e n c i e s which a r e h i g h e r
than
28
in
the parent carbonyl
w i t h no n - a c c e p t o r
carbonyl
complexes.
Conversely,
p r o p e r t i e s donate charge
f r e q u e n c i e s w h i c h a r e much l o w e r
l i g a n d s such a s amines,
to the metal
resulting i n
than t h o s e o f t h e p a r e n t
carbonyl.
There
have been numerous c o m p a r i s o n s o f t h e r e l a t i v e cr-donor and it11 13
acceptor a b i l i t i e s of d i f f e r e n t l i g a n d s
' , using carbonyl frequencies
t h e m s e l v e s and t h e a p p l i c a t i o n o f s e m i - q u a l i t a t i v e f o r c e c o n s t a n t c a l c u l a t i o n s
11 13
has v e r i f i e d
The
t h e q u a l i t a t i v e c o n c l u s i o n s and y i e l d e d some new o n e s .
donor-acceptor
'
p r o p e r t i e s of l i g a n d s a r e not c o n s t a n t , but v a r y with the
n a t u r e o f t h e c e n t r a l atom and i t s e n v i r o n m e n t .
I n general,
unsaturated
n i t r o g e n - c o n t a i n i n g l i g a n d s a r e thought to p o s s e s s s m a l l a c c e p t o r
abilities;
p y r i d i n e , i n t h e d i s u b s t i t u t e d c o m p l e x e s [ M ( C O ) ^ ( p y > ] [M = C r , Mo,W] does
2
accept e l e c t r o n s , but in
t h e [M(CO),.py] c o m p l e x e s , t h e 5 c a r b o n y l
groups
-10-
accept
a l l the e l e c t r o n d e n s i t y and
comparison of
p y r i d i n e i s p u r e l y a donor.
the f o r c e c o n s t a n t - b o n d o r d e r
(dien = diethylene
t r i a m i n e ) and
r e l a t i o n s h i p for
A
(dienjMoCCO)^
( a c e t o n i t r i l e ^ M o ( C O ) ^ suggests
that
the
13
-C=N
bond h a s
a s m a l l , but
real ability
to a c c e p t
e l e c t r o n s from t h e
However, t h e r e i s some d i s c u s s i o n i n the l i t e r a t u r e a s to
reliability
abilities
of c a r b o n y l
of l i g a n d s .
frequency
29
s h i f t s a s a measure of the
Angelici
has
s t u d i e d the CO
He
assumed t h a t the aqueous pKa
r e l a t i v e measure o f
metal,
and
by
stretching frequencies
l i g a n d s ( p y r i d i n e and
rationalised
v a l u e s of the l i g a n d s a r e
it-bonding
l i g a n d s ( e . g . a m i n e s ) and
i n terms o f CT-bonding o n l y , and
i n terms of it-bonding
between m e t a l and
I n v i e w o f t h e l a r g e amount o f d a t a w h i c h s u g g e s t s
p y r i d i n e s do n-bond to the m e t a l ,
carbonyl
E.
a b i l i t y of l i g a n d s and
t h e CO
frequency
be
phosphine.
that phosphines
A n g e l i c i questions
the
and
the r e l a t i o n s h i p
f r e q u e n c i e s of t h e i r
metal
complexes.
Methods o f
Preparation
Most o f the o r g a n o n i t r o g e n t r a n s i t i o n m e t a l c a r b o n y l
prepared
a
c o u l d not
p y r i d i n e or
the
it-bonding
p h o s p h i n e s ) he c o n c l u d e d t h a t the c a r b o n y l
explained
between it-bonding
v a l u e s of
the a b i l i t y o f L to d o n a t e cr-bonding e l e c t r o n s to
comparing non
s h i f t s c o u l d be
the
it-bonding
of a number of s u b s t i t u t e d c o m p l e x e s , a s a f u n c t i o n o f the pKa
ligands.
metal.
by
one
of
three general
involves d i r e c t displacement
synthetic routes.
of CO
from t h e c a r b o n y l
The
by
c o m p l e x e s h a v e been
most common method
the l i g a n d , and
this
-11-
h a s been a c h i e v e d under a v a r i e t y of c o n d i t i o n s .
ammonia r e a c t
to g i v e [ N i ( C O ) N H ] and
3
p r o p o r t i o n a t e above -60°C ^ ,
Thus N i ( C O ) ^ and
liquid
[ N i ( C O > ( N H ) ^ , b o t h of w h i c h
3
2
dis-
3
w h e r e a s M(CO)g (M = C r , Mo)
reacts
with
bipyridyl
i n d i b u t y l e t h e r or l i g r o i n a t 130-150°C to p r o d u c e M ( C O ) ^ b i p y . ^
Refluxing
s o l v e n t s a r e o f t e n employed, b u t h e a t i n g o n l y
l i g a n d i n a s e a l e d tube or i n an a u t o c l a v e h a s
Photochemical
derivatives.
controlled
i n i t i a t i o n of r e a c t i o n s h a s p r o v e d a v e r s a t i l e r o u t e
T h i s method h a s
only with d i f f i c u l t y ,
the advantage t h a t the r e a c t i o n can
i f at a l l ,
example, W(CO)g u n d e r g o e s d i r e c t
o
stability
by
thermal
thermal
o f CO,
substitution reactions.
applicability
of t h e r m a l
of t h e s t a r t i n g m a t e r i a l s and
s u b s t i t u t i o n s o f t e n o c c u r a t much l o w e r
photochemically.
the f i n a l
products.
temperatures,
I f the metal
i n a s o l u t i o n of a weakly donating
metal
and
prepared
the
Photochemical
so
relatively
thermal r e a c t i o n s
carbonyl alone i s i r r a d i a t e d
s o l v e n t , s u c h a s THF,
then
the
resulting
c a r b o n y l - T H F complex c a n r e a c t w i t h a l i g a n d to p r o d u c e the r e q u i r e d
complex under e x c e e d i n g l y m i l d c o n d i t i o n s .
investigated
and
For
r e a c t i o n s i s l i m i t e d by
t h e r m a l l y u n s t a b l e s u b s t i t u t i o n c o m p l e x e s , i n a c c e s s i b l e by
c a n be p r e p a r e d
achieve
r e a c t i o n w i t h CH^CN to g i v e
c
The
to
be
w h i c h c a n be
b u t W(CO) (CH_CN) and W(CO).(CH_CN)_ have been
5 3
4 3 2
13
photochemically.
and
effected reaction.
to g i v e smooth, s t e p w i s e d i s p l a c e m e n t
W(C0)_(CH„CN)
3 3 3
the c a r b o n y l
these photochemical
S t r o h m e i e r and h i s group h a v e
reactions extensively,
a m e c h a n i s t i c p o i n t of v i e w , and
14
work i n t h i s f i e l d .
Strohmeier
from a p r e p a r a t i v e
has published a survey
of
-12-
Th e d i s p l a c e m e n t o f s u b s t i t u e n t g r o u p s from mixed c o m p l e x e s , b y t h e
d e s i r e d l i g a n d h a s proved
a w i d e l y a p p l i c a b l e method, and i s a g a i n
p a r t i c u l a r l y u s e f u l when d i r e c t d i s p l a c e m e n t o f CO from t h e c a r b o n y l
too d r a s t i c
direct
conditions.
displacement
requires
T h u s , f o r a c r y l o n i t r i l e w i t h t h e Group V I m e t a l s ,
o f CO was n o t f e a s i b l e , b u t t h e s e r i e s
(CH CHCN) M(CO),
0
Z
n
( n = 1, 2 o r 3, M = C r , Mo, W) were p r e p a r e d by l i g a n d d i s p l a c e m e n t
b-n
under
31
m i l d c o n d i t i o n s from t h e c o r r e s p o n d i n g a c e t o n i t r i l e c o m p l e x e s .
d i s p l a c e m e n t o f an a r o m a t i c , pseudo-aromatic
The
o r a c h e l a t i n g l i g a n d from a
complex o f t e n ( b u t n o t a l w a y s ) y i e l d s a s p e c i f i c
isomer, or a h i g h e r
s u b s t i t u t i o n p r o d u c t n o t o b t a i n a b l e through d i r e c t d i s p l a c e m e n t , e.g.
P i p e r a z i n e + Mo(CO)
> M o ( C O ) ( p i p ) + CO
only product
6
5
Piperazine + Mo(CO) (C H CH )
3
The
6
5
> (pip) Mo(CO)
3
3
3
+ CgHgCEj
3
2
a t t a c k on c a r b o n y l m e t a l l a t e i o n s by v a r i o u s donor groups i s a
method w h i c h h a s n o t been so w i d e l y u s e d , b u t h a s y i e l d e d s e v e r a l
most o f w h i c h
c a n be o b t a i n e d d i r e c t l y
though e.g.
20°
Na [W (CO)
2
The
2
1 ( )
] + NH
3
33
> 2W(CO) NH
three general p r e p a r a t i v e procedures
complexes c o n t a i n i n g n e u t r a l
required
+2^0
complexes,
5
3
+ 2NaOH + H
J
J
2
described y i e l d metal
ligands, but d i f f e r e n t
carbonyl
types o f r e a c t i o n s a r e
to i n t r o d u c e a n i o n i c l i g a n d s i n t o m e t a l c a r b o n y l s y s t e m s .
The most
common method o f p r e p a r i n g c o m p l e x e s c o n t a i n i n g a n i o n i c l i g a n d s i n v o l v e s
-13-
m e t a t h e t i c a l p r o c e s s e s o f the g e n e r a l
M-X
+ Y-Z
type
> M-Z
shown i n t h e
+
equation:
XY
I f M i s a m e t a l c a r b o n y l m o i e t y , t h e n X c a n be a h a l o g e n , i n w h i c h c a s e Y
would p r o b a b l y
a l k a l i metal,
be an a l k a l i m e t a l ,
or h y d r o g e n .
u s u a l l y sodium, and Y would be a h a l o g e n .
u s u a l l y o c c u r under m i l d c o n d i t i o n s and
product.
A l t e r n a t i v e l y , X c a n be
a l l o w ready
I n a d d i t i o n m e t a l c a r b o n y l h a l i d e s , and
a r e i n many c a s e s r e a d i l y a v a i l a b l e .
procedure i s given i n the
5
2
These r e a c t i o n s
i s o l a t i o n of
the d e s i r e d
sodium c a r b o n y l m e t a l l a t e s
example of t h i s
preparative
equation:
i t - C H F e ( C O ) I + C H NK
5
An
an
4
4
>
rt-C H Fe(CO) <r-NC H
5
5
2
4
4
+ KI
2
3
A n o t h e r p r e p a r a t i v e method i n v o l v e s r e a c t i o n of p o l y n u c l e a r m e t a l
c a r b o n y l s w i t h o r g a n o n i t r o g e n l i g a n d s , when, p a r t i c u l a r l y i n the c a s e o f
i r o n c a r b o n y l s F e ( C O ) g and F e . j ( C O ) ^ ,
2
carbonyl
2
t
n
e
r e s u l t i n g compounds c o n t a i n m e t a l
f r a g m e n t s l i n k e d by b r i d g i n g n i t r o g e n l i g a n d s .
r e a r r a n g e m e n t of
the l i g a n d o c c u r s , and
y i e l d i n g a compound c o n t a i n i n g two
Sometimes
i f the l i g a n d i s d i m e r i c i t can
bridging units.
t y p e s o f r e a c t i o n a r e d e s c r i b e d i n S e c t i o n H,
and
S e v e r a l examples o f
one
example i s g i v e n
equation:
H
CH=N-R +
2
36,182
Fe„(CO)
9
(C0„
R = P-CH C H
3
6
4
the
(CO)
split,
these
i n the
-14-
F.
R e a c t i o n Mechanisms
The
number o f s t u d i e s
o f r e a c t i o n mechanisms i s i n c r e a s i n g
rapidly,
34
and A n g e l i c i
The
has r e c e n t l y
p u b l i s h e d a c o m p r e h e n s i v e r e v i e w o f t h e work.
two most common ways o f s t u d y i n g t h e k i n e t i c s o f t h e r e a c t i o n s
use of i s o t o p i c l a b e l l i n g techniques
and
infrared
For
M(CO) ( A ) + L
x
y
( i i ) M(CO) ( A ) + L
x
y
A n g e l i c i noted
is
that
reactions:
> M(CO) , ( A ) L + CO
x-1
y
> M(CO) ( A ) .L + A
x
y-1
the v a s t m a j o r i t y proceed
according
to t h e r a t e l a w w h i c h
e i t h e r 1 s t o r d e r i n t h e complex and z e r o o r d e r i n t h e l i g a n d ,
o r d e r i n b o t h complex and l i g a n d .
terms i s o b s e r v e d
mechanisms
reactions)
spectroscopy.
t h e two t y p e s o f s u b s t i t u t i o n
(i)
or
( e s p e c i a l l y f o r CO exchange
are the
Often a r a t e law involving
but there i s k i n e t i c evidence
to support
or f i r s t
both these
rate
S i . l and S'"2
N .
N.
respectively.
34
In reactions
o f t y p e ( i ) i t h a s been found
that
i f A i s a ligand
c o n t a i n i n g n i t r o g e n o r oxygen a s t h e donor atom, o r i f A i s hydrogen o r a
halogen,
carbonyl.
then t h e c a r b o n y l groups a r e much more l a b i l e
than i n t h e p a r e n t
When A c o n t a i n s P, A s , Sb, S, Mn, Re, Au a s t h e donor atom, t h e
l a b i l i t y o f t h e c a r b o n y l groups i s l i t t l e
groups i n t h e p a r e n t c a r b o n y l .
d i f f e r e n t from t h a t o f t h e CO
The two t y p e s o f l i g a n d s
h a v e been c l a s s e d a s
3
" h a r d " and " s o f t " b a s e s , r e s p e c t i v e l y , a c c o r d i n g t o P e a r s o n ' s
classification
a p a r t from h y d r o g e n , w h i c h i s a " s o f t " b a s e b u t y e t h a s a p o w e r f u l
labilizing
-15-
e f f e c t on
t h e CO
groups.
h y d r i d e s r e a c t by
I t has
been s u g g e s t e d
34
that metal
a d i f f e r e n t mechanism from most o f
the
carbonyl
o t h e r M(CO) A
x y
complexes.
T h e r e has
so
f a r b e e n no
convincing e x p l a n a t i o n of
this
labilizing
34
effect.
jt-bonding arguments i n f a c t p r e d i c t
" h a r d " b a s e s h a v e no
the
c h a r g e on
n-bonding a b i l i t y and
the m e t a l c a u s i n g g r e a t e r
c a r b o n y l groups and
the r e v e r s e
would t h u s be
effect, since
e x p e c t e d to
bond, i n r e l a t i o n to the
I n f a c t jt-bonding arguments o n l y v e r y r a r e l y a c c o u n t f o r
34
r a t e s of s u b s t i t u t i o n i n the complexes.
34
ligands
r e s u l t s h a v e b e e n a c c o u n t e d f o r i n terms o f o-bonding
observed
; the
basic
d o n a t e c h a r g e t o the m e t a l v i a a o"-bond t h u s making i t a p o o r e r
c h a r g e a c c e p t o r from t h e
possible
that
the
c a r b o n y l groups.
s t a b i l i z a t i o n of
However, f o r S ^ l
the a c t i v a t e d
n i t r o g e n - l i g a n d s , f o r example, d e t e r m i n e s the
For
the
parent
carbonyls.
The
increase
b a c k d o n a t i o n from the m e t a l to
s t r e n g t h e n i n g t h e M-C
the
S^2 r e a c t i o n s , when A i s the c h e l a t i n g
34
d e r i v a t i v e s , i t has
b e e n shown
b a s i c i t y of
the
ligands
a greater
put
nucleophilic
ligand
attack.
that
increases.
c h a r g e on
complex by
reactions,
t h e more b a s i c
f a s t e r r a t e s o f CO
ligand
i t is
dissociation.
o - p h e n a n t h r o l i n e and
its
t h e r a t e of r e a c t i o n d e c r e a s e s a s
I t can
be
argued
the m e t a l and
S t e r i c considerations
that
the
t h e more b a s i c
r e d u c e i t s s u s c e p t i b i l i t y to
have a l s o been shown to be
of
34
importance
l o w e r the
: bulky ligands
r a t e of
A hinder nucleophilic
attack
a t the metal,
and
reaction.
Although these d i f f e r e n t l a b i l i z i n g
e f f e c t s of l i g a n d s i n c a r b o n y l
-16-
complexes a r e not understood,
they a r e u s e f u l
synthetically.
of r e a c t i o n mechanisms h a v e shown t h a t s e v e r a l
determining
observed
G.
f a c t o r s aire i m p o r t a n t
t h e k i n e t i c s and mechanisms of r e a c t i o n s .
e f f e c t s a r e not y e t f u l l y
C a r b o n y l Complexes i n O r g a n i c
The u s e o f t r a n s i t i o n m e t a l
and h e t e r o g e n e o u s
Thus,
studies
in
However, some o f
understood.
Syntheses
c a r b o n y l and
r e l a t e d c o m p l e x e s a s homogeneous
c a t a l y s t s i n c y c l i s a t i o n and p o l y m e r i s a t i o n r e a c t i o n s
o r g a n i c compounds h a s become w i d e s p r e a d . ^
The
polymerisation reactions
s t e r e o s p e c i f i c , v e r y s l i g h t c h a n g e s i n the m e t a l
c a t a l y s t causing d i f f e r e n t products
Of p a r t i c u l a r
of
r e a c t i o n s o f t e n o c c u r under
m i l d c o n d i t i o n s compared to u n c a t a l y s e d r e a c t i o n s and
are u s u a l l y extremely
the
to form.
i n t e r e s t h e r e a r e t h e r e a c t i o n s of u n s a t u r a t e d organo-
n i t r o g e n m o l e c u l e s c o n t a i n i n g c a r b o n - n i t r o g e n and/or n i t r o g e n - n i t r o g e n
m u l t i p l e bonds i n t h e p r e s e n c e of t r a n s i t i o n m e t a l
c a r b o n y l complexes.
A
36
r e v i e w of these r e a c t i o n s has r e c e n t l y appeared.
S c h i f f b a s e s , a z o compounds
oximes, phenylhydrazones, semicarbazones, a z i n e s , u n s a t u r a t e d i m i d e s ,
and n i t r i l e s
a l l r e a c t w i t h c a r b o n monoxide i n t h e p r e s e n c e of a m e t a l
carbonyl c a t a l y s t , u s u a l l y a t f a i r l y high temperature
c y c l i s a t i o n products.
all
amides
and p r e s s u r e to
yield
S c h i f f bases y i e l d only substituted phthalimidines
other r e a c t i o n s lead
to a m i x t u r e
D i c o b a l t o c t a c a r b o n y l i s by
but
of p r o d u c t s .
f a r the most commonly u s e d c a t a l y s t
i n these
36
reactions.
Other metal
and R h ( C O ) „ but
9
c a r b o n y l s have been t r i e d ,
i n g e n e r a l they a r e l e s s e f f i c i e n t
s u c h a s Fe(CO),., N i ( C O ) ^
than C o _ ( C O )
R
or
exhibit
-17-
no
and
catalytic
elucidate
activity
the mechanism of
compounds w i t h CO.
R
1
and
at a l l .
The
Some s t u d i e s h a v e been u n d e r t a k e n
the c a t a l y s e d c y c l i s a t i o n o f
36
these
to
try
unsaturated
r e a c t i o n r a t e s of a s e r i e s of a n i l s i n w h i c h R, t h e n
R" v a r i e d , were o b s e r v e d , and
i t was
c o n c l u d e d t h a t the m e t a l
carbonyl
R'
o -6
/ \ L / >
R"
became a t t a c h e d
to the
l o n e p a i r of e l e c t r o n s
t h a n t h e i t - e l e c t r o n s of t h e
i m i n o group.
The
on
the n i t r o g e n
atom, r a t h e r
r i n g c l o s u r e of b e n z o n i t r i l e w i t h
36
c a r b o n monoxide i n t h e p r e s e n c e o f h y d r o g e n and
d e u t e r i u m was
and
true c a t a l y s t i n r i n g
the r e s u l t s s u p p o r t the h y p o t h e s i s t h a t
r e a c t i o n s of n i t r o g e n
the
compounds i s c o b a l t h y d r o c a r b o n y l and
also studied
not
closure
dicobalt
octacarbonyl.
36
A l t h o u g h R o s e n t h a l and
Wender
had
insufficient
experimental
to s u p p o r t a r i g o r o u s
mechanism o f r i n g c l o s u r e ,
s e q u e n c e of s t e p s
the c y c l i s a t i o n of a r o m a t i c a l d e h y d e and
for
phenylhydrazones ( r i n g c l o s u r e
b a s e s and
azo
compounds):
of
these
they s u g g e s t e d a
probably p a r a l l e l s
,
evidence
possible
ketone
that of S c h i f f
-18-
R
a
HCo(CO)
N
NHPh
HR
N-NHPh
Co(CO)
R = H, C H . P h
CO
a
HR
HR
^N-CONHPh
\
<
IT
HR
\
-NHPh <
N-NHPh
CO
H
ACO(CO)
2H
OQ
N-Ph
4H
a
N
N—Ph
0
+
NH
3
R e c e n t l y , a number o f c o m p l e x e s o f some o f t h e s e u n s a t u r a t e d
compounds w i t h i r o n c a r b o n y l s h a v e been i s o l a t e d ,
r e f e r e n c e s 3 6 , 2 4 b ) and t h e i r
i n t e r e s t i n g i n themselves,
structures
nitrogen
( s e e , f o r example
elucidated.
These complexes a r e
but they could w e l l prove u s e f u l i n attempts to
-19-
e l u c i d a t e t h e mechanisms of t h e c a t a l y s e d
complexes
w i l l be d i s c u s s e d l a t e r
cyclisation reactions.
The
i n this chapter.
Amongst o t h e r m e t a l c a r b o n y l c a t a l y s e d
o r g a n i c s y n t h e s e s , the r e a c t i o n
of
36
amines w i t h m e t a l c a r b o n y l s to y i e l d
C o b a l t , ruthenium
formamides and u r e a s , i s o f
interest.
and manganese c a r b o n y l s h a v e b e e n u s e d i n t h e s e r e a c t i o n s ,
w h i c h a r e n o r m a l l y c a r r i e d out a t h i g h t e m p e r a t u r e s and p r e s s u r e s .
been l e a r n t m e c h a n i s t i c a l l y about
these r e a c t i o n s
from a s t u d y o f
Much h a s
low
36
t e m p e r a t u r e , s t o i c h i o m e t r i c r e a c t i o n s between amines and m e t a l c a r b o n y l s .
The r e a c t i o n o f h y d r a z i n e w i t h c a r b o n monoxide i n t h e p r e s e n c e o f
c o b a l t , or n i c k e l c a r b o n y l s a t e l e v a t e d
t e m p e r a t u r e s and p r e s s u r e s y i e l d s
s e m i c a r b a z i d e and h y d r a z o d i c a r b o n a m i d e , and
36
s t u d i e d a t low t e m p e r a t u r e s .
H.
iron,
t h e s e r e a c t i o n s have a l s o been
S u r v e y o f Compounds
1. T i t a n i u m and
Vanadium
The p a r a m a g n e t i c h e x a c a r b o n y l v a n a d i u m i s t h e o n l y u n s u b s t i t u t e d Group V
c a r b o n y l known.
B e i n g one
e l e c t r o n s h o r t o f t h e k r y p t o n c o n f i g u r a t i o n , V(CO)g
r e a d i l y d i s p r o p o r t i o n a t e s i n the p r e s e n c e of N-bases,
r e a c t i o n of V(CO>
6
w i t h l i q u i d ammonia a t -30°
_ I
[ V ^ C C O ) , ] „ and N H . [ V ( C 0 ) , ] ,
b Z
*\
b
the CO
produced
y i e l d i n g V(CO)g
t o 20°C y i e l d s
[V
I I
.
Thus
(NH ) ]
3
6
being p a r t i a l l y evolved as a
37
gas and p a r t i a l l y u s e d
to form u r e a .
Mono- and p o l y d e n t a t e a r o m a t i c amines
e.g. a n i l i n e , N , N ' - d i p h e n y l e t h y l e n e d i a m i n e and o- and
react
similarly,
i n benzene,
a t room t e m p e r a t u r e .
p-phenylenediamine
B e n z o n i t r i l e and a c e t o -
-20-
n i t r i l e react analogously
c a t i o n s e.g.
b u t a - and y - p i c o l i n g i v e t e t r a c o - o r d i n a t e
[ V C a - N C ^ C ^ )^] [ V ( C 0 ) ] .
6
HV(C0)
2
6
and
aqueous ammonia gave
38
eventually
NH [V(C0) ].
4
6
R e a c t i o n between d e r i v a t i v e s of V ( C 0 ) g and
n i t r o g e n l i g a n d s has
not
39
y i e l d e d any mixed c a r b o n y l b a s e c o m p l e x e s .
(diphenylphosphine)ethane
( D P ) a t 120°
V(C0)^ r e a c t s with
to y i e l d V ( C 0 ) D P
1,2-bis-
and V ( C O ) ( D P )
4
2
2
,
and w i t h 1 , 1 , l - t r i s ( d i p h e n y l p h o s p h i n e m e t h y l e n e ) e t h a n e ( T P ) to y i e l d
39
V(C0).jTP
, but
r e a c t i o n of t h e s e d e r i v a t i v e s w i t h b i p y , o-phen, and
1
(2,2 ,2"-tripyridyl) results
and
a l l t h e CO
tripy
i n e l i m i n a t i o n of b o t h the phosphorus l i g a n d s
g r o u p s , g i v i n g V ° ( b i p y ) " ^ , V ° ( o - p h e n ) " ^ and
3
Cyclopentadienylvanadium
3
t e t r a c a r b o n y l and
d i c a r b o n y l r e a c t w i t h b i p y , o-phen and
3
V°(tripy),,. ^
cyclopentadienyltitanium
t r i p y w i t h l o s s of
cyclopentadiene
41
and
c a r b o n y l g r o u p s , y i e l d i n g M ( b i p y ) ^ , M(o-phen)^ and M ( t r i p y ) ^ (M =
2. Chromium, Molybdenum and
Tungsten
As T a b l e 1.1 shows, t h e m a j o r i t y of Group V I m e t a l
d e r i v a t i v e s are simple s u b s t i t u t i o n products
a l i p h a t i c and
aromatic
above h a v e been u s e d
and
amines.
carbonyl
nitrogen
of the hexacarbonyls
with
A l l t h r e e methods of p r e p a r a t i o n m e n t i o n e d
to o b t a i n t h e s e d e r i v a t i v e s , i n w h i c h one,
o c c a s s i o n a l l y f o u r CO
V,Ti).
two,
g r o u p s have been d i s p l a c e d from t h e p a r e n t
three
carbonyl.
Some r e p r e s e n t a t i v e e x a m p l e s of t h e p r e p a r a t i v e methods a r e g i v e n i n t h e
(i)
a ) C r ( C 0 ) + l i q . NH^
C r ( C O ) N H + CO
equations:
120°
42
80°
M(C0) + liq.NH »
M ( C O ) ( N H ) + 3C0
(M = C r , Mo,
W).
6
6
v
3
5
3
3
3
3
-21-
T a b l e 1.1.
Group V I M e t a l C a r b o n y l Complexes
Monodentate
(i)
Ligand
ligands
Metal
M(CO) L
Cr
Mo
W
42,45,47,52
33,46,48,52
33,52,54
C H N
3 5
Cr
19,65
44,64,65
(py)
Mo
19,45,47,55,
56,57,59
19,46,48,50,
57,62,63,76
19,33,49,54,
57,76
19,33,46,48
50,57,63
19,33,57
65,93
31,61,77
31,61,77,80
31,61,77,80
NH_
C
C
W
5
cis-M(C0) L
4
_
_
-
CHgCN
Cr
Mo
W
31,61,79,80
31,62,80
31,61,78,80
81
31,61,80
31,61,78,80
31,61,78,80
81
CH =CHCN
Cr
Mo
W
31,94
31
31,82,83,94
31
31
31
Cr
Mo
W
46,19,61
19,46,61,62
19,49,53,61
Cr
Mo
W
45,55,56,57
Cr
Mo
W
55
-
58
33
Cr
Mo
W
52,60
52,60,62
52,54.60
60
60
60
Mo
46
2
(cyclohexylamine)
C H NH
6
5
2
p-NH C H NH
2
C H
5
1()
6
4
2
NH
(piperidine)
-
49,51,53,57
2
2
2
cis-M(C0) L
3
20,42,44
21,33,42
42,43
66,93
31
31,83
_
_
-
50
-
_
_
-
50
-
_
-
_
-
(pip)
HN(CH CH ) NH
2
-
32
(piperazine)
2
6 4
(4-aminopyridine)
Mo
58
58
-22-
Metal
Ligand
C
H
N
5 6 2
(2-methylpiperazine)
C HgNH
4
(pyrrolidine)
0(CH CH ) NH
2
2
2
(morpholine)
o-NH C H NH
2
6
4
2
Et N
3
M(CO) L
c
Cr
Mo
3
2
5
3
Cr
Mo
W
52
52,32
52,32
32
32
Cr
Mo
W
32
32
32,49,53,54
32
32
Cr
55
Cr
Mo
W
52,60
52
Cr
67
(2,6-lutidine)
4-C1C..H.N
5 4
Cr
67
C H N
Cr
Mo
67
30,67
Cr
67
a-picoline
Cr
67
urotropin
Mo
30
isotropin
Cr
67
PhCN
Cr
79
g
?
quinoline
(quin)
C H N
9
?
cis-M(CO).,L
'3 3
30
30
52,60
(CH ) C H N
cis-M(CO),L_
4 2
(isoquinoline)
(hexamethylenetetramine)
32
-23-
Ligand
Metal
M(CO) L
Ligand
CH NH
Cr
Mo
W
45,85
86
54,85
PhNHNH
C„H,NH
2 o I
Cr
Mo
W
45,52,85
52,85
52,85
NH NH
Mo
46
ethylenediamine
(en)
Mo
46
HC(CH CH ) N
W
3
2
9
5
Me NH
2
n _ C
2
2
2
2
3
2
H
N H
6 13
2
n-C H NH
5
n
2
49,53
Me.N
J
4-BrC,H, NH„
6 4 2
W
49,51,53
4-CH_0C,H. NH3
6 4 2
W
49,51,53
4-CH,C,H.NH
3 6 4 2
W
4-BrC H,N
5 4
W
0
c
51
Bidentate
/
(CH ) CHNH
3
c
(ii)
4-CH-C H N
3 5 4
2
2
Metal
M(C0) L
Mo
46
Cr
Mo
W
52,85
52,85
49,52,53
54,85
Cr
Mo
W
52
52
52
Cr
Mo
W
52
52
52
Cr
Mo
W
52
52
52,53,54
W
49,53
W
49,53
5
49,53
ligands
Ligand
Metal
M(CO) L
Ligand
Metal
M(C0) L
8-aminoquinoline
Cr
30
1,2-diamino-2methylpropane
Cr
95
(C H N) CH
Mo
30
(C H
Mo
30
Mo
30
Cr
Mo
W
89
89
89
4
8
2
2
4
5
Cyclohexane-1,2diamine
N.N N'.N'-tetrame t h y l e n e e t h y l e n e diamine
;
Cr
55
88
N) CH
2
(Et N) CH
2
Cr
1 ( )
2
2
2
1-propylenediamine
4
-24-
Ligand
Metal
Phenanthroline
(o-phen)
Bipyridyl
(Bipy)
M(CO) L
M(CO) L
Cr
Mo
W
44,45,65,71,84,89
65,84,89
66,84,89
72
71
71
Cr
19,30,45,70,73,74,
76,84,89
19,30,68,73,75,76,
84,89
19,33,66,73,76,84,
89
72
Mo
W
H NC„H NH
(e thylenediamine)
(en)
trimethylenediamine
(iii)
Tridentate
Cr
Mo
W
Cr
Mo
W
4
19,45,47,61,89
19,46,61,89
19,61,89
89
89
89
ligands
Ligand
Metal
M(C0) L
diethylenetriamine
(dien)
Cr
Mo
W
19,61,68,69,87
19,21,61,68,86
19,61,68
2,2',2"-tripyridyl
Mo
W
108
108
Cr
30
3
CH -N-RCH -N-RCH-NR
2
2
R = CH
_
_
n
3
n
n
°2 5
2
71
71
2
-25-
(iv)
Polynuclear d e r i v a t i v e s containing n i t r o g e n bridges
Compound
Ref.
m-Phenylenediamine [ C r ( C O ) ^ ]
2
55
p-Phenylenediamine [ C r ( C O ) ]
2
48,55,59
p-Phenylenediamine [ M o ( C O ) l
2
59
5
5
1,3,5-Triaminobenzene [Cr(CO),.]
Piperazine
[Mo(CO) ]
Piperazine
[W(CO) l
5
5
(CO) Cr(en) Cr(CO)
3
(CO) Mo(en) Mo(CO)
3
3
3
(v)
3
3
3
55
32
2
32
2
20
21,50
Mixed D e r i v a t i v e s
M(C0) XY
3
X
Y
M
Ref.
bipy
NH
3
Cr,Mo,W
42
o-phen
NH
3
Cr,Mo,W
42
bipy
py
Mo
o-phen
py
o-phen
P(0Et)
bipy
3
PPh
J
bipy
SPh
bipy
P(0Et)
o-phen
2
PPh
5
bipy
SO,
o-phen
S0
(py)
S0
2
93
Mo,W
93
Mo
91
W
2
2
3
90,91,93
Ref.
91
91,93
93
Mo
90,91
Mo
91
Mo
W
Mo
W
2
90,91,93
W
Mo
M(CO) XY
91,93
93
93
93
Mo.W
93
Mo,W
93
91
91,93
93
2
-26-
(vi)
H e p t a - c o - o r d i n a t e and r e l a t e d d e r i v a t i v e s
Ref.
Compound
73,98
[Mo(bipy)(CO) Br ]
3
2
[W(bipy)(CO) Br ]
2
73
[W(bipy)(CO) I ]
73
3
3
2
[W(bipy)(CO) (HgCl) ]
73
Mo(py) (CO) Cl
98
2
2
3
2
2
Mo(bipy)(CO) Cl
3
98
2
Mo(o-phen)(C0) Br
2
Mo(o-phen)(CO) Cl
2
3
3
[Mo(CO) (bipy) I]I
2
2
98
98
99
3
[Mo(CO) (o-phen) I]I
2
2
3
99
[Mo(bipy) (CO) I]I
99
[W(o-phenl|:C0) I]I
99
[Mo(bipy)(CO) I ]
73
2
2
2
3
2
2
[Mo(o-phen) (CO) I]I
2
(vii)
2
99
jt-arene d e r i v a t i v e s
(Mesi t y l e n e ) G r ( C O ) < q u i n )
122
(Mesitylene)Cr(CO) (py)
121,122
(tere)Cr(CO) (NCPh)
120,122
(tere)Cr(CO) (NCMe)
120
(tere)Cr(CO) (quin)
120
(tere)Cr(CO) (aniline)
120
2
2
?
2
2
2
-27-
Compound
Ref.
(tere)Cr(CO) (py)
121,122
(tere)Cr(CO) (pip)
121,122
(Benzene)Cr(CO) py
121,122
(Benzene)Cr(CO) (quin)
122
[(CH ) C ]Cr(CO) (quin)
122
2
2
2
2
3
6
6
2
(Benzene)Cr(CO) (CH =CH-CN)
94
(Me s i ty1ene)Cr(CO > (CH =CH-CN)
94
(tere)Cr(CO) (CH =CH-CN)
94
2
2
2
2
2
2
[ t e r e = t e r e p h t h a l i c a c i d d i m e t h y l e s t e r (CH^C0 ) C^H^].
2
(viii)
C y c l o p e n t a d i e n y l and R e l a t e d
jtCpMo(CO) (PhN=N-)
Derivatives
102,103
2
jtCpMo(C0) (p-CH C H N=tO
102
jrCpMo ( CO ) ( p-CH OC H N=N^
101,102
«CpMo(CO) (p-N0 -C H N=N-)
102
jtC pMo ( CO ) ( an t h r a q u i none - N=N-)
102
irCpW(CO) (PhN=N-)
103
2
3
2
6
4
3
2
6
2
6
4
4
2
2
[ i t C p M ( N H ) ( C O ) ] r e i n e c k a t e " (Mo and W)
+
3
3
+
[ ifCpM(NH ) (CO ) ] B P h "
106
(Moand W)
106
[ jrCpM(N H )(C0 > ] r e i n e c k a t e ( M o and W)
106
3
3
4
+
2
4
3
+
[itCpM(N H )(C0) ] BPh "
2
4
3
4
+
t«CpM(CO) (bipy)] PF "
2
6
+
[itCpM(CO) (o-phen)] PF "
2
6
+
[jtCpM(CO) (CH CN) ] PF "
2
3
2
6
(Mo and W)
106
(Mo and W)
107
(Mo and W)
107
(Mo and W)
107
2
-28-
Compound
Ref.
+
[ JtCpMo(CO ) ( C H C N ) ( P P h ) ] P F "
107
irCpMo(CO) (COCH C H N)
105
2
3
3
2
(ix)
2
5
6
4
T h i o c y a n a t e and r e l a t e d d e r i v a t i v e s
Compound
Metal
Cr
Mo
W
+
<CH ) N [M(CO) NCS]"
3
4
5
+
[AsPh ] [W(CO) NCO]"
4
2 +
[Ni(phen) ] [Cr(CO) NCO] "
5
45
2
* [(CO) Cr-NCS-Cr(CO) ]
5
111,119
5
2+
[Ni(phen) ] [(CO) Cr-NCS-Cr(CO) ]
3
5
5
-
112,119
+
[N(CH ) ] [(CO) Cr-NC-Cr(CO) ]
3
K
4
109,111,119
109
109
110
5
3
Ref.
5
112,119
5
Cr(CO) NCS
113,119
5
+
[Et N] [Cr(CO) NC(CN) ]"
4
5
114
2
+
[AsPh ] [Mo(CO) NC(CN) ]"
2
114
[Et N] [W(CO) NC(CN) ]~
114
4
5
+
4
5
2
[M(CO)„NCH]
Cr,W
115
Cr,Mo,W
116
Cr,W
117
Cr.W
117
Cr,W
117
D
[(CO) M-NCCN-M(CO) ]
5
5
+
(Ph P) N [M(CO) NCS]
3
2
_
5
+
(Ph,P) N [(CO),M-SCN-M(CO) ]"
0
c
J
- i t -
J
+
(Ph P) N [fcO) M-CN-M(CO) ]~
3
2
5
itCpMo(CO) NCS
x
paramagnetic
5
118
-29-
b)
(
U
— Twn-,
T^VX
Nfi^F^
or i . H . r .
Cr(CO), + quinoline
o
)
(MeO-C H Cr(CO)
6
(iii)
5
6 6
1 1 5
+ py
3
Na [Cr(CO) ] + aq.o-C H (NH )
2
B i - and
5
6
4
2
"
1 2
Cr(CO),(quin) +
J
° ° > Cr(CO) py
3
6
CO
4
3
5
» Cr(CO) [o-C H (NH > ]
2
5
6
4
2
5
2
p o l y - d e n t a t e l i g a n d s have a l s o y i e l d e d many d e r i v a t i v e s .
monodentate N-donors do n o t r e p l a c e more t h a n 3 CO
groups from the
h e x a c a r b o n y l , o - p h e n a n t h r o l i n e and b i p y r i d y l , u n d e r d r a s t i c
Whereas
parent
conditions give
71 72
M(CO) (p-phen)
2
5
or M ( C O ) ( b i p y ) .
2
2
potential chelating ligands prefer
monodentate l i g a n d s .
I t i s interesting
2
2
2
2
32
W ,
5
b u t a l s o C r ( C O ) g ( o - or p - C g H ( N H ) ) .
4
2
tetramine) has 4 p o t e n t i a l
30
2
(M = C r , ^ Mo ^"'"^).
donor s i t e s ,
metal
Presumably s t e r i c
through
d o u b l e bond.
4 6
2
4
2
2
chelate
on
Urotropin(hexamethylene-
i n determining
ligand.
the l i g a n d may
bond t o t h e
the n i t r o g e n , o r from t h e
In addition, acrylonitrile
the o l e f i n i c
2
p-CgH (NH ) )Cr(CO)^,
e f f e c t s are important
c o m p l e x e s o f the Gp.VI m e t a l s
v i a a cr-bond from t h e l o n e p a i r
m u l t i p l e bond.
2
b u t a c t s a s a monodentate l i g a n d i n
the t y p e s o f d e r i v a t i v e s formed w i t h e a c h
I n the n i t r i l e
5
) , but 3 m o l e c u l e s b r i d g e i n t h e
2
3
Mo(CO) (HN(CH CH ) NH).
Ethylenediamine a c t s as a
2
4
3
2
( C O ) ^ C r ( o - or
i n M ( C 0 ) e n c o m p l e x e s (M = C r , Mo,
complexes ( C O ) M ( e n ) M ( C O )
2
but a l s o
S i m i l a r l y m- and p - p h e n y l e n e d i a m i n e y i e l d
Mo(CO),_(urotropin).
some
Thus p i p e r a z i n e ( H N ( C H C H ) N H ) y i e l d s
2
3
that
to form b r i d g e d compounds, o r t o a c t a s
[ ( C O ) M H N ( C H C H ) N H M ( C O ) J , M = Mo,
5
to n o t e
CN
(CH =CHCN) c a n form a n-complex
2
I n f r a r e d and n.m.r. s p e c t r o s c o p i c
5 5
-30-
t e c h n i q u e s have been used t o show t h a t bonding i s through t h e n i t r o g e n l o n e
pair i n a l l
t h e complexes shown i n T a b l e I . l . ( i ) except M(CO) (CH =CHCN)
3
2
3
31
31 83
(M = Mo,
W, ' ) when jt-bonding from t h e o l e f i n i c double bond occurs.
Mixed complexes o f t h e t y p e MCCOX^XY (where X = o-phen o r b i p y , Y =
a monodentate l i g a n d ) a r e r e a d i l y p r e p a r e d by d i r e c t displacement o f one
CO g r o u p , and i n some cases d i s p l a c e m e n t o f a 2nd CO has been achieved t o
g i v e MCCO^XY^ complexes.
Some o f t h e complexes a r e l i s t e d i n T a b l e I . l . ( v ) .
92
In
a d d i t i o n , Houk and Dobson
have prepared complexes w i t h Y = py, PPh ,
3
P ( 0 E t ) , (C H ^NH , CH CN, ( C g H ^ ^ P , ( n - C ^ ^ P , Pt^As,
3
6
1
2
3
(i-C^O^P,
( n - C H 0 ) P , ( C H 0 ) P , (CjH 0) HOP, Pb^Sb, P ^ B i , Pt^Se, DMF, CI^CONH^
92
4
9
3
3
3
5
2
CH CSNH , ( N H ) C S , (PhO^P, and s t u d i e d t h e i r i . r . s p e c t r a .
3
2
2
2
Angelici
95
and Graham
have s t u d i e d t h e r a t e o f r e a c t i o n o f Cr(C0)^(X-o-phen) w i t h
P ( 0 C H ) C C H ( L ) t o g i v e Cr(CO> L(X-o-phen), where X = 5 , 6 - d i c h l o r o - , 5 - n i t r o 2
3
3
3
4 , 7 - d i p h e n y l - , 3-methyl-, 3 , 5 , 7 - t r i m e t h y l - , 3 , 4 , 7 , 8 - t e t r a m e t h y l - and
95
96
3,4,6,7-tetramethyl-.
The analogous Mo(C0)^(X-o-phen)
and W(C0)^(X-o96
phen)
also react w i t h various ligands (L = P(OC H )
PPh , P ( 0 P h )
96
2
P ( n - C H ) , P(OCH ) CCH
4
all
9
3
2
3
3
5
3 >
3
and P 0 C H ) , t o g i v e M ( C 0 ) L (X-o-phen).
3
6
g
3
3 >
For
the Cr(CO) (X-o-phen) complexes, t h e r e a c t i o n s were found t o proceed
4
a c c o r d i n g t o a f i r s t o r d e r r a t e l a w , and were independent o f t h e
95
c o n c e n t r a t i o n o f L.
But the r e a c t i o n r a t e increases w i t h increasing
b a s i c i t y o f X-o-phen, c o n t r a r y t o jr-bonding arguments, and i t i s suggested
t h a t t h e more b a s i c c h e l a t e s s t a b i l i z e t h e t r a n s i t i o n s t a t e t o a g r e a t e r
e x t e n t than weaker bases.
observed.^
F o r t h e Mo and W complexes a two-term r a t e law i s
-31-
The s e v e n - c o - o r d i n a t e complexes l i s t e d i n Table I . l . ( v i ) a r e a l l d i a m a g n e t i c , u n s t a b l e complexes.
They have been prepared e i t h e r by the
o x i d a t i o n o f M(CO) (bipy) or M ( C 0 ) ( o - p h e n ) w i t h h a l o g e n ,
4
4
73 99
'
or by the
a d d i t i o n o f py, o-phen, or b i p y t o a s o l u t i o n o f t h e dihalogeno-compounds
98
[M(CO)^^]2'
^
n
a d d i t i o n , s t a b l e n o n i o n i c h e p t a c o - o r d i n a t e compounds o f
the t y p e b i p y C c O ^ X M M ' X ^
00
(where M = Mo, W, and M'X = G e C l , GeBr ,
3
3
3
G e l , S n C l , S n B r , S n l , SnCl CH , S n C l ^ H g , S n C l C H , S n C l C H ,
3
3
3
3
2
3
2
2
3
2
SnCKCgH,.^, GeCljCgH^), have been prepared by an " o x i d a t i v e
6
5
elimination"
r e a c t i o n o f t h e type:
X
(CO) M + XY
n
>
(CO)
M
n-1 \
n
v
between M(CO) bipy and compounds o f t h e type M'X^.
4
A few analogous compounds
w i t h o-phen^"^ i n s t e a d o f b i p y have a l s o been prepared.
The i . r . and n.m.r.
data on these complexes suggest t h a t they e x i s t i n 2 i s o m e r i c forms i n
solution.
S e v e r a l arene m e t a l c a r b o n y l d e r i v a t i v e s o f t h e type (X-CgH^CrCcO^I'
are l i s t e d i n Table I . l . ( v i i ) .
Complexes w i t h s u b s t i t u e n t s
i n the benzene
r i n g have been prepared t o s t u d y the e f f e c t o f X groups on the s t a b i l i t y o f
94 120 121
the complexes.
'
'
122
'
E l e c t r o n - w i t h d r a w i n g groups reduce the charge
on t h e m e t a l and encourage L — * Cr d o n a t i o n , b u t e l e c t r o n r e l e a s i n g
f a v o u r Cr —*• L back bonding.
As expected from these arguments,
groups
terephthalic
a c i d forms more s t a b l e mixed complexes w i t h poor j t - a c c e p t o r l i g a n d s t h a n
120
94
does m e s i t y l e n e .
I n the complexes w i t h L = Ct^CH-CsN , the type o f
-32-
bonding between a c r y l o n i t r i l e and t h e m e t a l was o f p a r t i c u l a r i n t e r e s t .
I.R.
and n.m.r. t e c h n i q u e s showed t h a t t h e compounds a l l c o n t a i n e d CTN } M bonds,
except f o r (CH )g(^Cr(CO ) (CH =CHCN), which c o n t a i n e d a j t - o l e f i n i c - m e t a l bond.
3
2
2
T h i s can be r e a d i l y u n d e r s t o o d , s i n c e t h e s i x m e t h y l groups i n t h e benzene
r i n g w i l l donate charge t o t h e m e t a l , thus d i s c o u r a g i n g d o n a t i o n o f t h e
nitrogen
lone p a i r s t o the metal.
Of t h e j t - c y c l o p e n t a d i e n y l d e r i v a t i v e s l i s t e d i n Table I . l . ( v i i i ) ,
o f t h e t y p e irCpM(CO) (RN -) a r e o f s p e c i a l i n t e r e s t .
2
They a r e prepared by
2
+
the r e a c t i o n o f NafjtCpMoCCO)^] w i t h t h e diazonium s a l t s R N B F
2
+
RN PF ~
2
6
1 0 2
those
or
4
, o r i n t h e case o f (itCpM(CO) PhN ^, by t h e r e a c t i o n o f
2
jtCpM(CO).jH w i t h p h e n y l h y d r a z i n e . T h e
w i t h the N 0
+
2
ligand
RN
+
2
i s formerly
l i g a n d i n t h e same way t h a t RNC i s r e l a t e d t o CO.
isoelectronic
The
complexes a r e somewhat a i r - s e n s i t i v e , b u t a r e n o n - i o n i c and d i a m a g n e t i c ,
h a v i n g t h e expected n.m.r. spectrum.
Thus, i n these c o v a l e n t a r y l a z o
d e r i v a t i v e s t h e n e u t r a l RNg-group must be d o n a t i n g 3 e l e c t r o n s t o the m e t a l ,
so t h a t i t has t h e i n e r t gas c o n f i g u r a t i o n ( c . f . NO i n n i t r o s y l
complexes).
The t h i o c y a n a t e and r e l a t e d compounds shown i n Table I . l . ( i x ) form an
i n t e r e s t i n g c l a s s o f compounds, as t h e p o s s i b i l i t y o f l i n k a g e isomerism
exists.
I.R. s t u d i e s o f these complexes have been i n t e r p r e t e d as showing t h e
109-119
types o f bonding i n d i c a t e d i n t h e t a b l e .
+
complexes a r e s t a b l e , b u t Me N [Mo(C0),.NCS] ~
4
111,113,119
compounds a r e u n s t a b l e .
'
'
fc
The a n i o n i c Cr and W
and t h e n e u t r a l
paramagnetic
..
..
.
,
. ., .
The b m u c l e a r anions have no b r i d g i n g
c a r b o n y l groups and t h e two m e t a l atoms a r e j o i n e d by a l i n e a r -NCS-^H-2,117,119
-33-
-NC-,
(SCN)
1 1 2
2
'
1 1 7,
L
1
9
o r -NCCN-
1
1
6
bridge.
y i e l d s b o t h jT-CpMo(CO) SCN a n d
3
chromatography.
The S-bonded i s o m e r ,
R e a c t i o n between jt-CpMo(CO> H and
3
rt-CpMo(CO) NCS,
i n a c e t o n i t r i l e or chloroform
s o l u t i o n a t 35°C i s o m e r i s e s t o t h e N-bonded i s o m e r .
(SCN) , only
t h e S-bonded i s o m e r
was
f o r t h i s compound.
2
observed
s e p a r a b l e by column
3
was o b t a i n e d
With n-CpW(CO) H and
3
and no i s o m e r i s m
A f e w m i s c e l l a n e o u s compounds n o t l i s t e d
i nsolution
i n t h e t a b l e s n e e d t o be
123
mentioned.
Bock and D i e c k
have p r e p a r e d
an i n t e r e s t i n g
s e r i e s of metal
carbonyl d e r i v a t i v e s with non-aromatic nitrogen-it systems.
dialkyl
c y a n a m i d e s R N-CN w i t h C r and Mo h e x a c a r b o n y l s
yielded
i n hydrocarbon s o l v e n t s
2
g i v e s mono-, d i - and t r i - s u b s t i t u t e d
(R N-CN)M(CO)
2
(R2JV-CN) M(C0)
2
4
derivatives.
and ( R N - C N ) M ( C O )
2
5
2
and ( R N - C N ) M ( C O ) .
2
GC
3
4
Reaction of
I r r a d i a t i o n a t 20-30°C
w h e r e a s h e a t i n g a t 50-60°C gave
The l i g a n d s u s e d were
3
[^^NCN
^ e
/
NCN ,
0
C
\
NCN
6
H
H \
,
^NCN .
V__/
C ^
6 11
^
I . R . s t u d i e s i n d i c a t e d t h a t t h e m e t a l - l i g a n d bonding i s v i a t h e lone p a i r o f
e l e c t r o n s on t h e t e r m i n a l n i t r o g e n , and t h a t t h e l i g a n d s h a v e l i t t l e
jt-
123
acceptor
ability.
R e a c t i o n o f e.g. c i s - { j i s ( c y a n o - p i p e r i d i n e ) - m o l y b d e n u m
t e t r a c a r b o n y l with other
l i g a n d s such a s d i a c e t y l h y d r a z o n e ,
o s p h i n i m i d e s and 1 , 4 - d i a z a b u t a d i e n e gave
/ CH -C=N-NH \
"
V/
\CHV-C=N-NH
3
2
Mo(C0) ,
4
:
(Ph,P=NH) Mo(C0),
9
l
and
NH
CH--C-NC^
I
>o(C0).
CH.-C-N^
NH
2
2
5
triphenylph-
0
respectively.
1 2 3
-34-
I n t h e r e a c t i o n between Mo(CO)g and d i a l l y l - c y a n a m i d e
f CH =CH-CH >^
\124
^^N-CN J
, 4 moles o f CO are evolved per mole o f Mo(CO), and
^ CH =CH-CH *
'
2
2
2
2
a d i m e r i c complex i s formed, which from i . r . and n.m.r.
e v i d e n c e , i s assigned
spectroscopic
t h e s t r u c t u r e shown i n F i g . I . 5 .
C_H
N
CN
HC
N
CO
CO
CO
I
II
CO
N
CN
N
R
Mo
R
C_H
CH
CH
R = CH
3
Fig.1.5.
The analogous compound was prepared
(R = C H ) .
from m e t h y l - a l l y l - c y a n a m i d e
1 2 4
3
The non-bonding o r b i t a l s o f c i s - a n t i - 1 , 4 - d i a z a - l , 3 - b u t a d i e n e s a r e i n
p o s i t i o n s which a r e g e o m e t r i c a l l y f a v o u r a b l e f o r f o r m a t i o n o f b i d e n t a t e donor
bonds.
125 126
'
I n a d d i t i o n , t h e l o w e s t unoccupied it* o r b i t a l has s u i t a b l e
-35-
symmetry and energy f o r jt-back d o n a t i o n , from m e t a l d - o r b i t a l s .
molybdenum
Several
t e t r a c a r b o n y l d e r i v a t i v e s have been prepared by a v a r i e t y o f
r o u t e s , i n c l u d i n g d i r e c t r e a c t i o n , displacement ( a s above) and " c o n d e n s a t i o n "
j
i.e.
+ 2RNH, +
Mo(CO),
>
"""T^^
^Mo(CO),
R
[For R
1
aryl].
= C H ; R = OH.
6
5
For R
1
= CH ; R = OH, 0CH , NH
3
3
2>
N(CH )
3
2 >
alkyl,
The complexes a r e a i r s t a b l e and i n r e a c t i o n w i t h o t h e r l i g a n d s e.g.
PPh , and I ,
3
2
CO i s d i s p l a c e d and t h e d i a z a b u t a d i e n e l i g a n d i s r e t a i n e d .
125
Analogous chromium and t u n g s t e n d e r i v a t i v e s have been prepared by i r r a d i a t i o n .
The i . r . , n.m.r. and e l e c t r o n i c s p e c t r a o f t h e molybdenum
studied
complexes have been
i n d e t a i l , and the bonding i s d e s c r i b e d i n a q u a l i t a t i v e
M.O.
scheme as a c-bond between t h e N-lone p a i r and the m e t a l , b u t i n a d d i t i o n
t h e r e i s b a c k - d o n a t i o n from t h e f i l l e d m e t a l d - o r b i t a l s i n t o i r - a n t i b o n d i n g
126
o r b i t a l s on t h e l i g a n d .
127
T r i p h e n y l p h o s p h i n i m i d e r e a c t s w i t h M(CO)^ (M = Mo, V?)
t o give either
(Ph P=NH) Mo(CO)
3
2
4
o r a t a h i g h e r temperature [ ( P h P = N H ) M o ( C O ) l
compound h a v i n g b r i d g i n g c a r b o n y l groups.
3
2
3
2
the l a t t e r
S p e c t r o s c o p i c techniques a r e
a g a i n used t o show t h a t oN — - } M bonding o c c u r s , b u t a l s o t h a t added
127
s t a b i l i t y o f t h e complexes comes from d e l o c a l i s a t i o n o f the charge:
-36-
H
—P=N-
->
— P - "N.
5M
R e a c t i o n between methylmethoxycarbene-pentacarbonylchromium and h y d r o x y l amine ( d r y ) proceeds as shown i n t h e e q u a t i o n :
^>OCH
H
3
(CO) Cr—
+
5
^CH
128 129
'
a b s
H NOH
2
-
e t h e r
>
OCH
3
N
/
=
=
C
(CO) Cr
3
CH
5
(CO) Cr
/
5
+
0
C
H
^CH
3
3
^ N = C ^
H
\
+
H 0
2
3
The two i s o m e r i c forms o f t h e ( m e t h y l a c e t i m i d a t o ) pentacarbonylchromium
were separated by f r a c t i o n a l c r y s t a l l i s a t i o n and were shown by v a r i a b l e
temperature
n.m.r. t o be i n t e r c o n v e r t i b l e .
Reaction
o f t h e carbene w i t h
u n s y m m e t r i c a l l y s u b s t i t u t e d h y d r a z i n e s , f o r example N,N-dimethyl
g i v e s known n i t r i l e chromium p e n t a c a r b o n y l
hydrazine
d e r i v a t i v e s , perhaps by t h e
.
.
.
128,129
mechanism shown:
'
^OCH
(CO) Cr^C^
5
\
GII_
3
3
c
+H N-N(CH_)„
" 2 " ' 3'2
0
[
\?*-*^h
• (CO) Cr^C^
+ CH^OH
5
\
3
i CI1
I
""3
s
y
c
X
1
(CO) CrNCCH + H N ( C H )
5
3
3
2
-37-
A pseudo a l l y l i c s t r u c t u r e has been proposed f o r the complex
130
jr-CpMo(CO) (Ph CNCPh )
, prepared by r e a c t i o n o f ic-CpMo(C0) Cl w i t h 2 moles
130
2
2
2
3
of Ph C=NLi, i n which t h e l i g a n d must a c t as a 3 e l e c t r o n donor.
2
K i n g a n d B i s n e t t e ^ " * have prepared a n o v e l molybdenum compound by r e a c t i o n
of [jr-CpMo(C0) ]
3
heterocyclic
2
with 2-chloromethylpyridine.
The p r o d u c t c o n t a i n s a
r i n g w i t h t h e m e t a l atom as p a r t o f t h e r i n g , as shown i n F i g .
1.6.
CO —
Mo —
CO
N ^ C I L , — C=0
Fig.I.6,
The analogous W compound c o u l d n o t be prepared.
105
The compound N - n - b u t y l t h i o p i c o l i n a m i d e ( b t p ) r e a c t s w i t h
n-CH
Fig.I.7.
[Mo(C0) X l
4
2
2
-38-
(X = C I , B r ) t o g i v e M o C c O ^ b t p ^
behave as u n i - n e g a t i v e
bidentate
( F i g . I . 7).
Thiopicolinamides usually
l i g a n d s by l o s s o f a p r o t o n , b u t i n these
complexes, t h e l i g a n d appears t o be a c t i n g as a monodentate n e u t r a l l i g a n d ,
131
co-ordinating
t o t h e m e t a l v i a t h e p y r i d i n e N-atom.
(C H )Ti(NMe ) M(CO)
5
5
2
3
3
(M = Cr, Mo, W )
1 3 2
The
are reported
compounds
t o form when
rt-CpTi(NMe„)_ and M(CO), a r e i r r a d i a t e d i n cyclohexane s o l u t i o n .
15
b
s p e c t r a s u p p o r t t h e assignment o f NMe b r i d g e s ,
2
The i . r .
b u t the n.m.r. s p e c t r a
132
cannot be i n t e r p r e t e d on t h i s
3a.
basis.
Manganese
In contrast
t o the Gp.VI m e t a l c a r b o n y l s , dimanganese decacarbonyl
disproportionates
w i t h most n i t r o g e n bases w i t h l i t t l e o r no n-acceptor
p r o p e r t i e s , e.g. M n ( C O )
2
1
+ piperidine
1 0
2
0
) [Mn
+ I I
( p i p ) ] [Mn'^CO),.] •
6
1 3 3 , 1 3
2
^
However, some s t r o n g bases e.g. p y r i d i n e , a n i l i n e and o-phenylenediamine
134
g i v e m o n o s u b s t i t u t e d d e r i v a t i v e s Mn(CO) L.
4
n-Butylamine seems
unique
i n t h a t i t r e a c t s a t room temperature t o g i v e
+ I
_ I
1 3
[ M n ( C O ) ( n - C H N H ) ] [ M n ( C O ) ] . ^ W i t h bases h a v i n g i t - a c c e p t o r p r o p e r t i e s ,
Jo
- f s o l133,134,137
, ^ . .
by
i n n o n - up no sl ya mr m esto rl iv•ec natlnsl.y s Iu rbu rs at di•it au t ei doJ n dimers
u t i o n s o f these
e.g.r e ba ic pt iy o, n o-phen,
a r e o dimers
btained
5
4
g
2
5
paramagr
y i e l d s paramagnetic monomers
133,134
dimers:
Mn„(CO) + bipy
^
-"-w
133
, which r e a d i l y combine t o g i v e
n o
1n
[bipyMn(CO) ] + Mn (CO)
3
2
2
1 Q
<
o l a r
"-P
,
solvent
symmetrical
[bipyCcO.Mh-MnCCO),.]
Jj
3
(bipy)Mn(CO)
3
+ Mn(CO)
5
-39-
I n p o l a r s o l v e n t s , b i p y and o-phen cause d i s p r o p o r t i o n a t i o n ' ' " " ^ ' t o g i v e ,
f o r example [ M n ^ ^ C o - p h e n ^ ] [Mn'^CcO)^] .
The
c a r b o n y l h a l i d e d e r i v a t i v e s i n Table I . 2 ( i i ) are i n almost a l l
cases prepared by the a c t i o n o f the l i g a n d on Mn(CO)^X o r [MnCcO^X^Monodentate, and most b i d e n t a t e amines r e p l a c e
carbonyl
two CO groups t o g i v e
s p e c i e s , b u t some o f the p y r i d i n e - 2 - a l d i m i n e s
complexes.
give bridged
tribinuclear
M n ( C O ) ( d i e n ) l was prepared from [ ( m e s i t y l e n e ) M n ( C O ) . j ] l .
3
Mn(CO),_X complexes r e a c t i n a s l i g h t l y d i f f e r e n t manner w i t h l i q u i d ammonia
or e t h y l e n e d i a m i n e , t o g i v e i o n i c compounds.
135 138
'
The k i n e t i c s o f t h e
141
r e a c t i o n s between Mn(CO),-X compounds and l i g a n d s have been s t u d i e d .
For a l l n i t r o g e n l i g a n d s s t u d i e d , the r e a c t i o n s proceed d i r e c t l y t o the c i s d i s u b s t i t u t e d complexes, a t a r a t e which i s independent o f the l i g a n d
concentration.
The r a t e s o f r e a c t i o n decrease i n the o r d e r C l . ^ B r > I .
d i s s o c i a t i v e (SN^) mechanism accounts f o r the e x p e r i m e n t a l
Reaction of methylprimary
observations.''"^
o r phenyl-manganese p e n t a c a r b o n y l s [RMn(CO)^] w i t h
o r secondary amines l e a d s t o a c y l d e r i v a t i v e s o f t h e
142
MnCCO^CcORXNHR'R" ).
A
type
K i n e t i c s t u d i e s on the r e a c t i o n o f MeMn(CO),. w i t h
c y c l o h e x y l a m i n e and N-methylcyclohexylamine i n v a r i o u s s o l v e n t s s u p p o r t a
mechanism o f s o l v e n t a s s i s t e d m i g r a t i o n , p r o b a b l y
143
than a c a r b o n y l
techniques.
group.
Kraihanzel
o f the m e t h y l group, r a t h e r
Through the use o f i . r . and n.m.r. s p e c t r a l
and Maples''"^ s t u d i e d the r e a c t i o n s o f MeMn(CO), w i t h
a l k y l a m i n e s and a n i l i n e t o g i v e o n l y c i s - a c e t y l d e r i v a t i v e s .
r e a c t i o n s do n o t go t o c o m p l e t i o n
These
and the p r o d u c t s are u n s t a b l e
i n solution.
-40-
T a b l e 1.2.
Manganese Carbonyl Complexes
(i)
Derivatives o f Mn (C0) .
o
lr
Type o f Compound
L or L
Mn(C0) L
4
[L Mn(CO) -Mn(CO) ]
2
3
5
tMn(CO) L ]
3
2
2
+ I
_ I
[Mn (C0) L][Mn (C0) ]
5
5
Mn(C0) L
3
2
Mn (C0) L
2
9
[Mn^CO^L^V
-
(X
2
Ref.
o-phenylenediamine
134
aniline
134
pyridine
134
bipy
134
o-phen
133,134,13 7
bipy
134
o-phen
134
n-butylamine
134
o-phen
133
NH
3
133
NH
3
135
- I
= M n ( C 0 ) ; BPh )
5
+
[Mn(C0) L ] X
4
2
4
2 _
2
o-phen
136
o-phen
13 7
o-phen
137
2
(X - = [ Z n C l D
2
[Mn(C0) L ]X
4
(X
-
_
2
= Co(C0) )
4
(C0) CoMn(C0)„L
4
(ii)
(a)
6
9
D e r i v a t i v e s o f manganese c a r b o n y l h a l i d e s
Mn(C0) L X
3
2
Ref.
X
I
NH (C H )
142
CI
aniline
145
2
6
1 1
-41-
X
L
Ref •
Br
aniline
29,138,141
Cl
pyridine
138,141
Br
pyridine
29,138,141
I
pyridine
138,139,141
NO.j
pyridine
140
Br
o-C1C H NH
Br
p-CH OC H NH
Br
(CH ) CHNH
Br
3-BrC H.N
5 4
4-CH_C-H,N
3 5 4
p-CH_C,H.NH
3 6 4 2
o-CH,C,H.NH.
3 6 4 2
6
3
3
4
6
29,141
2
4
2
29
2
29
2
29
c
Br
29
1
Br
141
0
Br
141
C'l
NH
3
11
Br
NH
3
11
I
Mn(C0) L'X
NH
11
3
3
X
1/
Ref.
Cl
(C H N-CH=N-CH )
138
Cl
(C H.N-CH=N-C,H )
5 4
65
138
Cl
o-phen
Br
o-phen
I
o-phen
Cl
bipy
138
Br
blpy
138
I
bipy
N0
I
5
4
C
3
3
C
133,138
138
133,138
138,139
bipy
140
diethylenetriamine(dien)
154
-42-
(c)
[Mn(CO) X] L"
3
2
X
(d)
L"
CI
(C H N-CH=N-N=CH-NC H )
Gl
(C H N-CH=N-(CH ) -N=CH-NC H )
138
CI
(C H N-CH=N-C H -N=CH-NC H )
138
Ionic
5
4
5
5
4
5
2
4
6
4
2
5
5
4
4
Ref.
[Mn(CO) (NH ) ]Br
135,138
[Mn(CO) (NH ) ]Cl
135
[Mn(C0) (en)]Br
138
4
3
3
3
2
3
4
[Mn(CO) (bipy)(py)]N0
3
[Mn(CO) (bipy)P0 ]N0
3
3
140
3
140
3
[Mn(CO) (bipy)(P0 ) ]N0
2
3
2
3
-
140
Na[Mn(CO) (NH C H )]
142
[Mn(CO) (NH Me)]Cl
145
4
5
2
6
11
2
[Mn(CO) (NH Me)]PF
5
2
145
6
[Mn(CO) (NH Et)]Cl
5
145
2
[Mn(CO) (NH Et)]PF
5
(a)
138
4
derivatives
Compound
(iii)
Ref.
2
145
6
Organo-manganese d e r i v a t i v e s
Mn(CO).
—
— — 4 (CORXNHR'R")
R
NHR'R"
Me
C H NH
6
11
Ref.
142,143,144
2
Me
NH_
Me
NH(CH )(C H )
Me
Ph
Ph
Me
142
3
N H
C
H
2 6 5
NH C H
2
N H
C
6
H
6
142,143,144
n
1
1;L
2 6 5
quinoline
4
2
142
1
4
2
194
-43-
(b)
Mn(CO) (CONHR)(NH R)
/|
2
R
Ref.
Me
145
Et
145
CH(CH )
3
145
2
i t - c y c l o p e n t a d i e n y l and r e l a t e d compounds
it-CpMn(C0) L
o
L
Ref.
Aniline
146
Piperidine
146,150,151
Benzonitrile
147
Acetonitrile
147,150
Pyridine
148,150,152
Piperazine
149,150
Triethylenediamine
149
Urotropin
149,150
NH
150,151
3
NMe
150,151
n-Propylamine
150,151
n-Hexylamine
150,151
Me NH
150,151,152
Pyrolidine
150,151
2,5-Dimethylpyrolidine
150
V-Picolin
150
Ethylamine
151
3
2
-44-
(b)
(v)
[rt-CpMn(CO)J L
(c)
2
( i t - C H ^ H ^ )Mn(CO) L
2
L
Ref.
L
Ref•
Piperazine
149
Pyridine
148
Triethylenediamine
149
Piperidine
153
T h i o c y a n a t e and r e l a t e d d e r i v a t i v e s
(a)
Mn(CO) L NCS
3
2
L
Ref.
(CO)
156
Pyridine
155,156,157
(p-CH C H NH )
157
(4-CH C H N)
155,157
p-ClC H NH )
157
(p-FC H NH )
157
PPh
155,157
3
3
6
6
5
4
6
4
4
2
4
2
2
3
AsPh
157
3
SbPh„
(b)
157
Mn(CO) L'NCS
3
hL
Ref.
bipy
155,157
1,2-bis(diphenylphosphino)ethane
157
-45-
B o t h i n d u c t i v e and s t e r i c e f f e c t s o f t h e group bonded t o n i t r o g e n a r e
i n f l u e n t i a l i n determining the p o s i t i o n of e q u i l i b r i u m .
A methyl-migration
mechanism i s a g a i n supported.'''^
The
by
carbonamido c a r b o n y l complexes Mn(CO)^(CONHR)(NH R) a r e prepared
2
t h e a c t i o n o f a l a r g e excess o f an amine (MeNH , EtNH
2
on Mn(CO)^Br.
2
o r (CH^^CHNH,,)
An X-ray a n a l y s i s has v e r i f i e d t h e s t r u c t u r e shown i n
Fig.I.8.
NH CH
2
3
Fig.I.8.
The
complexes decompose i n s o l u t i o n t o g i v e Mn (CO)^Q and t h e N - a l k y l f o r m a m i d e
2
+
R e a c t i o n w i t h HC1 y i e l d s RNH Cl and [Mn(CO),-NH R]CI, i s o l a t e d as t h e PFg"
3
salt.
2
The c a r b o n y l a t e c a t i o n r e a c t s w i t h more amine t o form t h e
carbonamido complex again:
CH C1
2
+
[ M n ( C O ) N H R l C l " + 2RNH5
2
2
» MnfCOV (CONHR)(NH R) + RN&j CI
2
-
Strohmeier and h i s co-workers^*' '''"'^ have prepared s e v e r a l
d i e n y l manganese d i c a r b o n y l
jt-cyclopenta-
d e r i v a t i v e s by u.v. i r r a d i a t i o n o f a s o l u t i o n o f
-46-
it-CpMn(CO)
3
and t h e l i g a n d .
R e l a t i v e l y weak bases gave i s o l a b l e
products,
b u t s t r o n g e r bases e.g. Et^N gave u n s t a b l e d e r i v a t i v e s which c o u l d n o t be
. .
_ 146-151
isolated.
The t h i o c y a n a t e manganese c a r b o n y l d e r i v a t i v e s a r e o f i n t e r e s t because
of
t h e ambident n a t u r e o f t h e l i g a n d .
S o l i d Mn(CO),.(CNS) i t s e l f c o n t a i n s a
Mn-S bond^*' ( i n c o n t r a s t t o t h e Gp.VI m e t a l c a r b o n y l d e r i v a t i v e s ^ ^ ) .
s p e c t r a o f t h e compound i n s o l v e n t s such as CHCl^, 0^^012,
I.R.
CHC^ and e t h y l
a c e t a t e a r e c o n s i s t e n t w i t h an e q u i l i b r i u m between Mn-S and Mn-N bonded
isomers.
I n CH^CN, however, t h e i . r . i n d i c a t e s t h a t t h e compound e x i s t s
s o l e l y as t h e N-bonded isomer, b u t on e v a p o r a t i o n o f t h e s o l v e n t , t h e Sbonded isomer i s r e c o v e r e d . S u b s t i t u t i o n by N - l i g a n d s leads i n a l l cases
t o cis-Mr^CO^I^NCS complexes where t h e t h i o c y a n a t e group i s bonded t o t h e
m e t a l v i a t h e n i t r o g e n atom.
Other l i g a n d s , such as PPh^, AsPh^ and SbPh^
g i v e S-bonded t e t r a c a r b o n y l d e r i v a t i v e s e.g. Mn(C0) (PPh )SCN, S-bonded
4
3
c i s - t r i c a r b o n y l d e r i v a t i v e s ( f o r AsPh^ and SbPh^) and N-bonded t r a n s t r i c a r b o n y l d e r i v a t i v e s e.g. trans-[Mn(C0).j(SbPh.j)2NCS] .
Several o f these
compounds can be prepared b o t h by d i r e c t r e a c t i o n o f Mn(C0),.(CNS) w i t h t h e
l i g a n d , and by metatheses i n v o l v i n g t h e c o r r e s p o n d i n g
complex and potassium t h i o c y a n a t e .
I t i s thought
c h l o r o - o r bromo
t h a t t h e e x t e n t o f M-CO
jT-bonding i n a t h i o c y a n a t e c a r b o n y l complex may p l a y an i m p o r t a n t r o l e i n
s t a b i l i z i n g a g i v e n mode o f m e t a l - t h i o c y a n a t e attachment.
When jr-bonding i s
r e l a t i v e l y weak, as i n Mn(C0),.(CNS), t h e more p o l a r i s a b l e s u l p h u r end i s
p r e f e r r e d by t h e m e t a l .
The s u l p h u r bonding i n c r e a s e s n e g a t i v e charge on t h e
-47-
m e t a l and enhances M-CO ir-bonding.
On s u b s t i t u t i o n by l i g a n d s w i t h l e s s rt-
bonding a b i l i t y than t h e CO groups, e.g. amines, t h e n e g a t i v e charge on t h e
metal increases,
thus i n c r e a s i n g t h e M-CO jr-bonding, and t h e m e t a l p r e f e r s
the n i t r o g e n r a t h e r than the sulphur atom.
Thus t h e e x t e n t o f M-CO rt-
bonding c o n t r o l s t h e p o l a r i s a b i l i t y o f the m e t a l , and a t some unknown,
c r i t i c a l stage, changes t h e p r e f e r e n c e
the t h i o c y a n a t e
s t a b i l i z i n g Mn-S
AsPh„ and SbPh.
t o the other.
o f t h e l a t t e r f o r one donor atom o f
S t e r i c f a c t o r s may a l s o p l a y a r o l e i n
l i n k a g e i n the c i s - t r i c a r b o n y l s c o n t a i n i n g the b u l k y
ligands
157
Two compounds o f i n t e r e s t n o t i n c l u d e d i n t h e T a b l e s , have been
prepared by r e a c t i o n o f NaMn(CO),. w i t h 2-chlorofi}ethyldimethylamine and w i t h
2o- c v,i
h l o r o m e -u
t h yil p y r-ai d m e : 36,105
0
0
I
OC
(i)
NaMn(C0) + ClCH CH N(CH )
5
2
2
3
THF
CH
Mn
2
OC
CH
0
CH,r
3
\'CH.
3
0
IIC
0
OC
(ii)
THF
NaMn(CO),. +
N
CH„C1
CH
Mn
OC
c
\
6
5^
-48-
The
s t r u c t u r e s o f t h e complexes were deduced m a i n l y from i . r . e v i d e n c e , and
are
analogous t o t h e Mo compound mentioned e a r l i e r . P r e s u m a b l y the f i r s t
s t e p i n the r e a c t i o n i s s i m p l e halogen d i s p l a c e m e n t t o g i v e
e.g.
(CH^ ^NCCl^^MnCCO),. which can then undergo i n t r a m o l e c u l a r rearrangement
the
n i t r o g e n l o n e p a i r a t t a c k i n g the m e t a l , and a c a r b o n y l group
between the m e t a l and t h e a l k y l group, t o g i v e t h e c y c l i c
with
inserting
acylheterocycle.'"^
T h i s i s a s i m i l a r pathway t o t h a t envisaged f o r the p r e p a r a t i o n o f
Mn(CO) (COR)(NHR'R") c o m p o u n d s .
1 4 2
4
3b.
Rhenium and
'
1 4 3 , 1 4 4
Technetium
The few r e p o r t e d d e r i v a t i v e s o f rhenium c a r b o n y l , c o n t a i n i n g N - l i g a n d s ,
seem t o i n d i c a t e t h a t t h e Mn and Re c a r b o n y l systems behave f a i r l y
similarly.
There i s o n l y one r e p o r t e d d e r i v a t i v e o f t e c h n e t i u m c a r b o n y l c o n t a i n i n g a
n i t r o g e n l i g a n d , presumably because o f the u n a v a i l a b i l i t y o f the c a r b o n y l .
The f i r s t d e r i v a t i v e s o f rhenium c a r b o n y l i t s e l f were R e ( C O ) p y
3
Re(C0),jO-phen, which were r e p o r t e d i n 1941, and were t h o u g h t t o be
2
and
1
dimers. ^
162
The carbomethoxycarbonyl compound
was p r e p a r e d by the a c t i o n o f MeO
on
+
[ R e ( C O ) ( o - p h e n ) ] , (see Table 1 . 3 ( D ) :
[ R e ( C O ) ( o - p h e n ) ] Z n C l * ( C H ) C O + K OMe~
4
+
4
+
2
2
2
3
2
M e 0 H
>
Re(CO) (o-phen)C0 CH
3
2
3
The a c t i o n o f HCl on t h i s complex r e v e r s e s t h e r e a c t i o n and t h e c a t i o n i s
o b t a i n e d as
+
[Re(CO) o-phen] Cl*HCl.
Mononuclear
4
and b i n u c l e a r rhenium c a r b o n y l h a l i d e s r e a c t r e a d i l y w i t h
donors t o g i v e u s u a l l y , d i s u b s t i t u t e d rhenium t r i c a r b o n y l h a l i d e d e r i v a t i v e s .
-49-
The
d i m e r i c h a l i d e s o f t e n r e a c t under m i l d e r c o n d i t i o n s than the monomers.
For example, p y r i d i n e r e a c t s w i t h Re(CO)^I d u r i n g 5 hours r e f l u x t o g i v e
139
py Re(CO) I
2
, whereas t h e dimer [ R e ( C O ) ^ I ]
3
2
w i t h p y r i d i n e g i v e s t h e same
1
139
p r o d u c t a f t e r •§• hour.
However, l i q u i d NH^ r e a c t s w i t h Re(CO),.Cl t o g i v e
Re(CO)^(NH )Cl and [ R e ( C O ) ^ ( N H ) ^ ] C l , t h e l a t t e r b e i n g i s o l a t e d as t h e
158
3
3
tetraphenylborate s a l t .
has been i d e n t i f i e d
l i q u i d NH .
No CO i s evolved
d u r i n g t h e r e a c t i o n ; formamide
i n t h e p r o d u c t s , so t h e d i s p l a c e d CO must r e a c t w i t h
R e a c t i o n o f (o-phen) w i t h [ R e ( C 0 ) ^ ( N H ) C l ] d i s p l a c e s NH and
3
3
CO t o g i v e Re(C0) (o-phen)C1.
158
3
3
[ R e ( C 0 ) ^ ( N H ) ] C l r e a c t s w i t h excess p y r i d i n e
3
2
to g i v e R e ( C O ) p y C l .
3
2
I n d i r e c t s y n t h e t i c methods have a l s o been used.
[ReCCOXjEPhgX] ,
2
3
where E = S i , X C l o r E = Se, X = B r , r e a c t w i t h donors e.g. p y r r o l i d i n e t o
g i v e Re(CO) (HNC^H ) X , (X = C l , B r ) compounds.
3
g
2
But [ R e ( C O ) S e P h I ]
3
2
2
reacts
w i t h p y r r o l i d i n e t o g i v e t h e i o n i c complex [Re(CO)_(HNC.H_)„]I, i s o l a t e d as
J
H
O
J
the t e t r a p h e n y l b o r a t e s a l t . ^ ^
K i n e t i c s t u d i e s o f t h e r e a c t i o n o f t h e t e t r a c a r b o n y l h a l i d e dimers o f
rhenium w i t h t h e l i g a n d s p y r i d i n e , y - p i c o l i n and a - c h l o r o p y r i d i n e have been
164
reported.
For t h e f i r s t
two l i g a n d s , m o n o s u b s t i t u t e d complexes o f t h e
type Re(CO)^LX (X = C l , B r , I ) were c h a r a c t e r i s e d .
The r e a c t i o n s a r e f i r s t
o r d e r i n b o t h m e t a l c a r b o n y l and l i g a n d , and f o r t h e same reagent t h e r a t e s
decrease w i t h changes i n the halogen C l > Br y I . This can be e x p l a i n e d on
the b a s i s o f d i f f e r e n t e l e c t r o n e g a t i v i t i e s o f t h e h a l i d e i o n s ; the more
e l e c t r o n e g a t i v e h a l i d e i o n w i l l reduce e l e c t r o n d e n s i t y on the m e t a l , making
-50-
i t more s u s c e p t i b l e
to nucleophilic attack.
The
mechanism o f the
reaction
c o u l d i n v o l v e e i t h e r a r a p i d p r e - e q u i l i b r i u m i n s o l u t i o n between a d i b r i d g e d form and
a s i n g l e b r i d g e d species and
vacant c o - o r d i n a t i o n
s i t e , or the f o r m a t i o n
nucleophilic attack at
the
of a 7 co-ordinate a c t i v a t e d
164
complex.
M o n o s u b s t i t u t e d rhenium p e n t a c a r b o n y l h a l i d e s Re(C0) LX have been found
4
t o r e a c t w i t h a second l i g a n d L' a c c o r d i n g t o a f i r s t o r d e r r a t e e q u a t i o n ,
165
1
the r a t e b e i n g independent o f L , even a t h i g h c o n c e n t r a t i o n s .
The
rate
d e t e r m i n i n g s t e p appears t o be d i s s o c i a t i o n o f a CO
group from the complex.
The
N-ligands are found t o
l i g a n d , L, i n f l u e n c e s
the r a t e o f r e a c t i o n , and
have a l a b i l i z i n g e f f e c t on the CO
i s contrary
groups.
t o what would be p r e d i c t e d
As
e x p l a i n e d i n S e c t i o n F,
on jt-bonding arguments and
e x p l a i n e d i n terms o f s t a b i l i z a t i o n o f the t r a n s i t i o n s t a t e .
this
is
Rhenium
pentacarbonyl h a l i d e s also react according to a 1st order r a t e equation,
the r a t e - d e t e r m i n i n g
a second CO
4a.
step b e i n g d i s s o c i a t i o n o f a CO
Iron
2
u s u a l l y causes d i s p r o p o r t i o n a t i o n
unsubstituted
J
-
p
CO-OlaiLidLC
[Fe (C0)g]
2
Replacement o f
163
group t o g i v e the d i s u b s t i t u t e d complex i s v e r y r a p i d .
D i r e c t r e a c t i o n o f Fe(CO),., F e ( C 0 )
.,_
group.
2-
g
leading
or F e . j ( C 0 )
UUL
L L i e ctm-Ono v-au
, or [FeCCO)^]
2-4
.
De
w i t h N-donor
t o complex i r o n c a t i o n s
c a r b o n y l f e r r a t e a n i o n s . The c a t i o n s
_~^"H 1 i _ ».i
j __,
x. _ m. / *ir\ \
re
12
i r e ^ v w / ^ l
ligands
and
u s u a l l y c o n t a i n 4- or
1 2r-n- / rtr\ \
1 2—
,
Lr
j
,
A few examples are g i v e n i n the e q u a t i o n s :
6-
-51-
T a b l e 1.3.
Rhenium and Technetium c a r b o n y l complexes
(i)
Rhenium c a r b o n y l d e r i v a t i v e s
Compound
Ref.
[Re(CO) py ]
3
2
2
[Re(C0) o-phen]
3
?
160
?
160
Re(C0) (o-phen)C0 CH
3
(ii)
(a)
2
162
3
Carbonyl h a l i d e d e r i v a t i v e s
Re(C0) LX
( b ) Re^CO^L^X
4
X
L
Ref.
X
1/
Ref.
Cl
NH
158
Cl
py
139,158,160,161,163
Cl
py
164
Br
py
160,163
Br
py
164
I
py
139,159,160,165
I
py
164
Cl
(H NC H )
Cl
y-pic
164
Cl
(HNC^Hg)
161
Br
y-pic
164
Br
HNC^Hg
161
I
y-pic
164
Br
y-pic
165
3
( c ) Re(C0)_L"X
2
6
158,161
5
( d ) Ionic Derivatives
Ref
Ref.
Compound
o-phen
158
[Re(CO) (NH ) ]Cl
Br
o-phen
160
[Re(CO) (NH ) ]BPh
I
o-phen
160
[Re(CO) (o-phen)] Zn Cl
Cl
bipy
163
[Re(C0) (o-phen)]Cl•HCl
162
Br
bipy
163
[Re(CO) (HNC H ) ]I
161
I
bipy
139
[Re(C0) (HNC H ) ]BPh
X
Cl
4
3
4
158
2
3
2
4
158
4
2
2
4
3
3
4
4
g
g
3
3
4
6
136
161
-52-
(iii)
(iv)
Mixed c a r b o n y l h a l i d e
derivatives
Compound
Ref.
ReCcoXjCpphjXpyX:!
165
Technetium
Compound
Ref.
Tc(CO) (HNC Hg) Cl
3
4
2
161
-53-
gas.NH„
Fe(CO),. i n p y r i d i n e
-» [ F e ( N H ) ] [ F e ( C O ) g ]
3
fi
2
liq.NH,
Fe (CO)
3
-» [ F e ( N H ) ] [ F e ( C O ) ]
1 2
3
6
3
1 1
1
[Fe(NH ) HFe (CO) ] + [Fe(NH ) ][Fe (CO) ]
3
_ , \
Fe (CO)
3
6
2
g
&
4
1 3
ethylenediamine^ „ ,
,,_ /„_\ , .
*
> [ F e ( e n ) ] [ F e ( C O ) ] + CO
40
en
r
1 2
3
x
3
3
1;L
90^
4
[Fe(en) ][Fe(C0) ] <
6
e
n
4
[ F e ( e n ) ] [ F e ( C 0 ) g ] + CO
p
3
2
145
+ CO
Me
Fe(C0)
5
+ 2,4-lutidine
> [Fe(N^
^-Me) ] [Fe (C0) ]
4
4
1
6
7
1 3
O f t e n t h e p r i m a r y o r secondary base r e a c t s w i t h e v o l u t i o n o f CO e.g. i n t h e
167
system F e ( C O ) / p i p e r i d i n e , [Fe(C H N-CHO) ] [ F e ( C 0 )
5
5
1()
6
4
1 ; }
] i s the product.
I n some cases, i n t e n s e l y c o l o u r e d adducts o f an amine w i t h Fe(CO),. have
been i s o l a t e d :
65°
Fe(CO),.
or F e ( C+O )o-phen
3
1 2
» Fe(C0 )j^80°
^ 'o-phen
i n soln.
166
h i g h temp.
py s o l n .
[Fe(o-phen) ][Fe (C0) ]
3
4
1 3
[Fe(o-phen) ][Fe (C0) ]
3
2
8
• 54-
Fe(CO) + p i p e r i d i n e •
5
> Fe(CO),.'3piperidine
I
[Fe(piperidine) ] [Fe (CO)
6
Fe(CO) + p y r r o l i d i n e
4
1;}
]
167
» Fe(CO) * 2 p y r r o l i d i n e
I
[ F e ( p y r r o l i d i n e ) ] [Fe^CCO)^]
167
6
80^
Fe(CO),. + p y r i d i n e - a l d e h y d e - ( 2 ) - a n i l
-> [Fe(CO),]
5 2
J
C
H
6 6
168
I n d i r e c t s y n t h e t i c methods must be employed t o prepare i r o n c a r b o n y l N9
donor d e r i v a t i v e s .
2
Fe(CO) -/N0 -,
4
1 6 9
2
7 2
have s t u d i e d t h e systems
1 7 2
and F e C C O ^ V N ^ O S C ^ .
H i e b e r and B e u t n e r ^ " ^
'
1 7 2
2
Fe(CO) -/NH OH
4
2
1 6 9
'
-
170
>
1 7 1
These systems a r e q u i t e complex, and a v a r i e t y o f p r o d u c t s can be o b t a i n e d
depending upon t h e exact c o n d i t i o n s .
a small amount o f a complex f o r m u l a t e d
However, under c e r t a i n m i l d
as [Fe(C0).jNH]
aqueous a l k a l i n e s o l u t i o n s as a red-orange s o l i d .
2
conditions
p r e c i p i t a t e s from
7
[FeCCO^NH^] * ^ has been
p r e p a r e d by t h e slow a d d i t i o n o f an a l k a l i m e t a l s a l t o f hydroxylamine-Osulphonic
a c i d t o an aqueous a l k a l i n e s o l u t i o n o f Fe(CO),. ( e x i s t s as
H F e ( C 0 ) ~ ) a t 0°C.
5
The y e l l o w c r y s t a l s , o f e m p i r i c a l f o r m u l a [FeCCO^NH^
7
separate i m m e d i a t e l y and a r e s t a b l e o n l y below 0°C.^"''"
-55-
The
complex [ F e ( C O ) N H ]
3
2
has been r e - i n v e s t i g a t e d r e c e n t l y and i s now
thought t o be a b r i d g e d amino-complex r a t h e r than a b r i d g e d imino-complex,
24a
on t h e b a s i s o f i . r . , n.m.r. and e s p e c i a l l y mass s p e c t r a l evidence.
24b
T h i s s t r u c t u r e has r e c e n t l y been confirmed by X-ray c r y s t a l l o g r a p h i c s t u d i e s .
A new p r e p a r a t i v e method i n v o l v e s i r r a d i a t i n g a s o l u t i o n o f Fe(CO),. i n
e
aqueous KOH t o which NaNC^ has been added.
^ 2^3 *
s
r
P °duced, t o g e t h e r w i t h
24 a
9*2% o f t h e amine.
R e a c t i o n o f t r i e t h y l p h o s p h i n e r e p l a c e s one CO group,
w i t h o u t d i s r u p t i n g t h e -NH b r i d g e s , t o g i v e [ ( C O ) F e ( N H > F e ( C O ) ( P E t ) ] .
2
The
3
s y m m e t r i c a l l y d i s u b s t i t u t e d PPh
3
2
2
2
3
complex, [ ( P P h ) ( C O ) F e ( N H ) ] , i s
3
2
2
2
o x i d i s e d by i o d i n e t o g i v e v i o l e t c r y s t a l s o f t h e s a l t
[(PPh )(CO) Fe(NH )]
3
2
2
2 +
2
2l".
2 4 a
173
Compounds o f t h e type F e ( C O ) L X
2
2
(L
2
= py , bipy; X = I ,
2
2
have been prepared, as shown i n t h e e q u a t i o n s :
C F F e ( C O ) I + excess py
'
¥
R , T
3
7
C H
-—>
fi
C F Fe(CO)
3
?
(C F ) Fe(CO)
3
7
2
3
+ bipy
4
7
4
6
90°
+ excess py =
4
(C F JFe(CO)
Heating
(C^^Tei^^py)^
4
(C F )Fe(CO) (bipy)l
3
2
» (C F ) Fe(C0) py
3
+ b i p y ^ - Z ^
7
7
2
2
2
(C F ) Fe(CO) bi y
3
7
2
2
P
the complex ( C F ) F e ( C O ) ( p y ) I causes decomposition t o
3
[Fe(py) ]
6
2 +
2r.
1 7 3
7
2
2
C^Fy)
-56-
n-CpFe(CO) Br r e a c t s w i t h A l B r
2
conditions
to give
3
i n l i q u i d S0
2
under r i g o r o u s l y
dry
+
O-CpFe(C0) -Br-(C0) Fejt-Cp] , i s o l a t e d as the PF
2
2
&
174
salt.
R e a c t i o n s o f t h i s s a l t w i t h N - l i g a n d s , L g i v e s the complexes
174
[n-CpFe(CO) L]PFg, where L = p y r i d i n e , b e n z o n i t r i l e and
2
aniline
, which
cannot be prepared by d i r e c t r e a c t i o n o f L w i t h [jt-CpFe(CO) Br] .
2
jt-bonded p y r r o l y l d e r i v a t i v e s o f manganese have been prepared by
a c t i o n o f p y r r o l e i t s e l f on Mn (CO)^Q 175,176
2
^
r e a c t i o n of
the
the
potassium s a l t o f p y r r o l e w i t h M n ( C O ) , . B r . T h e second method was extended
'2
t o jt-CpFe(CO)_I, w h i c h r e a c t s w i t h p y r r o l y l p o t a s s i u m t o g i v e a z a f e r r o c e n e
( i t - C ^ H ^ F e j t - C ^ H ^ N ) . o - b o n d e d i n t e r m e d i a t e s may be p o s t u l a t e d i n each case,
23
and
by
the d e r i v a t i v e s i n Fig.I.'9 have s i n c e been i s o l a t e d f o r the i r o n system
the r e a c t i o n o f
mild
rt-CpFe(CO) I
2
w i t h the a p p r o p r i a t e
potassium s a l t under
conditions.
OC
R = H,
Fe
CO
OC—— Fe
(pyrrolyl)
indole
R = COCH (2-acetylpyrrol-l-yl)
3
CO
OC
Fe
CO
carbazole
Also 1,2,3,4,-tetrahydro d e r i v a t i v e
Fig.I.9.
-57-
Heating
the cr-pyrrolyl and indole compounds causes l o s s of CO and formation
of the corresponding
jt-bonded complexes, though the ir-indoles a r e unstable
23
and have not been f u l l y c h a r a c t e r i s e d .
King and Bisnette''"^"' have prepared an a c y l h e t e r o c y c l i c compound of
[ n - C p F e C C O ^ ^ j analogous to the manganese carbonyl
105and c y c l o p e n t a d i e n y l molybdenum carbonyl d e r i v a t i v e s described e a r l i e r
Reaction of
NaFe(CO) ir-Cp and ClCH CH NMe
2
2
only as a minor
2
2
gave the c y c l i c a c y l d e r i v a t i v e
product.
^CH
-N'
CH„
0
c
3
•Fe<
(Fig.I.10a)
^_ J
F
CH
3
c
_ i _ H — C H — I -We
e <
C
c
0
2
2
4H„
C H
3
C1'H 0
2
g
(b)
(a)
Fig.I.10.
The major product was an i o n i c d e r i v a t i v e , given the formulation shown i n
Fig.I.lOb.
However, r e a c t i o n of NaFe(CO) jt-Cp with 2 - c h l o r o e t h y l p i p e r i d i n e ,
2
and 2-chloromethylpyridine gave C,.H NCH CH Fe(CO) Jt-Cp and
10
2
2
2
NC^H^CH Fe(CO) Jt-Cp, r e s p e c t i v e l y , which c o n t a i n only o-C-Fe bonds, i n c o n t r a s t
2
2
to the jt-CpMo and Mn d e r i v a t i v e s . ^ ^
The thiocyanate i r o n carbonyl d e r i v a t i v e [Fe(C0)^NCS] ~ has been i s o l a t e d
as i t s (Ph.jP) N
2
+
salt.''"'^
The thiocyanate group i s nitrogen bonded and no
-58-
i s o m e r i s a t i o n was observed.
Both the S-bonded and N-bonded isomers of
jt-CpFe(CO)_(CNS) were prepared by the a c t i o n of HPF, and KSCN on
z
o
118
[jr-CpFeCCO^] ^-
N
o
r e a c t i o n occurred with the h a l i d e s
rt-CpFeCCO^X.
The S-bonded isomer, when warmed gently e i t h e r i n the s o l i d s t a t e or i n
suspension i n e.g. Nujol, isomerises to the N-bonded isomer, but i n s o l u t i o n ,
. „
118
i t decomposes.
Recently, there has been much i n t e r e s t i n r e a c t i o n s between i r o n
carbonylsand compounds containing nitrogen atoms i n unsaturated systems.
Many of the products have unusual s t r u c t u r e s , which have been e l u c i d a t e d by
X-ray methods.
Manuel^isolated
a complex from the r e a c t i o n between
phenyl isocyanate and Fe^CCO).^ which he formulated as [Fe(CO) CgH^NCO]^.
3
The same complex was prepared by the treatment of Fe^CCO).^ with azido benzene
CgH^N^, and the analogous b u t y l i s o c y a n a t e complex was a l s o prepared.^''
The
s t r u c t u r e of the complex was thought to be:
R
\
/
0
<p
Fe—-CO
/ N o
\
<r
11
\ /
0C - — F e
x
177
\ /
o r
P
h
N
F
~
/
e
c
\
0
\
F
/
e
/
N
P
h
\
R
Pauson e t a l have r e c e n t l y re-examined the Fe^(C0) /PhNC0 r e a c t i o n , and have
1?
a l s o made the e t h y l i s o c y a n a t e d e r i v a t i v e .
They formulate the complexes as
(RN)2Fe2(CO)^ from a n a l y t i c a l and mass s p e c t r a l data.
178
shows that the i r o n atoms are e q u i v a l e n t ,
Mossbauer spectroscopy
and an X-ray study has
-59-
confirmed the s t r u c t u r e I.11a for the complex, /j-diphenylureylene-bis( t r i c a r b o n y l i r o n ) . -1-79,180
c o m p
two nitrogens and thus resembles
^
e x
c o n
t ins
a
two Fe(CO)^ u n i t s bridged
by
other complexes mentioned below.
I r r a d i a t i o n of diaryldiazomethanes with Fe(CO),. gives
products
containing nitrogen and not products derived from the d i a r y l c a r b e n e s ,
expected
181
as intermediates.
The same products are obtained by a thermal r e a c t i o n
181
using Fe^(C0)^2*
Both diphenyl- and di-p-tolyl-diazo-methanes gave black
1
1
complexes (A and A , r e s p e c t i v e l y ) and orange complexes (B and B ,
181
respectively).
Mass and n.m.r. s p e c t r a of B and B' showed these complexes
to have the formulation [I^CH^FeCCO)^] ^
a n <
*
a n
X-ray s t r u c t u r a l
examination
1
of B'showed the complex to be bis-(/i-4 ,4 -dimethylbenzophenonehydrazonatot r i c a r b o n y l i r o n ) , with the s t r u c t u r e shown i n F i g . I . l i b .
Again, two Fe(CO)^
u n i t s are bridged by two N atoms and, as observed i n r e l a t e d compounds, the
3
Fe-Fedistance i s short. The N atoms are sp h y b r i d i s e d , the Fe-N bonds
being e s s e n t i a l l y s i n g l e . The c r y s t a l s t r u c t u r e of one of the b l a c k ,
i n v o l a t i l e complexes, A, obtained i n greater y i e l d i n the r e a c t i o n , has a l s o
182
been determined
and i s shown i n F i g . I . 1 1 c .
The complex,
(Ph2C=N-N)2tFe(CO)2]^ i s the f i r s t compound with a nitrogen atom
simultaneously and e q u a l l y bridging three metal atoms, and can be
regarded
as a bridging hydrazone complex i n which both terminal hydrogens have been
182
replaced.
replaced.
I n the orange complex, only 1 terminal hydrogen had been
Two
Fe-Fe d i s t a n c e s are much shorter than the t h i r d and bond
182
lengths i n d i c a t e s i n g l e N-N
and double C=N
bonds.
Fig.I.11.
R
N
N
(CO)„Fe
Ph
Fe(CO)
3
178,179,180,186
H-Diphenylureylene-bis(tricarbonyliron)
„
186,186a
R • Me
'
M
R C
l
6 V
R
W
N
H
R
W
H
N
(C0) Fe
Fe(CO),
3
R = H (B)
R = p-Me
181
(B')
181
bis{/i-4,4' -dimethylbenzophenone
hydrazonatotricarbonyliron)
(b)
Fig.I.11.
Ph
N
Ph
N
Fe(CO)
(COLFe
Fe(CO)
(CO)„Fe
CH
N
N
Ph
Fe
(CO)
Ph
182
(c)
R
p-MeC,H
183
(d)
(CO)
di-/i(4,4' -dime thy lbenzophenon
1
iminato)bi8(tricaronyliron) ^^
^-N.N'dehydrosemidinato
.. . .
.
, .
,.183,184
bis(tricarbonyliron)
'
(e)
(f)
Fig.I.ll.
R.
(CO) Fe
Fe(CO),
3
R = Ph
(CO)„Fe*-
186
Fe(CO)
R = Ph
bis4/i-phenylamidotrlcarbonyl,
.186
iron)
(g)
„ 186
R = Me
n
(h)
(CO)
Fe
v
,.N—N
N*
(CO) Fe/
:Fe(CO),
3
A >
Me—N \
/
Fe'
(COL
7
„N=N,
N—Me
N—Me «
» Me
k
/
F
(CO),
Me
(i)
(ii)
186,186b
186
(i)
(j)
CH„
x,CH—CH
-/
R—CH \ ^ ^ / ^ N — R '
Fe
(co)
(i)
(ii)
k
Fe'
(CO),
3
R = R' = Ph
2
5
,
1
8
7
(i)
R = CH ; R' = n-C H
3
4
(k)
\N—R
25
9
(ii)
R = C H
g
25
5
R = n-C^Hg
(1)
25
Fig.I.11.
N=CHC,H
'I
6 5
C
CC77
Fe
I
Fe
(co) (co)
3
Fe. Fe
(co) (co)
3
3
3
25
(m)
(i)
(ii).
R - R' = Ph
R = Ph; R
(n)
OC
Fe
HCH
189
(o)
CO
1
188
- Me
188
Fig.I.11.
<3>
w
NH
CF
N
CF
H
N
CO
Fe
Fe
(CO)„ (CO)
190
(p)
191
(q)
(CO)
/
(CO)
Fe
\H
CO
or
(CO).Fe
l\
Fe
CO
/\
(CO),Fe
NMe
ii)
192
(r)
Ar
X
Fe(CO)
CO
NMe
(i)
(CO)„Fe
/
CO
CO
0 = N
H
Oc
N
\ /
N=0
'Fe'
(CO)
193,194
194
(s)
(t)
Ar
CO
-60-
Reaction of S c h i f f bases with Fe2(C0)g produces Fe2(C0)gL complexes.
The complex formed with the base C H ^ — ^
^—N=CHPh (prepared from p-
t o l u i d i n e and berealdehyde) has been shown by X-ray
techniques to have the s t r u c t u r e I . l i d .
by a nitrogen atom.
183
crystallographic
Again two Fe(CO)^ u n i t s are bridged
One Fe atom i s p a r t of a 5-membered r i n g which i n c l u d e s
the N-atom and one s i d e of the benzene r i n g .
The other Fe atom i s
considered to it-bond to one of the o l e f i n i c bonds i n the benzene r i n g .
Again, a short Fe-Fe d i s t a n c e i s observed and the nitrogen i s considered to
183
be a 3 - e l e c t r o n donor.
The complex formed from the r e a c t i o n of Fe2(C0)g
with azobenzene (Ph-N=N-Ph) has a d i f f e r e n t s t r u c t u r e , shown i n F i g . I . l i e ,
i n which both nitrogens bridge the two Fe(C0).j u n i t s , which are arranged
183 184
i n an e c l i p s e d c o n f i g u r a t i o n .
'
The Fe-Fe d i s t a n c e i s very short.
Thus formation of the complex i n v o l v e s rupture of the -N=Narrangement to form the o-semidine skeleton.
bond with r e -
A 36 e l e c t r o n s t r u c t u r e can
be r a t i o n a l i s e d on the supposition that each nitrogen a c t s as a three
183
e l e c t r o n donor.
184
'
The benzene r i n g s are not involved i n bonding to
the metal atoms i n t h i s complex.
1
I n the r e a c t i o n of 4,4 -dimethylbenzophenoneazine,
(p-Me-C H ) C=N-N=C(p-MeC H^) , with F e ( C 0 > , rupture of the =N-N= bond occurs
6
4
2
6
2
5
to give the complex [ (p-MeCgH^ )£N-Fe(C0).j] ^ > whose s t r u c t u r e i s shown i n F i g .
185
I.llf.
S p l i t t i n g of the N-N
bond a l s o occurs i n r e a c t i o n of azo-benzene
with Fe2(C0)g, but, whereas i n that case rearrangement to the o-semidine
skeleton occurs, here the moieties are trapped i n the complex s e p a r a t e l y .
-61-
Again a short Fe-Fe d i s t a n c e i s observed, as i n a l l nitrogen bridged i r o n
carbonyl d e r i v a t i v e s .
The r e l a t i v e l y short Fe-N d i s t a n c e allows the
2
assumption of sp
h y b r i d i s e d n i t r o g e n atoms, each of which a c t s as a 3
e l e c t r o n donor.
Dekker and Knox have studied the decomposition of azido-benzene,
186
c a t a l y s e d by Fe2(C0)g.
Thermal decompositions of many azido-compounds i n
i n e r t media are very slow processes even a t high temperatures, but the
c a t a l y s e d r e a c t i o n s occur r a p i d l y under mild conditions.
Azidobenzene
Fe2(C0)g r e a c t r a p i d l y at room temperature i n benzene s o l u t i o n .
azobenzene
i s produced,
and
Very l i t t l e
the p r i n c i p l e product being (PhN)2Fe2(CO)g, which i s
assigned s t r u c t u r e I . l l g , on the b a s i s of mass, n.m.r., i . r . and Mossbauer
spectroscopy.
Spontaneous
decomposition of I . l l g i n s o l u t i o n g i v e s I.11a,
fi-diphenylureylene-bis(tricarbonyliron).
Manuel^"^ reported the compound
[Fe(CO) CgH^NCO]2 formed from azidobenzene and F e ^ C C O ^ j but h i s product
178 179
3
was l a t e r shown to be I.11a, (R = Ph).
'
Also formed during the
c a t a l y s e d decomposition of azidobenzene i s the complex (PhNH)2Fe2(CO)g,
assigned the s t r u c t u r e I . l l h and obtained only i n low y i e l d i n one of i t s
186
expected isomeric forms - probably the "semi-trans" c o n f i g u r a t i o n shown.
Addition of Fe^CcO).^ to a benzene s o l u t i o n of azidobenzene causes very r a p i d
decomposition, with the formation of s i g n i f i c a n t amounts of azobenzen'e and
186
azoxybenzene.
An extensive range of complexes i s obtained from methyl-
azide and Fe2(C0)^; (CH.jN)2Fe.j(C0)g i s assigned s t r u c t u r e I . H i by analogy
186
with S2Fe.j(C0)g
and other minor products include isomeric forms of
/j-methyl-amido complex I . l l h , (R = Me).
The major product of the r e a c t i o n i s
-62-
1.11a (R = Me), b e t t e r obtained from methylisocyanate and Fe2(C0)g
186
, and
the s t r u c t u r e of t h i s complex has r e c e n t l y been confirmed by X-ray
186a
crystallographic studies.
A compound Me2N^Fe(C0)^ was a l s o obtained,
186
which i s assigned s t r u c t u r e I . l l j
on i . r . , n.m.r. and mass s p e c t r a l data.
The t r i n u c l e a r species I . H i i s a l s o obtained from the v i o l e n t r e a c t i o n of
1 86
CH N0 with F e ( C O )
3
2
2
products.
a carbonyl.
g
, I.11a (R = Me) and I . l l h (R = Me) being minor
The r e a c t i o n i s notable for the reduction of a n i t r o compound by
The s t r u c t u r e of the t r i n u c l e a r s p e c i e s , I . H i , has been
186b
confirmed by X-ray c r y s t a l l o g r a p h i c s t u d i e s .
Each of the above r e a c t i o n s involving azido-, isocyanate,
and n i t r o -
compounds i s i n d i c a t i v e of a c a t a l y t i c generation of n i t r e n e s and the nature
of the products strongly suggests t r i p l e t n i t r e n e .
The scheme below can
account for the formation of the products.
RNCO
RN
N
RNO
CO
[M(CO)
R— N
solvent
RNCO
II
R-N-C-N-R
RN
RNH
R-N-N=N-N-R
I.llh
I.llg
and I . H i
1
I.Hi
M(CO) + C O J
-63-
Studies of azo-methine analogues of 1,3-dienes i n t h e i r r e a c t i o n s with
25
i r o n carbonyls have been undertaken
the metal and the l i g a n d .
to i n v e s t i g a t e the bonding between
Three unsaturated systems were studied:
-CH=CH-CH=N- (e.g. cinnamaldehydeanil and crotonaldehyde-n-butylamine),
-N=CR-CR=N- (e.g. d i a c e t y l a n i l and d i a c e t y l - n - b u t y l i m i n e ) , and -CH=N-N=CH25
(e.g.
benzalazine and a c e t a l a z i n e ) .
with cinnamaldehydeanil
structure I . l l k ( i ) .
Fe2(C0)g and F e ^ C O ) ^ both reacted
to give (PhCH=CH-CH=NPh)Fe(CO) which has the
3
Fe2(C0)g with crotonaldehyde-n-butylimine gave the
analogous compound I . l l k ( i i ) , which i s an a i r - s e n s i t i v e l i q u i d .
Reaction
with PPh^ displacedcne CO group i n I . l l k ( i i ) , but d i s p l a c e d the ligand i n
I.llk(ii).
aniline.
to
I . l l k ( i ) can a l s o be prepared from(cinnamaldehyde)Fe(CO)^ and
D i a c e t y l a n i l and d i a c e t y l - n - b u t y l i m i n e both reacted with Fe2(C0)g
give the compounds I . l l l ( i ) and I . l l l ( i i ) ,
Fe (C0)
2
respectively.
Benzalazine and
gave (PhCH=N-N=CHPh)Fe (C0) , I.11m, but a c e t a l a z i n e gave a very
g
2
6
unstable product.
The s t r u c t u r e shown for I.11m i s very t e n t a t i v e . I.R.
25
and n.m.r. evidence i s the b a s i s for the s t r u c t u r a l assignments
, but an
187
X-ray s t r u c t u r a l study
on I . l l k ( i ) , has confirmed that the bonding i s
s i m i l a r to that found i n conjugated d i - o l e f i n complexes, and that the
187
nitrogen lone p a i r does not play a s i g n i f i c a n t part i n the bonding.
.
188
A r e l a t e d type of complex contains the ^C=C=N- skeleton.
N-phenyldiphenylketenimine and N-methyldiphenylketenimine r e a c t with
Fe (C0)
3
t o
1 2
produce the compounds [(Ph2C=C=N-R)Fe (C0) ], where R = Ph and
R = Me, r e s p e c t i v e l y .
2
6
Triphenylphosphine d i s p l a c e s one CO group from each
-64-
complex, r a t h e r than the l i g a n d .
The s t r u c t u r e s of the complexes, shown i n
I . l l n ( i ) and ( i i ) , are based on i . r . and n.m.r. evidence, and assume
p a r t i c i p a t i o n of both C=C and C=N
double bonds.
Reaction between Na[rt-CpFe(CO) ] and chloromethylisocyanate g i v e s a
2
mixture of products, from which a small amount of m a t e r i a l , corresponding to
189
(jt-Cp) Fe (CO)^(CH NCO), may
3
3
2
be i s o l a t e d .
189
On the b a s i s of i . r .
n.m.r. s p e c t r a data, King and B i s n e t t e
I.llo.
and
have suggested the novel s t r u c t u r e
I n the i n d i c a t e d d i p o l a r resonance s t r u c t u r e of the NCO
group, the
carbon-nitrogen t r i p l e bond i s i s o e l e c t r o n i c with the carbon-carbon t r i p l e
189
bond i n a c e t y l e n e s , which i s known to bridge i n t h i s manner.
Trifluorophosphine i s analogous to CO i n i t s rt-acceptor p r o p e r t i e s and
190
r e c e n t l y t r i f l u o r o a c e t o n i t r i l e has been studied f o r the same reason.
CF CN and CH Fe(CO) rt-Cp r e a c t to give CF C(NH)Fe(CO)(NCCF )it-Cp.
3
3
2
3
3
The
19
" e x t r a " proton on the nitrogen i s observed i n the n.m.r.
F n.m.r. and mass
s p e c t r a l evidence i n d i c a t e the s t r u c t u r e I . l i p and the high carbonyl
absorption i n the i . r . spectrum
,
„
190
of the CF C=N group.
n
i n d i c a t e s the strong jr-acceptor p r o p e r t i e s
>T
3
A compound Fe„(C0),C-H,SNH
/
o b i\
N
>>H»
Fe(C0)
3
191
, i s o l a t e d from the r e a c t i o n of o-amino-
with F e ( C 0 ) , i s supposed to contain two
3
1 2
u n i t s bridged by both a sulphur and a nitrogen atom ( s t r u c t u r e
191
1.11^).'
Reaction between F e C O )
3
1 2
-0
and C ^ C ^
i n dimethyl formamide
192
leads to a compound H F e ^ C O ^ N l f e ^
incorporated into the F e ( C 0 )
3
1 2
i n which H and NMe have been
2
s t r u c t u r e with l o s s of one CO group.
The
-65-
s t r u c t u r e of the complex i s thought to be e i t h e r I . l l r ( i ) or I . l l r ( i i ) .
192
Studies of o r g a n o n i t r i l e / i r o n carbonyl systems have shown that heating
Fe (CO)
0
Q
and PhNO_ g i v e s the corresponding organonitroso ironcarbonyl
d e r i v a t i v e [ P h N O F e C C O ) ^ ] ^ . I r r a d i a t i o n with a ^^Co source, of an
acetone s o l u t i o n of Fe(CO),. and PhNC^ g i v e s the same product, whereas
s i m i l a r treatment of Fe(CO)^ with PhNO i t s e l f g i v e s no organo-ironcarbonyl
derivatives.
The i . r . of the dimeric compound shows no bridging CO groups,
and the s t r u c t u r e I . l i s i s proposed.
via
The r e a c t i o n i s thought
to proceed
i n i t i a l formation of a nitrobenzene i r o n t e t r a c a r b o n y l complex,
PhlTC^FeCCO)^, which i s reduced by CO to the dimeric nitroso-complex.
s i m i l a r r e a c t i o n path was proposed
A
for the formation of [Fe(CO).jNO] ~ from
- 172
[FeCCO^ClK^)] .
Studies on the e f f e c t of s u b s t i t u e n t s i n the benzene
r i n g of nitrobenzene have shown that e l e c t r o n donating groups i n o- or pp o s i t i o n s encourage the formation of monomeric nitroso-compounds,
194
(X-C,H.NO)Fe(CO).,
with the s t r u c t u r e I . l i t .
Reaction of the dimeric
compound with a n i l i n e i n methanol/glacial a c e t i c a c i d g i v e s azobenzene, p193 194
t o l u i d i n e g i v e s 4-methylazobenzene.
'
T h i s type of complex may serve
as a s t a b l e source of n i t r o s o compounds.
Triphenylphosphine d i s p l a c e s a CO
group from the dimer, g i v i n g monomeric PhN0Fe(C0)2PPh.j.
Although
i t has long been known that amines u s u a l l y cause d i s p r o p o r t 195-199
ionation of i r o n carbonyls, recent s t u d i e s of these, and r e l a t e d
systems
have'provided some i n s i g h t i n t o the mechanisms of these r e a c t i o n s .
1
2 , 2 , 2 " - T r i p y r i d y l ( t r i p y ) d i s p l a c e s the c y c l o p e n t a d i e n y l group from
-66-
t
[ jt-CpFeCCO^] 2
secondary
o
give FeCCO^tripy.
amines on
a t t a c k by
The
a c t i o n of p r i m a r y
[ i r - C p F e C C O ^ L ] * ( L = CO,
of t h e t y p e jt-CpFe(CO)L(CONHR).
initial
195
The
PPh^) g i v e s carboxamido c o m p l e x e s
r e a c t i o n i s thought to p r o c e e d
the n i t r o g e n l o n e p a i r on
g r o u p s , f o l l o w e d by p r o t o n
and
t h e C atom of one
via
of the carbonyl
loss.''"^
19 7—198
E d g e l l and h i s c o - w o r k e r s
h a v e made a c a r e f u l s t u d y of t h e
197
s t a g e s of r e a c t i o n between Fe(CO),. and n - b u t y l a m i n e
initial
197
, piperidine
and
, ...
198
.
.
197,198
198
. . 197,198
pyrrolidine
, using l . r .
, n.m.r.
and c o n d u c t i v i t y
techniques.
During
t h e r e a c t i o n 3 c a r b o n y l s p e c i e s were observed, A,
I n t h e c a s e of p i p e r i d i n e , A was
anion HFe(CO)^
i s o l a t e d and
The
-
and C was
formulated
C^H^QNHFe(CO)^.
B and
a s Fe(CO)^(NHC^H.|^).j, B was
F o r p y r r o l i d i n e , compound A
the
was
shown to be Fe(C0)g(C^HgN)2, p r e v i o u s l y p r e p a r e d by Hieber.''"^^
compound i s i o n i c i n n a t u r e and
t h e l i g a n d c o n t a i n s an amide l i n k a g e
198
^NCO-.
HFe(CO)^
Thus t h e amine h a s a t t a c k e d the c a r b o n
i s formed from w a t e r
atom of a c a r b o n y l group.
i n t h e amine - more r i g o r o u s d r y i n g
resulted
197
i n no H F e ( C O ) ^
b e i n g formed.
The
mechanism f o r the room t e m p e r a t u r e
authors
p o s t u l a t e the f o l l o w i n g
r e a c t i o n o f amines w i t h F e ( C O ) ^ :
C.
-67-
H
0
II
R n—C-Fe(CO)
Fe(CO),. + R„NH
(A)
+
R„NH
trace of
H-0
Fe(CO)
R_N
+ R~NH
(B)
R_NH„[HFe(CO).]
R„NH
R_NH
R.N
R_NHFe(CO), + R„N-CHO
R„NHFe(CO), + CO
(carbamate)
(C)
(C)
+ R-NH
199
B u l k i n and Lynch
have attempted to confirm the i d e n t i t y of species C,
by r e a c t i n g ( d e f i n e ) F e ( C O ) ^ complexes with p y r r o l i d i n e .
An intermediate
was formed immediately, which was slowly converted into a species with an
198
i . r . spectrum i d e n t i c a l to E d g e l l ' s compound C.
reacted immediately to give
(olefine)Fe(CO)^ +
Fe (CO)
2
g
+
f^NH
1
11
[^y *
Fe(CO)
5
+
T
the same compound:
y
intermediate
» ^\Fe(CO)
_
Fe2(C0)g and p y r r o l i d i n e
+
4
• ^^^Fe(CO)^ + define
[^^NFe(CO)
5
0
\H
> [
NCFe(CO)
0
/!(
) T
NFe(CO) +
4
T
NCH
A l l attempts to i s o l a t e the products, however, l e d to decomposition. 199
-68-
4b.
Ruthenium and Osmium
The simple carbonyls of ruthenium
and osmium have not been reported to
combine with nitrogen l i g a n d s , but s e v e r a l organonitrogen
d e r i v a t i v e s are known.
[RuCCO^^l
carbonyl h a l i d e
i s a polymeric m a t e r i a l , but i t w i l l
r e a c t with l i q u i d ammonia and other n i t r o g e n - l i g a n d s a t higher
temperatures
1
to give the complexes R u C C O ^ ^ ^ ' where L = NH^, p y r i d i n e , a n i l i n e , pt o l u i d i n e , a c e t o n i t r i l e , and where
in addition
condensing
= bipyridyl.^^
Hieber and Hensinger^''',
to the py, bipy and NH^ d e r i v a t i v e s , prepared R u ^ O ^ ^ e n by
ethylenediamine onto [ R u C C O ^ l ^ ] -
The NH^ and ethylenediamine
n
compounds are unstable i n s o l u t i o n , above -30°C and 20°C r e s p e c t i v e l y .
The
analogous osmium compound OsCCO^l^Py^ has been prepared from [05(00)2X2] 2
andA excess p y r -Ai d i n e . 202
The ruthenium
carbonyl c h l o r i d e dimer [RuCCO^Clg] 2
w
a
s
obtained by the
a c t i o n of CO ( a t 10 atmospheres p r e s s u r e ) on a methanolic s o l u t i o n of
203
RuCl '3H 0.
3
The carbonyl was i s o l a t e d i n i t i a l l y as the THF
2
adduct
( C , H 0 ) R u ( C 0 ) C l and r e a c t i o n of t h i s with py or bipy i n THF gives
4 o
3 2.
203
204
p y R u ( C 0 ) C l 2 and bipy R u ( C O ) C l r e s p e c t i v e l y .
Wilkinson and co-workers
Q
2
o
o
2
2
2
obtained a deep red s o l u t i o n of [Ru(C0).jCl] 2 by the a c t i o n of CO on an
ethanolic
s o l u t i o n of RuCl^-nl^O.
They did not i s o l a t e the complex, however,
but added an e t h a n o l i c s o l u t i o n of the appropriate amine to give the
complexes R u ( C 0 ) C l L
o
o
o
where L = C,H NH , C,H CH_NH and L
0
R
0
0
= bipy, o-phen.
R u C l ^ n l ^ O and L i B r i n ethanol with CO gave a green s o l u t i o n , and
addition
of amines to t h i s gave the corresponding bromine complexes R u f a O ^ B ^ I ^ ,
-69-
L = CgH^Nl^j CgHj-CI^Nh^ and
with anhydrous S n C l
= o-phen.
or SnBr
2
R e f l u x i n g the red or green s o l u t i o n s
r e s p e c t i v e l y , and subsequent a d d i t i o n of
2
p y r i d i n e gave [Ru(py) (CO) (SnX,j ) ^ \ X = C l , Br.
2
l^X*—NH
2
i n
,
2
Addition of o-amino-thiophenol
ethanol to the red s o l u t i o n gave [ R u ( C O ) ( C H ^ ( S ) N H ) ]
2
6
2
2
SH
i n which the l i g a n d
JJ
%
1
NH
^
S
a c t
n
^ 8
a s
a
uninegative bidentate
204'
ion.
Although the a c t i o n of p y r i d i n e i n ethanol on a freshly-prepared red
s o l u t i o n gives c i s [ - R u ( C O ) C l ( p y ) ] , i f the red s o l u t i o n i s allowed to "age"
2
2
2
for 24 h r s . before the a d d i t i o n of p y r i d i n e , a complex [pyH][RuCl^(C0)py]
can be i s o l a t e d .
No evidence for the formation of [RuCl (CO)py.j] i n the
former r e a c t i o n was
2
found, but norbornadiene or cyclo-octa-1,5-diene with the
205
red s o l u t i o n gave complexes of e m p i r i c a l formula [ R u C l ( C O ) ( d i e n e ) ]
and
2
treatment of these with p y r i d i n e gave [RuCl (CO)py.j] .
2
3-Methylpyridine
with the f r e s h l y prepared red s o l u t i o n gave cis[-RuCl (CO) (CH.j-C,-H, N)] but
205
quinoline gave t r a n s t R u C l ( C O ) ( q u i n ) ] .
The dicarbonyl d i h a l i d e s of Ru** can be r e a d i l y prepared by r e f l u x i n g
206
RuCl^ i n formic a c i d i n the presence of the appropriate h y d r o h a l i c a c i d .
The R u ( C 0 ) X complexes r e a c t r e a d i l y with l i g a n d s to give R u ( C 0 ) X L
2
2
2
2
2
i
2
2
2
206
complexes, RuCl (CO) (p-CH CgH^NH ^having been c h a r a c t e r i s e d .
2
2
3
2
2
2
2
-70-
I n t h e i r i n v e s t i g a t i o n of the r e a c t i v i t y of Ru^CCO)^ Chandlin and co207
workers
obtained an i n s o l u b l e polymeric m a t e r i a l from the a c t i o n of moist
NO on Ru^CCO)^-
0
n
t
n
e
b a s i s of i t s i . r . spectrum,
they formulated the
207
complex as a n i t r i t e , of e m p i r i c a l formula [ R u C C O ^ C l K ^ ^ ] •
5.
Cobalt, Rhodium and I r i d i u m
Strong bases cause ready d i s p r o p o r t i o n a t i o n of c o b a l t carbonyls to give
4
the t e t r a c a r b o n y l c o b a l t a t e anion:
3Co.(C0) + nB
Z
o
• 2[Co(B) ][Co(C0).]„ + 8C0
n
M- Z
Q
3 C o . ( C O ) + nB
h
1Z
> 4[Co(B) [Co(CO). ]„ +
n
i\ Z
10
( i f n = 6)
4C0
Reactions of the c o b a l t carbonyl s with l i q u i d ammonia have been studied
208
at room temperature.
the f i r s t g i v i n g [ C o
With ( ^ ( C O ^ , two r e a c t i o n paths are followed,
+ I I
- I
( N H ) g ] [ C o ( C 0 ) ^ ] ^ + CO, and the second g i v i n g
3
I
NH^]Co~ (C0)^] and urea (by r e a c t i o n of CO evolved with NH ).
3
Co^(C0)
1 2
r e a c t s to give the same products, but only a very small amount of
NH^lCo'^CO)^] and urea are produced, most of the Co^(C0)^2 r e a c t i n g v i a the
_
08
f i r s t pathway.
2
C o ( C 0 ) ( N 0 ) , obtained from a c i d i f i e d mixtures of Co(CO)^" and N0 ~,
3
2
209
r e a c t s with N-ligands w i t h displacement of two CO groups.
210
'
Thus
209
p y r i d i n e gave Co(N0)(C0)py2 i n s o l u t i o n , which could not be i s o l a t e d
,
. 2nQ 210
but o-phen and bipy gave the more s t a b l e d e r i v a t i v e s Co(N0HC0)o-phen
'
209
and Co(N0)(C0)bipy.
Reaction of Co(C0).jN0 with mixed phosphorus nitrogen
-71-
l i g a n d s (e.g. Et2NC2H^P(Ph)C2H^NEt2) gave only d e r i v a t i v e s with phosphorus
221
attached to the metal.
T h i s i s an example of a metal i n a low oxidation
s t a t e ( a " s o f t " a c i d ) p r e f e r r i n g to co-ordinate to a " s o f t " base ( ^ P )
221
r a t h e r than a "hard" base ( ^N).
Using an i n d i r e c t method i n an attempt to s y n t h e s i s e c o b a l t carbonyl
212
N-ligand compounds, Behrens
and
Aquila
reacted (CgHg^CoCCO)^
(C,H_ = cyclohex-1,3-diene) with bipy, o-phen and t r i p y
b o
1
(2,2 ,2"-tripyridyl)
i n r e f l u x i n g benzene, but obtained only the d i s p r o p o r t i o n a t i o n products
[ C o ^ L ^ ] [Co^CcO)^] .
However, under the same conditions ( n o r - C ^ H g ^ ( ^ ( C O ) ^
(nor-C^Hg = norbornadiene) gave, with bipy, ( ^ ( C O ^ C b i p y ^ i n 1007 y i e l d ,
o
and with o-phen, (^(CCO^Co-phen^ and some [Co(o-phen)^] [Co(CO)^] .
t r i p y , only the s a l t [ C o ( t r i p y ) ^ ] [ C o ( C O ) ^ ] could be obtained.
i.r.
With
From t h e i r
s p e c t r a the complexes COgCCO)^!^ were shown to have a c i s - c o n f i g u r a t i o n ,
212
with bridging carbonyl groups,
as shown i n F i g . I . 1 2
C
C
N
\
N
« —-V-.U
\ „N
N
//
0
Fig.I.12
J
-72-
A complex of e m p i r i c a l formula
(jt-CgH.-Co^CNl^^CO was one of the
products of the r e a c t i o n between n-CpCoCCO^ and N-t-butylsulphuriimide,
213
(t-C^HgN^S.
Mass and i . r . s p e c t r a l evidence suggests that the compound
contains an a l k y l u r e a group, whose nitrogen atoms bridge the two c o b a l t
213
atoms.
.
diffraction
J
>
f
£
T h i s structure,shown i n Fig.1.13, has been confirmed
j 214
study.
(CH ) C
3
C
3
^C(CH )
3
by an X-ray
3
Fig.I.13.
T h i s s t r u c t u r e i s s i m i l a r to the s t r u c t u r e of the i r o n compound, /i-diphenyl179 180
ureylene-bis(tricarbonyliron), Fig.I.11a.
There a r e comparatively
'
few c o b a l t carbonyl d e r i v a t i v e s containing a
nitrogen atom attached to the metal.
Direct
r e a c t i o n of bases with cobalt
carbonyls causes d i s p r o p o r t i o n a t i o n , and very few i n d i r e c t s y n t h e t i c methods
have been attempted.
As described e a r l i e r , though, COgCCO^ i s a c a t a l y s t i n
many organic r e a c t i o n s , i n c l u d i n g r e a c t i o n s of nitrogen compounds, and i n
the l a t t e r , the f i r s t step i n the mechanism i s thought to be co-ordination
36
of the organic compound to the c o b a l t v i a the nitrogen lone p a i r .
-73-
There have been no r e p o r t s of the d i r e c t r e a c t i o n of N-bases with the
rhodium and i r i d i u m carbonyls themselves, but, i n c o n t r a s t to c o b a l t , simple
carbonyl h a l i d e d e r i v a t i v e s of Rh and I r are r e a d i l y a v a i l a b l e and have
215-227
proved u s e f u l i n preparing compounds with nitrogen attached to the metal.
215
Reaction of [ R h ( C O ) C l ]
2
2
with p y r i d i n e gave R h ( C O ) p y C l , which Hieber
2
suggested was dimeric, to account for i t s diamagnetism.
2
Reaction w i t h other
ligands e.g. p i p e r i d i n e , o-phen and alkylamines gave i n d e f i n i t e products and
215
216
Ph^N did not r e a c t .
Wilkinson and Lawson
found that amines s p l i t the
bridges i n [ R h ( C O ) C l ]
2
2
and [ R h ( C O ) M e C 0 ]
2
2
to give d i c h r o i c , mononuclear
2
s p e c i e s which are decomposed by moisture to i l l - d e f i n e d
solids.
straw-coloured
The complexes prepared were Rh(CO) Cl*L where L = NH^, NH OH,
2
2
NH Me, NH Ph, NH^H^-pMe, py, ( a - p i c o l i n e ) , and a l s o Rh(CO) pyMeC0 ,
2
2
2
[ R h ( C O ) p y ] p h t h a l a t e and [ R h ( C O ) C l ] b i p y .
2
2
2
2
2
I n the l a s t compound bipy i s
functioning as a b i f u n c t i o n a l r a t h e r than a c h e l a t i n g l i g a n d , but v a r i a t i o n
of the proportions of r e a c t a n t s g i v e s some evidence for the formation of
Rh(CO)bipyCl and [ R h ( C O ) b i p y ] C l .
2
These authors
obtained
Hieber's
compound R h ( C O ) p y C l by d i s s o l v i n g RhCCO^Cl'py i n p y r i d i n e , and present
2
2
evidence supporting a 5-co-ordinate diamagnetic monomeric s t r u c t u r e for the
216
complex.
[Rh(CO) X]
2
A l i p h a t i c and aromatic n i t r i l e s r e a c t i n a s i m i l a r manner with
2
(X = C l , B r ) to give Rh(CO> XL, where L = PhCN, p - C l C ^ C N ,
2
2i~i 218
o-.m-or p -MeCH.CN. oc-C. H-.CN. R-C, H_,CN, PhCH CN and p - C l C " CK_CN.
0 4 '
10 7 '
10 7 '
2
6 4 2
218
Two forms of the d e r i v a t i v e s could be i s o l a t e d , designated the a- and B-forms.
0
r
The a-form i s more s t a b l e and i s the simple square-planar complex; the 8-form
-74-
probably i n v o l v e s some metal-metal
i n t e r a c t i o n i n the s o l i d .
Aliphatic
n i t r i l e compounds are much l e s s s t a b l e than the aromatic ones and the CH^CN
and CgH^CN d e r i v a t i v e s could only be i s o l a t e d a t -78°C.
Reaction of
RhCCO^Cl and p-Nl^-CgH^CN gives a monomeric complex with only the amino218
nitrogen co-ordinating to the metal.
Thiocyanate rhodium carbonyl complexes have been prepared
[Rh(CO) SCN] , from AgSCN and [ R h ( C O ) C l ]
2
2
2
2 1 6
,
e.g.
[(n-C H ) N][Rh(CO) (NCS) ],
4
g
4
2
2
and RhL (CO)NCS where L i s a v a r i e t y of phosphine, a r s i n e , s t i b i n e and
219
2
phosphite ligands.
The i o n i c compound was prepared by the a c t i o n of excess
[ ( n - C H ) N ] S C N on [ R h ( C O > C l ]
4
g
4
2
Rh(CO)L Cl and KSCN.
2
2
and the other d e r i v a t i v e s by the r e a c t i o n of
A l l the complexes have metal-nitrogen bonding, as
expected from jt-bonding arguments d i s c u s s e d e a r l i e r , i n the s o l i d s t a t e and i n
solution.
The a r y l a r s i n e and triphenylphosphite d e r i v a t i v e s show a
remarkable
tendency
to form d i n u c l e a r , thiocyanate bridged complexes, the
219
l a t t e r being i s o l a t e d for L = triphenylphosphite:
2Rh(P(OPh) ) (CO)(NCS)
3
2
1
P(OPh) (CO)Rh^
3
Rh(CO)P(OPh> + 2P(OPh>
3
The i r i d i u m carbonyl h a l i d e s a l s o r e a c t r e a d i l y with nitrogen donors to
give simple d e r i v a t i v e s .
[Ir(CO) Cl]
3
n >
which i s polymeric, r e a c t s i n
r e f l u x i n g benzene with p-CH,C,H,NH to give ClIr(CO)„(NH„-C H,p-Me) and
0
r
treatment of t h i s complex with py, o-phen and bipy gives C l I r ( C O ) p y ,
2
3
-75-
C l I r ( C O ) o - p h e n and
2
[ I r ( C 0 ) C l ] b i p y with a l i t t l e
C l I r ( C O ) o - p h e n , and
2
2
2
the b i p y r i d y l a n a l o g u e ,
Ir(CO) Clbipy.
220
In
2
the metal
i s 5-co-ordinate.
221
Angoletta
has a l s o obtained
L = ( p - C H C H N H ) and
3
6
4
2
K [Ir (CO) Br J
2
2
4
t h e c o m p l e x e s I r C c O ^ L X , where X = C l , Br
( C H ^ C H N l ^ , by
w i t h the l i g a n d .
5
treatment
With K [ I r
I I 3 :
of K [ I r ( C O ) C l
2
2
(CO) I ]
4
4
and
4
4
g
]
and
or
p-CH C H NH ,
3
6
4
2
he o b t a i n e d I r ( C O ) _ ( p C H C H N H _ ) „ I _ , w h e r e a s b i p y gave Ir(CO)(bipy)l„,
Z
J O 4 Z Z Z
i.
w h i c h was
o b t a i n e d a s an i s o m e r i c m i x t u r e
o f , p r e s u m a b l y , c i s and
trans
222
modifications.
The r e a c t i o n between K [ I r ( C O ) l , . ] and ammonia, and
- 223
p r i m a r y amines i n t h e c o l d , g i v e s [ I r ( C O ) L I ]
( L = NH^, E t N H and i s o p r o p y l a m i n e ) , when a 1:1 m o l a r r a t i o of r e a c t a n t s i s u s e d .
E x c e s s amine
III
I I
223
gives I r
( C O ) L I i n the c o l d , I r ( C O ) L . j I on warming.
2
4
2
3
2
2
Some rhodium and
i r i d i u m c a r b o n y l d e r i v a t i v e s of some S c h i f f b a s e s
of
224
a c e t y l a c e t o n e h a v e been p r e p a r e d .
These are q u i t e d i f f e r e n t
from
the
183
S c h i f f base
i r o n carbonyl complexes.
The
complexes c o n t a i n a c h e l a t i n g
group w h i c h i s t h e a n i o n d e r i v e d from t h e c o n d e n s a t i o n
amine
with acetylacetone.
[ ( C O ) ( a m i n e ) R h C l ] and
2
and
product
Thus t h e compounds of g e n e r a l
[ ( C O ) ( a m i n e ) l r C l ] were p r e p a r e d
from h a l o g e n o c a r b o n y l i r i d a t e s , and
primary
formula
from
2
of a
[Rh(CO) Cl]
2
2
then r e a c t e d w i t h a c e t y l a c e t o n e .
I n t h e c a s e of i r i d i u m , t h e r e a c t i o n s were n o r m a l l y q u i t e s t r a i g h t f o r w a r d .
/
oe
co
.ci
\
\
Ir
+ C H 0
c
o
>
NH R
2
y
X
CO
> CH + H 0 + H C l
o
&
5
3
&
4
2
'/
\
N
R
R = C H , p-CH C H , a-naphthyl, n-propylamine.
3
o — c
—
^ I r
5 8 2
\
OC
Q
C H
C
\n
3
-76-
When R = isopropylamine, only the N-free dicarbonyl i r i d i u m ( l ) a c e t y l a c e t o n a t e
was obtained.
The r e a c t i o n s of [Rh(CO) (amine)C1] were much more complicated.
2
For example [(CO) (p-CH C H^NH )RhCl] reacted with acetylacetone to give
2
3
6
2
the N-containing c h e l a t e , but a l s o some [ (CO) Rh(C,-H^0 )] and some
2
+
[p-CH C H^NH ] [cis(CO) RhCl ]~.
3
6
3
[(CO) RhCl]
2
2
2
2
S e v e r a l products were i s o l a t e d when
was t r e a t e d with the S c h i f f base 2-p-tolylimino-penten-3-ol-4,
2
[(CO) (p-CH C H^-NH )RhCl] being one of the products.
2
3
6
2
CH
(C0 Rh
2
3
VCH
o
The complexes
with R = C,H , p-CH_C,H., and n-C_H, were
6 5'
3 6 4'
3 7
C
r
N—— C
R
^CH
3
i s o l a t e d as w e l l as the amine complexes R h ( C O ) ( L ) C l , where L = CgH^NH ,
2
2
224
iso-C H NH , 2,6-(CH ) -C H NH , n - C ^ M ^ and p - C H ^ ^ N H ^
3
?
2
3
2
6
3
2
Reaction of [ R h ( C O ) C l ]
2
i n benzene with assymetric c h e l a t i n g l i g a n d s
2
having N and 0 atoms as donors, gave only non-chelated compounds with N
225
atoms as donors.
But i f the r e a c t i o n proceeds i n the presence of BaC0 ,
3
in MeOH, c h e l a t e d dicarbonyl d e r i v a t i v e s a r e obtained:
[Rh(C0) Cl]
9
2
where
2
9
+
N
~l
HO J
M
e
0
B a C
H
)
S
N
(CO) Rh-^ l
0
2
+ HCl
^ o J
n • oo • ax. •<x_.
HO
OH
-77-
Th e analogous i r i d i u m d e r i v a t i v e s , the 8-oxyquinolate, the quinaldinate
and
the a - p y r i d i n e - c a r b o x y l a t e complexes were obtained from
IrCCO^Cp-CH^CgH^Nl^Cl, but the s a l i c y l a l d o x i n a t e was not prepared.
The
i . r . s p e c t r a of the complexes i n the s o l i d a r e much more complex than the
s o l u t i o n spectra.
Metal-metal i n t e r a c t i o n i n the s o l i d i s suggested to
225
account for t h i s , and f o r the dark colours and dichroism of the compounds.
Some i r i d i u m complexes, o r i g i n a l l y thought to be formates, have now been
226
re-formulated as carbonyl d e r i v a t i v e s
and
[IrCl(OAc)(CO) py] «
2
:
IrCl(CO)py ,
2
[IrCl(OAc)(NH )(C0) ].
3
2
The f i r s t compound i s prepared by the a c t i o n of
2
aqueous p y r i d i n e on ( N H ^ ) [ I r C l ^ ( C O ) ] , while the l a s t two r e s u l t from the
226
2
action of NH^ and p y r i d i n e , r e s p e c t i v e l y , on [ I r C l ( C O ) ( O A c ) ] .
2
r e a c t i o n of I r I ( C O )
4
2
2
The
with a l i g a n d , (e.g. 2 , 2 ' - b i p y r i d y l ) and methoxide i o n
gives complexes of the type I r I ( O C O R ) L ( C O ) .
2
2
The c r y s t a l s t r u c t u r e of the
complex diiodocarbonylmethoxycarbonyl(2,2'bipyridyl)iridium ( L
R = Me) has been determined and i s shown i n F i g . I . 1 4 .
CH
I
0,
N
N
Fig.I.14.
2
= bipy,
-78-
6.
N i c k e l , Palladium and
Platinum
Bases co-ordinating through nitrogen atoms normally
cause
disproport-
ionation of Ni(CO)^ to carbonyl-free c a t i o n s and polynuclear carbonyl anions.^
I n a l k a l i n e s o l u t i o n , Ni(CO)^ and p y r i d i n e give,
initially
[ N i ( p y ) g ] [ N i ( C 0 ) g ] but f u r t h e r r e a c t i o n occurs:
2
[ N i ( p y ) ] [ N i ( C O ) ] + 6C0 + 80H
6
2
-
» Ni(OH> + 6HC00" +
6
I n a c i d s o l u t i o n , the [Ni^(CO)gH]
2
anion forms.
2
[Ni^CCOg] "
Ni(CO)^ with amines such as
p y r i d i n e , morpholine and p i p e r i d i n e give [ N i ( B a s e ) ^ ] [ N i ^ ( C O ) g ] .
Careful
study of Ni(CO)^/amine systems, where the amine i s p y r i d i n e , a - p i c o l i n e ,
morpholine and p i p e r i d i n e has shown that NiCcO^L s p e c i e s e x i s t i n s o l u t i o n .
On warming or pumping, [Ni(amine)g][Ni^(CO)g] forms, but the anion disproportionates to Ni and
[FeCo-phen)^]
2+
2— 228
[Ni^(CO)g] ~.
2*4"
Addition of [NiCo-phen)^] ,
or o-phen to the Ni(CO)^/py system gives Ni(CO) (o-phen)
228
2
,
229
which can a l s o be prepared
directly.
Ni(CO)^ and b i p y r i d y l a l s o give
N i ( C O ) b i p y as the primary product, which does not disproportionate, and
2
229
may
be i s o l a t e d .
[Ni(CO) NH ] and
3
3
L i q u i d ammonia and Ni(CO)^ give the
intermediates
[ N i ( C O ) ( N H > ] , both of which disproportionate above
2
3
2
-60°C.^
Tetracarbonyl n i c k e l r e a c t s with dialklcyanamides to give the complexes
230-232
[(R N-CN)Ni(CO) ].
2
2
I n a preliminary note on the complexes the metal
ligand bonding was described as shown i n F i g u r e 1.15 on the b a s i s of i . r .
spectrocopy.
?30
However a more d e t a i l e d i n v e s t i g a t i o n
complexes from the ligands |
N-GsN, (
N-CsN, .
(
\
/
\s=/
CH
3
231
of s e v e r a l
N-CsN , J
1
N-CsN
v_/
-79-
and
^j^N-GsN suggested
that the -CsN was i n f a c t l o c a l i s e d , and the
s t r u c t u r e was as shown i n F i g . I . 1 6 .
R
\
R = CH„
R
/
,co.
5sv
Ni:
or
R = (CH -)
-••>*
'CO-
'N
N
/ \
R
R
2
Fig.1.15.
R_N
2
1 \
N
Ni
Ni
1/
N
III
NR
Fig.1.16.
T h i s s t r u c t u r e was based on i . r . , n.m.r. and e l e c t r o n i c s p e c t r a l data, as
231
w e l l as molecular weight and dipole moment measurements.
232
s t r u c t u r e determination of one of these complexes
A crystal
, carbonyl(piperidine-N-
c a r b o n i t r i ! e ) n i c k e l has shown that n e i t h e r of the above d e s c r i p t i o n s i s
correct.
and
The s t r u c t u r e 1.17 contains
to a cyanonitrogen group.
trimers of n i c k e l atoms o^-bonded to CO
There a r e no >N=C=NR_ groups as these would
-80-
o
O
v
*/•
N
Ni
CO
O
Fig.I.17.
be l i n e a r and perpendicular to the l i n e Ni-Ni.
The trimer i s formed from the
monomer by using the it-bonds of the cyano groups.
The bond d i s t a n c e s a r e i n
accord with -NsC-NR^ groups and the N and C atoms of the cyano-groups are
e q u i d i s t a n t from the n-bonded Ni.
The N atom of the p i p e r i d i n e r i n g i s not
232
involved i n bonding to Ni.
The simple carbonyls, M(C0)^
5
of palladium and platinum are not known,
but carbonyl h a l i d e s and some base s u b s t i t u t e d compounds have been prepared
An aqueous s o l u t i o n of PdClg and an excess of o-phenanthroline r e a c t with a i r
and CO to give a s t a b l e red complex, formulated as
[(o-phen)Pd(CO) Pd(o-phen).] .4H 0.
2
2
The analogous b i p y r i d y l d e r i v a t i v e i s
233
unstable.
Ammonia complexes e.g. Pt(C0)Cl .2NH
2
3
and P t ( C O ) C l . 2 N H
2
2
3
have been
prepared by passing ammonia i n t o C C l ^ s o l u t i o n s of P t ( C 0 ) C l , P t ( C 0 ) C l
2
2
2
or
-81-
Pt (CO) Cl^.
234
2
2
Solutions of [ P t C l ^ ] ~ anions w i l l r e a c t slowly with CO to
give, probably, [ P t ( C O ) C l ] ~ , and a d d i t i o n of p y r i d i n e to the s o l u t i o n then
3
gives t r a n s - P t ( C O ) p y C l .
The c i s -ammonia d e r i v a t i v e [PtNH^ClCCOjCl] was
2
234
prepared by the a c t i o n of CO on a s o l u t i o n of NH [Pt(NH )Cl.j] .
4
Several bases r e a c t with [ P t ( C O ) X ]
2
3
or [ P t ( C O ) X ] ~ to give the
2
3
complexes trans-Pt(CO)LX , where L = p - t o l u i d i n e
2
235 236
236
'
, aniline
, m-
.,,236
. 234,236
.
... 234,236
,
„, „
nitroamline
, ammonia
'
and p y r i d i n e
'
, and X = C l , Br, I .
v
These d e r i v a t i v e s a r e unstable with r e s p e c t to excess of the l i g a n d , CO
+
being evolved with formation of [ P t ( C O ) L X ] X ~ (when L = NH ) and [ P t L ^ ]
2
236
(when L = NH , p y ) .
3
3
Bidentate l i g a n d s e.g. bipy
+
235236
236
'
, and o-phen
+
_
give [ P t ( C O ) ( L - L ) X ] [ P t ( C O ) X ] " and [ P t ( C O ) ( L - L ) X ] X .
3
237
An i n d i r e c t s y n t h e t i c method
i n v o l v i n g the displacement of a n-
bonded o l e f i n e from a Pt complex by CO, has enabled a large number of
( C O ) P t C l L complexes to be prepared:
2
1
CH
2
C H
S|
CHC1
> Pt *
|
C H
3
L
+ CO
S|
1
CO — P t <
L
I
Cl
+
C.H.
24
Cl
-
Z
or
O . N ^ _ 2
A study of the i . r . and n.m.r. s p e c t r a of the complexes with a v a r i e t y of
s u b s t i t u e n t s i n the p y r i d i n e r i n g (e.g. Z = CH , OCH , N0 , COCH , C0 CH ,
3
3
2
3
2
3
-82-
CH OH, CN, CgH ) has i n d i c a t e d l i t t l e djt-pit* i n t e r a c t i o n between CO and Pt
2
5
237
i n these complexes.
CHAPTER
TWO
Azomethine D e r i v a t i v e s of T r a n s i t i o n Metals
-83-
A.
Introduction
In
t h i s C h a p t e r , s t u d i e s o f a z o m e t h i n e groups i n t r a n s i t i o n m e t a l
s y s t e m s w i l l be d e s c r i b e d .
were s t u d i e d i n i t i a l l y ,
N o n c a r b o n y l c o b a l t ( l l ) and n i c k e l ( l l )
and t h e work was t h e n e x t e n d e d t o c o b a l t
systems
carbonyl
compounds.
Imino-compounds were c h o s e n a s l i g a n d s s i n c e , i n p r i n c i p l e , they c a n
bond i n a v a r i e t y o f ways t o a t r a n s i t i o n m e t a l .
d e r i v a t i v e would c o n t a i n
the n i t r o g e n
The s i m p l e s t t y p e o f
t h e n e u t r a l l i g a n d R2C=NH o-bonded t o t h e m e t a l v i a
lone p a i r , but s i n c e the nitrogen
i s p a r t o f an u n s a t u r a t e d
s y s t e m , n-bonding v i a b a c k - d o n a t i o n o f e l e c t r o n s from f i l l e d m e t a l
i n t o j r - a n t i b o n d i n g o r b i t a l s o f the ^C=N- bond i s p o s s i b l e .
ligand,
As a n a n i o n i c
t h e i m i n o - g r o u p would f o r m a l l y be a 1- o r 3 - e l e c t r o n donor, b u t
stabilisation
bridge
d-orbitals
t h r o u g h it-backbonding i s s t i l l
two m e t a l atoms.
possible; the ligand could
A t h i r d b o n d i n g p o s s i b i l i t y would be l a t e r a l
also
co-
o r d i n a t i o n o f t h e C=N- group t o form a it-complex a n a l o g o u s t o d e f i n e
complexes.
carbonyl
T h e C-N s t r e t c h i n g f r e q u e n c i e s
a n d , where a p p r o p r i a t e , t h e
s t r e t c h i n g f r e q u e n c i e s , were e x p e c t e d t o be s e n s i t i v e
t o t h e mode
of a t t a c h m e n t o f t h e k e t i m i n e group to t h e m e t a l and i t was hoped t o s t u d y
the b o n d i n g by i n f r a r e d s p e c t r o s c o p y .
For
a n e u t r a l l i g a n d , t h e most l i k e l y g e o m e t r i c a l
r e l e v a n t atoms i s shown i n F i g . I I . 1, t o g e t h e r
with
arrangement of the
jr'-orbitals
involved i n
2
back-donation.
p
and p
The t r i g o n a l n i t r o g e n
atomic o r b i t a l s
(relative
atom i s sp
hybridised, involving the
t o t h e a x e s shown), w h i l e
the p
orbitals
-84-
on n i t r o g e n
orbitals.
and
The
carbon overlap
d^
o r b i t a l on
z
to form the n-bonding and
the m e t a l would be
-antibonding
of c o r r e c t
symmetry to
over-
l a p w i t h t h e n* o r b i t a l s .
If
the i m i n o - g r o u p i s a n i o n i c ,
t h e n s e v e r a l bonding modes a r e
possible.
2
Firstly,
i n one
extreme the n i t r o g e n
lone p a i r could
occupy t h e
sp
x
>y
23 8
orbital
shown bonding the h y d r o g e n i n F i g . I I . 1 .
the l o n e p a i r i n an
sp-hydrid
jt-bonding, a s he h a s
r e s u l t s has
pair
o r b i t a l may
c a l c u l a t e d overlap
t h i s were the c a s e ,
electron
on
the
in Fig.II.2.
be
O v e r l a p of f i l l e d m e t a l
the a n i o n i c
above, i s a l s o
m e t a l d - o r b i t a l s , and
skeleton
overlap
also
occur.
Of
relevance
h e r e i s the b o n d i n g of an
u.v.
spectra
show t h a t ( a ) the C-N-Si s k e l e t o n
bond c h a r a c t e r
more
T h i s a r r a n g e m e n t m a x i m i s e s the p o s s i b i l i t y of
can
The
If
d-orbitals
l i g a n d , a l i n e a r M-N-C
l o n e p a i r , i n a p u r e p^ o r b i t a l , w i t h s u i t a b l e m e t a l
element, s i l i c o n .
lone
possible.
nitrogen
applied
his
system.
regarded as c o n t r i b u t i n g
ligand described
l a p between l i g a n d i t * - o r b i t a l s and
multiple
,
to L — > M
the b a s i s of
i s possible, i n a non-linear
to the L-M b o n d i n g .
s e c o n d extreme f o r
illustrated
significantly
i n t e g r a l s and
then the l i g a n d c o u l d
w i t h the jt* o r b i t a l s of
The
contribute
to E b s w o r t h
a g r e e d t h a t s u b s t a n t i a l ( s p — > d ) it-bonding form a n i t r o g e n
to empty s i l i c o n d - o r b i t a l s
than one
According
over-
the
d-orbitals
i m i n o group to t h e m a i n group
of i m i n o s i l a n e s have been i n t e r p r e t e d
i s b e n t and
239
i n the Si-N
of
is
link.
to t r a n s i t i o n m e t a l s , where the
(b) that
there
i s very
I f these
r e s u l t s can
d - o r b i t a l s are at l e a s t
to
little
be
partially
bo
<U
bo
60
0)
cd
cd
00
0)
Hi
>4-(
01
en
CM
bO
bO
PL,
f±4
4-<
cd
Li
cd
cu
cu
cu
CO
<u
-85-
filled,
at
t h e y would i m p l y an a n g u l a r a r r a n g e m e n t b a s e d on
the n i t r o g e n
atom, and
to a s e c o n d m e t a l atom.
t h a t the l o n e p a i r c o u l d
r e s u l t i n g i n a weakening of
the C=N
(C=N) rt* o r b i t a l s c o u l d
bond.
This
lower than i n the
s h o u l d be
free
I f a c o m p a r i s o n c a n be made between n e u t r a l
d e r i v a t i v e s , and
unsaturated
c o m p l e x e s of o t h e r l i g a n d s
system (e.g.
dn-n* i n t e r a c t i o n i n t h e
of e.g.
pyridine
and
occur,
reflected in a
than that
found i n a
imino-transition metal
nitrogen
in
an
b i p y r i d y l d e r i v a t i v e s ) , the amount
p r o b a b l y be
small.
p y r i d i n e metal c a r b o n y l complexes have suggested t h a t
and
of
ligand.
containing
imino d e r i v a t i v e s w i l l
a c t i o n i s sometimes n o n - e x i s t e n t ,
donation
complex, o v e r l a p
i n t h e C=N v i b r a t i o n a l f r e q u e n c y to a l o w e r v a l u e
mononuclear d e r i v a t i v e , and
hybridisation
available for
I n a ligand bridged dinuclear
d - o r b i t a l s on b o t h m e t a l atoms w i t h the
shift
be
sp ~
i n other cases
19
e x t e n t . (p.^9).0f the c o m p l e x e s c o n t a i n i n g
anionic
this
Studies
inter-
o c c u r s o n l y to a
ligands
discussed
of
small
in
1 QC
Chapter I , the
i r o n compound [ ( ( C H C H ^ = N ) F e ( C O ) ]
3
6
3
2
, I . l l f .(p.60) i s o f
2
p a r t i c u l a r relevance
nitrogen
any
and
the
I t s s t r u c t u r e i s c o n s i s t e n t w i t h sp
o
s h o r t Fe-N
other reported
character
here.
bond d i s t a n c e
iron carbonyl nitrogen
i n the Fe-N
U n f o r t u n a t e l y , the C-N
bond of
the
complex, i m p l i e s
type implied
s t r e t c h i n g f r e q u e n c y was
d i s c u s s i o n of
the bonding from t h i s p o i n t
the
and
existence
( a v e r a g e 1*94 A ) ,
s t r u c t u r e of
bonding p r e s e n t e d above.
The
hybridised
shorter
than i n
some d o u b l e bond
i n the above d e s c r i p t i o n .
not
reported,
of v i e w i s n o t
so
further
possible.
t h i s complex s u p p o r t some of
the
However,
ideas
complex [ ( P h C = N - N ) ( F e ( C 0 ) ) . J , 1.11c.
9
9
1
on
182
ir-
-86-
is
a l s o noteworthy, a s i t c o n t a i n s
shows ( t o g e t h e r w i t h o t h e r
two t r i p l y - b r i d g i n g n i t r o g e n atoms, and
examples) that nitrogen i s capable
of co-
o r d i n a t i o n t o p o l y n u c l e a r m e t a l s y s t e m s i n ways a t l e a s t a s v a r i e d a s
carbon.
A r y l k e t i m i n e s were u s e d a s s t a r t i n g m a t e r i a l s a s t h e y a r e s t a b l e to
r e - a r r a n g e m e n t , have been s t u d i e d q u i t e e x t e n s i v e l y and c a n be r e a d i l y
prepared.
A l k y l k e t i m i n e s would have p r o v i d e d
more s t r u c t u r a l d a t a
from
n.m.r. s t u d i e s , b u t t h e y c o u l d n o t be s u c c e s s f u l l y s y n t h e s i s e d i n t h e s e
240
laboratories.
The p r e p a r a t i o n o f a l k y l k e t i m i n e s h a s been r e p o r t e d by t h e
241
242
addition of Grignards
or alkylaluminium
compounds t o t h e c o r r e s p o n d i n g
nitriles
and s u b s e q u e n t h y d r o l y s i s o f t h e p r o d u c t .
s y n t h e s i s i s probably
The d i f f i c u l t y i n t h e i r
due t o t h e hydrogen i n t h e c c - p o s i t i o n i n t h e k e t i m i n e ,
243
w h i c h e n t e r s i n t o enamine t a u t o m e r i s m
silanes
239
, a s h a s been o b s e r v e d
f o r imino-
.
; i.e.
C=N-SiMe
3
n
/
CH
<
•
C-N(H)SiMe.
^
3
CH
2
ketimine
enamine
T h i s l a b i l e h y d r o g e n i s a c i d i c , and l i b e r a t i o n o f a l k a n e
from G r i g n a r d s o r
244
alkylaluminium
compounds h a s been o b s e r v e d
responsible f o r the d i f f i c u l t y
, and t h i s
f a c t o r i s probably
i n obtaining alkylketimines.
Arylketimines
240
are r e a d i l y prepared
from b e n z o n i t r i l e , by t h e G r i g n a r d
route.
-87-
M e t a t h e t i c a l r e a c t i o n s u s i n g P h C = N L i and
2
h a l i d e complex h a v e been s t u d i e d i n a t t e m p t s
i n t o metal
systems.
i n Ph C=N-N=CPh
2
2
by
t h e r m a l or p h o t o c h e m i c a l
3
with a metal
to i n t r o d u c e k e t i m i n o g r o u p s
s i n g l e bond
i n i t i a t i o n i n the presence
of
attempted.
N o n c a r b o n y l c o b a l t c o m p l e x e s and
1.
2
I n a d d i t i o n , h e m o l y t i c c l e a v a g e o f the N-N
d i c o b a l t o c t a c a r b o n y l , was
B.
Ph C=NSiMe
ketimines
Experimental
(a)
2Ph,,C=NLi + a n h y d r o u s C o C l
2
A s o l u t i o n o f d i p h e n y l k e t i m i n o l i t h i u m . ( 1 5 * 2 mmoles) i n e t h e r ( 4 0
was
prepared
as f o l l o w s .
i n e t h e r i n one
arm
of a
A s o l u t i o n of d i p h e n y l k e t i m i n e ( 2 * 7 5 g.,
double Schlenk
e q u i m o l a r q u a n t i t y of n - b u t y l l i t h i u m
t u b e , was
i n hexane was
2*60
ml.)
ml.)
f r o z e n t o -196°C and
an
added by s y r i n g e .
245
(Methyl
The
lithium
i n e t h e r may
r e d m i x t u r e was
allowed
a l s o be u s e d
t o warm up
1 h r . to e n s u r e c o m p l e t e r e a c t i o n .
mmoles) was
to b l a c k was
to room t e m p e r a t u r e
for
Anhydrous c o b a l t c h l o r i d e ( l ' O g.,
7'6
observed.
added by
An immediate d a r k e n i n g
A f t e r overnight s t i r r i n g
under vacuum, l e a v i n g a g r e y - b l a c k gum.
m i s c i b l e with petroleum
and
and
available).
stirred
s l u r r i e d w i t h e t h e r (25 ml.)
red ketiminolithium solution.
, but i s l e s s r e a d i l y
s y r i n g e to t h e
blood-
i n c o l o u r through
the s o l v e n t was
A l t h o u g h t h e gum
was
brown
removed
slightly
e t h e r (80-100°) and more so w i t h t o l u e n e , e f f o r t s
to
obtain a s o l i d r e s u l t e d only i n a black t a r .
A d d i t i o n of t r i p h e n y l p h o s p h i n e
resulted
to a t o l u e n e s o l u t i o n of t h e gum
i n i s o l a t i o n of a b l a c k t a r , w h i c h t u r n e d g r e e n y - y e l l o w
on
still
exposure
-88-
to a i r .
When t h e r e a c t i o n was
r e p e a t e d by a d d i n g
a THF
s o l u t i o n of C o C l
2
t h e P h C = N L i s o l u t i o n c o o l e d t o -196°C,and a l l o w i n g t h e m i x t u r e
t o warm up
s l o w l y , the b l a c k c o l o u r developed
but
2
no p r o d u c t
c o u l d be
w e l l b e l o w room t e m p e r a t u r e ,
2
L
3
2
2
A s o l u t i o n of d i p h e n y l k e t i m i n o l i t h i u m
prepared
a s above.
2*1 mmoles) was
mixture
allowed
The
2
to warm to room t e m p e r a t u r e ,
t h e s o l v e n t was
b l u e and w h i t e
t o g i v e a deep b l u e s o l u t i o n w h i c h
P h C = N L i s o l u t i o n was
b l u e p r e c i p i t a t e were o b s e r v e d .
temperature,
solids.
( 4 mmoles) i n e t h e r ( 2 0
B i s ( t r i p h e n y l p h o s p h i n e ) c o b a l t d i c h l o r i d e (1*4
d i s s o l v e d i n THF
c o o l e d to -196°C.
again
isolated.
(b) 2Ph C^NLi jMPh P) CoCl
was
to
added by
ml.)
g.,
was
s y r i n g e , and
the
when a b l u e s o l u t i o n and much
After stirring
f o r 30 min. a t room
removed under vacuum, l e a v i n g a m i x t u r e
Washing w i t h p e t r o l e u m
e t h e r ( 4 x 10 m l . )
of
and
e v a p o r a t i o n o f t h e w a s h i n g s gave w h i t e c r y s t a l s o f t r i p h e n y l p h o s p h i n e , w h i c h
were i d e n t i f i e d by
the i n f r a r e d
t h e m e l t i n g p o i n t (77°C, lit.80°C) and by c o m p a r i s o n of
spectrum
w i t h t h a t o f an a u t h e n t i c sample.
The b l u e s o l i d r e m a i n i n g
e x t r a c t i o n w i t h tnot b e n z e n e .
were washed w i t h p e t r o l e u m
was
r e c r y s t a l l i s e d by
continuous
A f t e r c o o l i n g to room t e m p e r a t u r e ,
e t h e r and
pumped d r y .
The
compound
c h a r a c t e r i s e d as b i s ( d i p h e n y l k e t i m i n e ) c o b a l t d i c h l o r i d e ,
M.Pt.
14*4%.
238-242°C
CoC
9 f i
Y i e l d , 0 = 72 g.
H, N Cl
9
9
9
(72%).
liquid
the
crystals
was
(Ph C=NH) CoCl .
2
2
2
Found: C.63-4; H,4-3; N.5-6; C I ,
r e q u i r e s C,63'4; H,4«5; N,5*7; C l , 1 4 ' 4 % .
The
infrared
-89-
s p e c t r u m showed t h a t h y d r o g e n h a s
confirmed the a b s e n c e of
CoCl
2
Anhydrous c o b a l t
cobalt
i n t o a THF
yellow solution slowly
b l u e s o l i d had
s o l i d was
liquid
( 1 * 6 g.,
t o g e t h e r by
s o l u t i o n of
became b l u e ,
and
M.Pt. 237-241°C.
diphenylketimine
continuous l i q u i d
The
extraction
initially
of
pale
a f t e r o v e r n i g h t e x t r a c t i o n , much
cooling
to room t e m p e r a t u r e , t h e
recrystallised
e x t r a c t i o n , washed w i t h p e n t a n e and
d i c h l o r i d e was
12 mmoles) and
the k e t i m i n e .
and
After
filtration
phenylketimine)cobalt
(b).
chloride
precipitated.
i s o l a t e d by
and
2
25 mmoles) were r e a c t e d
chloride
to the n i t r o g e n ,
triphenylphosphine.
( c ) 2Ph C=NH +
( 5 ml.,
become a t t a c h e d
from benzene by
pumped d r y .
identical
to
the
The
blue
continuous
complex, b i s ( d i -
sample p r e p a r e d
Found: C,63'6; H,4'5; N,5'7; C l , 1 5 ' 0 % .
CoC
in
2 6
H
2 2
N Cl
2
2
r e q u i r e s C,63'4; H,4'5; N,5*7; C I , 1 4 ' 4 % .
( d ) . ( i ) 2Ph C=N-SiMe
2
3
+
(P^P^CoCl,,
B i s ( t r i p h e n y l p h o s p h i n e ) c o b a l t d i c h l o r i d e ( 1 * 3 g.,
dissolved
i n THF
(45 ml.)
k e t i m i n e ( 0 * 9 5 ml.,
o b s e r v e d , and
oil
(80-100°) and
T h i s compound was
p e n t a n e , and
On
cooling
( I ) p r e c i p i t a t e d w h i c h was
was
the
the
was
N-(trimethylsilyl)diphenyl-
(5 ml.)
a f t e r overnight s t i r r i n g ,
b a t h 90-100°C).
solid
a s o l u t i o n of
4 mmoles) i n THF
l e a v i n g a blue s o l i d .
ether
and
2 mmoles)
was
added
solvent
appreciably
extracted
filtered
c o l l e c t e d by
was
No
change
removed under vacuum,
soluble
w i t h hot
was
i n petroleum
toluene (50
s o l u t i o n i n an
ml.,
i c e bath, a
f i l t r a t i o n , washed w i t h p e n t a n e
-90-
and pumped d r y .
M.Pt.
182-4°C
Found: C,64«8; 65*4; 65'57„.
H,
(Ph C=NH)(Ph P)CoCl
2
3
bands due
2
r e q u i r e s C,64'6; H,4'5.
3*8;
The
5-17..
infrared
spectrum
to b o t h t r i p h e n y l p h o s p h i n e and d i p h e n y l k e t i m i n e , and
as (Ph P)(Ph C=NH)CoCl .
3
2
The
3*6;
F u r t h e r comment i s d e f e r r e d u n t i l
2
b l u e t o l u e n e mother l i q u o r r e m a i n i n g
after
I i s formulated
the n e x t
f o r 2 days, deposited blue c r y s t a l s ,
almost
On
The
crystals
I,
M.Pt.
228°C.
temperature,
The
( P h . j P ) ( P h C = N H ) C o C l , and
2
occurred.
2
f o r 24 h r s . ) were u n s u c c e s s f u l .
i n f r a r e d spectrum
The
s o l u t i o n and
r e a c t i o n was
T h i s was
identical
197-199°C
3
+
(Ph P) CoCl
3
2
after
filtration
identified
as
Found: C,64«8; H,4'7; N,2«5; Cl,12«5%.
0
presence of c o - o r d i n a t e d
the n i t r o g e n .
The
had
2.
washed r a p i d l y w i t h p e n t a n e and
to I above, and was
of
2
r e p e a t e d a s above, and
r e q u i r e s C,64*6; H,4'5; N,2*4; Cl,12'47 .
h y d r o g e n on
from t h a t
e v a p o r a t i o n to s m a l l b u l k , c o o l i n g to -78°C c a u s e d
of a b l u e s o l i d .
compound was
e t h e r (80-100°) and
of I I d i f f e r e d
T h i s complex i s a l s o d e s c r i b e d i n s e c t i o n
2
the
to r e d i s s o l v e t h e c r y s t a l s i n
showed t h a t l o s s of t r i p h e n y l p h o s p h i n e
( d ) . ( i i ) 2Ph C=NSiMe
M.Pt.
attempts
( I I ) were i s o l a t e d , washed w i t h p e t r o l e u m
pumped d r y .
l e a v i n g an
washing these c r y s t a l s w i t h pentane,
w a s h i n g s r e m a i n e d c o l o u r l e s s , and
t o l u e n e ( a t 90-100° o i l b a t h
section.
s e p a r a t i o n of I , a f t e r
s t a n d i n g a t room t e m p e r a t u r e
colourless solution.
showed
infrared
t r i p h e n y l p h o s p h i n e and
of the
THF
crystallisation
pumped d r y .
This
(Ph P)(Ph C=NH)CoCl .
3
CoC
2
3 1
spectrum
H
2 2
NPCl
2
2
confirmed
d i p h e n y l k e t i m i n e , and
also
the
-91-
P r o l o n g e d s t a n d i n g a t room t e m p e r a t u r e
o f t h e THF mother l i q u o r
caused
d e p o s i t i o n o f b l u e c r y s t a l s , w h i c h were i s o l a t e d , washed w i t h p e n t a n e and
pumped d r y .
The i n f r a r e d
spectrum
o f t h e s e c r y s t a l s was i d e n t i c a l
of I I and showed l o s s o f PPh.j h a d o c c u r r e d .
formulated a s [ ( P h C = N H ) C o C l l .
2
2
T h i s complex i s t e n t a t i v e l y
M.Pt. 212°C.
2
to that
Found: C,55'3; H, 3-4; C l ,
25*8%
C.53-3; H,4-5; C l , 2 1 - 9 % .
C
C
H
N
°2 26 22 2
C 1
4
r
e
{
l
u
i
r
e
s
C,50'2; H,3'5; C l , 2 2 ' 8 % .
Evaporation o f the almost
gummy s o l i d , whose i n f r a r e d
probably
c o l o u r l e s s THF mother l i q u o r gave a g r e y ,
spectrum
indicated
t h e p r e s e n c e o f PPh^ and
Ph C=N-SiMe .
2
3
L o s s o f t r i p h e n y l p h o s p h i n e from I , ( P h . j P ) ( P h C = N H ) C o C l , was a c h i e v e d
2
by h e a t i n g a l i t t l e
temperature).
identical
o f I i n t o l u e n e f o r 3 d a y s , a t 90-100°C ( o i l b a t h
The b l u e c r y s t a l s w h i c h s e p a r a t e d o u t h a d an i n f r a r e d
to that o f I I .
g a v e a gummy w h i t e
PPh^ and p r o b a b l y
Evaporation of the almost
s o l i d whose i n f r a r e d
spectrum
colourless
indicated
spectrum
toluene
solution
the presence of
benzophenone.
Attempted s u b l i m a t i o n o f ( P h P ) ( P h C = N H ) C o C l
3
produced a s m a l l amount o f w h i t e
benzophenone, a s d e t e r m i n e d
toluene u n t i l
2
2
by i n f r a r e d .
r e c o v e r e d from t h e t o l u e n e e x t r a c t s .
m a t e r i a l remaining had an i n f r a r e d
grey during h e a t i n g .
a t 70°C o v e r 2 weeks,
s o l i d , w h i c h c o n s i s t e d o f PPh^ and p r o b a b l y
The b l u e r e s i d u e was e x t r a c t e d w i t h
t h e w a s h i n g s were c o l o u r l e s s .
t h i s compound, I I I ,
2
( P h P ) ( P h C = N H ) C o C l was
3
2
2
The s m a l l amount o f t o l u e n e
spectrum
similar
to that of I I .
d i d n o t m e l t below 360°C, a l t h o u g h
Found: C,27'5; H,2*56; C l , 1 9 ' 6 % .
insoluble
However,
the colour paled to
-92-
( e ) 2Ph C=NLi +
Py CoCl
2
2
2
A s o l u t i o n o f d i p h e n y l k e t i m i n o l i t h i u m ( 1 0 mmoles) i n e t h e r ( 5 0 m l . )
was p r e p a r e d
as described i n ( a ) .
B i s ( p y r i d i n e ) c o b a l t d i c h l o r i d e ( 1 * 4 g.,
5 mmoles) was d i s s o l v e d i n THF ( 1 0 0 m l . ) and the s o l u t i o n c o o l e d
t o -198°C.
A f t e r a d d i t i o n o f the Ph C=NLi s o l u t i o n , the temperature of the m i x t u r e
2
allowed
to r i s e .
A b l a c k colour developed w h i l e
b e l o w room t e m p e r a t u r e .
t h e t e m p e r a t u r e was
was
still
Removal o f v o l a t i l e s under vacuum gave a b l a c k t a r
w h i c h was m i s c i b l e w i t h e t h e r and t o l u e n e , b u t a t t e m p t s t o i s o l a t e a s o l i d
from t h e s e s o l u t i o n s w e r e u n s u c c e s s f u l .
( f ) 2Ph C=NSiMe
2
(i)
3
+ BipyCoCl
2 , 2 ' - B i p y r i d y l c o b a l t d i c h l o r i d e ( 0 * 4 3 g., 1*5 mmoles) was
p l a c e d i n one arm o f a d o u b l e S c h l e n k
and
2
the suspension heated
overnight
tube, nitrobenzene
a t 100°C ( o i l b a t h
of t h e complex d i s s o l v e d t o g i v e a g r e e n s o l u t i o n .
No r e a c t i o n o c c u r r e d
temperature).
Some
N(trimethylsilyl)di-
p h e n y l k e t i m i n e ( 3 mmoles) was d i l u t e d w i t h n i t r o b e n z e n e
to t h e h o t s u s p e n s i o n .
( 1 0 0 m l . ) was added
( 1 0 m l . ) and added
o v e r 3 days a t t h i s
temperature.
( i i ) 2 , 2 ' - B i p y r i d y l c o b a l t d i c h l o r i d e ( 0 * 8 6 g., 3 mmoles) was
p l a c e d i n a f l a s k and N ( t r i m e t h y l s i l y l ) d i p h e n y l k e t i m i n e ( 1 * 5 m l . , 6 m m o l e s )
was added.
The s o l i d d i s s o l v e d t o some e x t e n t , g i v i n g a b l u e - g r e e n
After stirring
overnight,
a t room t e m p e r a t u r e , t h e n h e a t i n g a t 80-90°C f o r
s e v e r a l d a y s , no change was o b s e r v e d and no new s p e c i e s c o u l d be
(iii)
solution.
detected.
2 , 2 ' - B i p y r i d y l c o b a l t d i c h l o r i d e ( 1 * 7 g., 6 mmoles) and
-93-
N ( t r i m e t h y l s i l y l ) d i p h e n y l k e t i m i n e ( 3 m l . , 12 mmoles) were p l a c e d i n a
walled glass
with
t u b e , w h i c h was
t h e n e v a c u a t e d and s e a l e d .
the temperature b e i n g r a i s e d
i n steps.
The tube was h e a t e d ,
No change was o b s e r v e d u n t i l
t h e t e m p e r a t u r e had r e a c h e d 276°C, when a d a r k e n i n g i n c o l o u r was
1
( B i p y C o C l 2 decomposes a t 268°C, under n i t r o g e n ) ? * ^
room t e m p e r a t u r e and e x t r a c t e d w i t h p e n t a n e .
c o n t a i n b i p y C o C ^ (by i n f r a r e d
O'Ol mm/Hg t o y i e l d
slightly
3
b l a c k s o l i d remained a f t e r d i s t i l l a t i o n
2
3
Removal
shown t o
o f s o l v e n t from t h e
2 ml. of a y e l l o w v i s c o u s l i q u i d .
2
Ph C=NSiMe
The tube was c o o l e d to
w h i c h was d i s t i l l e d
impure P h C = N S i M e , by i n f r a r e d
noticed.
The b l a c k r e s i d u e was
spectroscopy).
p e n t a n e e x t r a c t s gave a d a r k r e d o i l ,
thick
a t 80-110°C,
T h i s was shown t o be
spectroscopy.
A s m a l l amount o f
S i n c e ~*657<, o f
of the o i l .
was r e c o v e r e d , i t was c o n c l u d e d t h a t no r e a c t i o n had
occurred
a p a r t from some d e c o m p o s i t i o n .
2.
R e s u l t s and
Discussion
R e a c t i o n of ( P h P ) C o C l
3
2
w i t h P h C = N L i and Ph C=N-SiMe
2
2
2
b l u e c r y s t a l l i n e complexes ( P h C = N H ) C o C l
2
2
2
and
gave t h e b r i g h t
3
(Ph P)(Ph C=NH)CoCl ,
3
2
2
r e s p e c t i v e l y , w h i c h were i d e n t i f i e d by e l e m e n t a l a n a l y s e s and
spectroscopy.
CoCl
2
(Ph C=NH) CoCl
2
2
2
was a l s o p r e p a r e d d i r e c t l y
from a n h y d r o u s
and Ph C=NH, b u t r e a c t i o n o f P h C = N L i w i t h a n h y d r o u s C o C l
2
2
b l a c k t a r from w h i c h no s o l i d c o u l d be i s o l a t e d , e v e n a f t e r
triphenylphosphine.
(Ph P)(Ph C=NH) CoCl
3
infrared
2
the t e t r a h e d r a l
2
the a d d i t i o n of
The c o l o u r s o f t h e c o m p l e x e s ( P h C = N H ) C o C l
2
gave a
2
2
2
and
1
2
a r e c h a r a c t e r i s t i c o f t e t r a h e d r a l C o * c o m p l e x e s , and
s t r u c t u r e of ( P h C = N H ) C o C l
2
2
2
i s c o n f i r m e d by i t s d i f f u s e
-94-
reflectance
spectrum, recorded
i n t h e r a n g e 25,000 cm ^ t o 10,000 cm *"
-
(400 m/J t o 1,000 m/u), w h i c h shows a b r o a d i n t e n s e band a t 16,000 cm *" w i t h
two
-
s h o u l d e r s a t 16,560 cm"''" and 17,090 cm *.
Tetrahedral c o b a l t ( l l ) halide
c o m p l e x e s o f 2 - c h l o r o p y r i d i n e and 2 - b r o m o p y r i d i n e h a v e s i m i l a r
-1
t h e i n t e n s e band n e a r
On p r o l o n g e d
s t a n d i n g i n t o l u e n e o r THF s o l u t i o n , o r on h e a t i n g i n
3
2
deposited.
247
16,000 cm
toluene, (Ph P)(Ph C=NH)CoCl
are
2
l o s e s PPh
PPh , contaminated
3
3
and b l u e c r y s t a l s o f a complex, ( I I ) ,
w i t h benzophenone, was r e c o v e r e d
t h e THF mother l i q u o r and i d e n t i f i e d by i n f r a r e d
s p e c t r u m o f I I shows t h e a b s e n c e o f P P h
due
to
spectra with
to c o - o r d i n a t e d
Ph C=NH.
3
spectroscopy.
The i n f r a r e d
i n t h e complex, and c o n t a i n s bands
The p o s i t i o n s o f t h e s e bands a r e v e r y
2
from
t h o s e i n t h e s p e c t r u m o f t h e complex ( P h C = N H ) ( P P h ) C o C l .
2
3
2
similar
The b r i g h t
b l u e c o l o u r o f I I i s c h a r a c t e r i s t i c o f t e t r a h e d r a l c o b a l t ( l l ) c o m p l e x e s , and
it
seems l i k e l y
that l o s s of PPh
3
from ( P h C = N H ) ( P P h ) C o C l
2
3
2
h a s caused
d i m e r i s a t i o n and t h e d a t a on complex I I i s c o n s i s t e n t w i t h t h e f o r m u l a t i o n
[(Ph C=NH)CoCl ]2'
2
The i n f r a r e d
2
spectra, particularly
i n d i c a t e t h a t the environment o f the c o - o r d i n a t e d
changed upon d i m e r i s a t i o n , and so I I p r o b a b l y
The
analytical
suggests
data obtained
on I I s u p p o r t s
the presence
diphenylketimine
o f vN-H
i s little
contains chlorine bridges.
the formulation, although i t
t h a t t h e sample i s o l a t e d was s l i g h t l y c o n t a m i n a t e d , p r o b a b l y
with
(Ph.P)(Ph C=NH)CoCl .
0
0
After heating (Ph P)(Ph C=NH)CoCl
3
2
2
i n the s o l i d
state for several
days,
most o f t h e complex was r e c o v e r e d , b u t a l i t t l e b l u e , i n s o l u b l e s o l i d , I I I ,
-95-
remained.
The
i n f r a r e d s p e c t r u m of I I I was
showed t h a t c o m p l e t e l o s s of PPh^ had
d i p h e n y l k e t i m i n e was
still
very similar
a g a i n o c c u r r e d , but
p r e s e n t . ' The
was
shown to be d i f f e r e n t
and
i t d i d n o t m e l t b e l o w 360°C (m.pt. I I , 212°C).
formulated
as a polymeric
that
and
co-ordinated
b l u e c o l o u r of I I I i s a g a i n
c h a r a c t e r i s t i c of t e t r a h e d r a l c o b a l t ( l l ) c o m p l e x e s .
from I I j
to t h a t o f I I ,
i t s carbon
However, complex I I I
c o n t e n t was
considerably
Complex I I I
lower
i s tentatively
compound formed from ( P h P ) ( P h 2 C = N H ) C o C l 2 by
loss
3
of PPh.j and p o s s i b l y some Pti2C=NH.
Polymeric
structures with chlorine
b r i d g e s a r e known f o r o t h e r c o b a l t c h l o r i d e c o m p l e x e s , f o r example a n h y d r o u s
248
C0CI2
and
the v i o l e t
form of P y 2 C o C l 2 , i n w h i c h t h e c o b a l t i s i n an
249
o c t a h e d r a l environment.
(Py2CoCl2 a l s o e x i s t s i n a l e s s s t a b l e blue
249
monomeric, t e t r a h e d r a l form w h i c h c o n v e r t s t o t h e v i o l e t
form on s t a n d i n g ) .
R e a c t i o n o f ( p y ^ C o C l g w i t h Ph2C=NLi a t room t e m p e r a t u r e
tar;
the s m e l l of f r e e p y r i d i n e was
solid
( p y ^ C o C l j does n o t b e g i n
t a r produced resembled
and
a g a i n no
detected during
the r e a c t i o n , although
to l o s e p y r i d i n e u n t i l
that obtained
s o l i d c o u l d be i s o l a t e d .
102°C.^^
The
(Ph_P)(Ph C=NH)CoCl
of ( P h j P ^ C o C ^ and
black
Using
( b i p y ) C o C l 2 and Ph2C=NLi,
CoC^,
no
occurred;
t o decompose a t 268°C, under n i t r o g e n .
a b s o r p t i o n s i n the i n f r a r e d
0
The
i n t h e r e a c t i o n of Pb.2C=NLi w i t h
r e a c t i o n c o u l d be d e t e c t e d b e l o w 276°C, when d e c o m p o s i t i o n
(Bipy)CoCl2 begins
gave a b l a c k
0
are l i s t e d
s p e c t r a of (Ph2C=NH)2CoCl2
i n T a b l e I I . 1 , w h i c h a l s o i n c l u d e s the s p e c t r a
Ph2C=NH f o r c o m p a r i s o n .
The
s p e c t r a o f the two
compounds d e r i v e d from ( P h P ) ( P h C = N H ) C o C l 2 were i d e n t i c a l
3
and
2
polymeric
to t h a t of
-96-
Table I I . 1 .
Infrared Spectra of tetrahedral C o
11
Ph_C=NH (liquid
complexes (Nujol mull) and of
smear)
Ph P
-CoCl
2
(Ph C=NH) CoCl
2
2
2
Ph C=NH
2
(Ph P) CoCl
3
2
2
Ph C=NH-^^'
2
-1
-1
cm
cm
3279(vw)
1600(s)
1567(s)
1479(sh)
1451(sh)
1437(s)
1393(sh)
1238(m)
1186(w)
1161(w)
1126(vw)
1099(s)
1075(w)
1029(m)
1000(m)
973(w)
939(w)
911(w)
868(s)
791(s)
763(s)
745(vs)
740(sh)
-1
cm
3279(w)
1597(s)
1567(s)
3257(w)
1603(m)
1572(m)
1451(sh)
1449(m)
1395(sh)
1236(ms)
1364(s)
-1
cm
1435(s)
1163(w)
1196(ms)
1179(sh)
1149(w)
I075(w)
1030(w)
1000(w)
I072(w)
1029(w)
1000(vw)
939(m)
910(m)
868(s)
852(sh)
791(s)
763(s)
1181(w)
1156(w)
I096(s)
I068(vw)
1026(w)
997(w)
927(m)
891(s)
787(s)
761(s)
746(vs)
740(sh)
719(w)
/ \}y
i
a
704 J s p l i t
693(vs)
643(s)
617(w)
521(vs)
499(vs)
708 "]vs
704 J s p l i t
695(s)
643(s)
616(vw)
709(ms)
696(vs)
623(s)
692(vs)
520(vs)
497(vs)
-97-
(Ph C=NH) CoCl 2
2
2
The
vN-H
and
vC=N s t r e t c h i n g
f r e q u e n c i e s of
several
d i p h e n y l k e t i m i n e c o m p l e x e s of t r a n s i t i o n m e t a l s a r e shown i n T a b l e I I . 2 ,
comparison.
behaviour
I t c a n r e a d i l y be
s e e n t h a t t h e r e i s no d i s t i n c t
of e i t h e r parameter.
The
c o b a l t complexes, i n ( P h C = N H ) C u C l
2
2
shift
2
and
to h i g h e r f r e q u e n c y
for
trend i n
of vN-H
i n the
i n t h e molybdenum c a r b o n y l complex
253
i s a l s o observed
i n diphenylketimine adducts
of main group m e t a l s .
the manganese c a r b o n y l h a l i d e d e r i v a t i v e s , t h e s h i f t
o f vN-H
i s c o n s i s t e n t with electron withdrawal
upon c o - o r d i n a t i o n .
vC=N seems t o be l i t t l e
t h e l i g a n d , a s h a s been o b s e r v e d
to l o w e r
a f f e c t e d by c o - o r d i n a t i o n o f
253
f o r m a i n group m e t a l
2
Direct
source a t temperatures
peak a t M/e
No
181
2
o f 95°C, 160°C and
+
fragments
2
2
due
and
(Ph P)(Ph C=NH)CoCl ,
3
3
+
and
2
2
the
t o breakdown of t h i s i o n .
Similarly,
obtained w i t h a source temperature
peaks c h a r a c t e r i s t i c of [ P h P ]
The
2
200°C gave s p e c t r a showing a p a r e n t
c o b a l t - c o n t a i n i n g p e a k s c o u l d be d e t e c t e d .
2
complexes.
i n s e r t i o n of t h e former compound, w i t h
( P h C = N H ) and
(Ph.jP)(Ph C=NH)CoCl
frequencies
from n i t r o g e n v i a the cr-bond,
A t t e m p t s to o b t a i n mass s p e c t r a of ( P h C = N H ) C o C l
were u n s u c c e s s f u l .
In
the s p e c t r u m
of 190°C showed
of
only
+
[Ph C=NH] .
2
r e l u c t a n c e of d i p h e n y l k e t i m i n e
t o complex w i t h t r a n s i t i o n m e t a l s
as
an a n i o n i c l i g a n d i s somewhat s u r p r i s i n g , s i n c e m a i n group m e t a l h a l i d e s
254
254
255
(aluminium
, beryllium
and boron
) react r e a d i l y with ketiminolithium
a t room t e m p e r a t u r e to e l i m i n a t e L i X . R e a c t i o n o f Ph_C.=NLi w i t h Mn(CO)^Cl
gave two
c o m p l e x e s , one
o f w h i c h was
formulated
a s Mn(CO) N=CPh
n
2
( n = 4 or 5 ) ,
-98-
Table I I . 2 .
v„
and v_
f o r some T r a n s i t i o n M e t a l
N-H
C=N
D i p h e n y l k e t i m i n e Complexes
Complex
v
Ph C=NH
2
(Ph C=NH) CoCl
2
2
2
(Ph C=NH)(PPh )CdCl
2
3
CuCl .(Ph C=NH)
2
2
2
5
2
0
2
250
CuCl .Ph C=NH
2
N-H
v
(cm )
'
V
C=N
(
c
m
_
1
)
3257
1603
3279
1597
3279
1600
3281
1607
3200
1601
3215
1618, 1597
3215
1616, 1597
3279
1595
2
951
Mn(CO) (Ph C=M) Cl
3
2
2
251
Mn(CO) (Ph C=NH) Br
3
2
2
252
Mo(CO) (Ph C=NH)
3
2
3
-99-
a l t h o u g h Ph C=NSiMe
2
3
w i t h Mn(CO) Br gave o n l y Mh(CO) (Ph C=NH) Br.
5
3
2
251
The
2
source o f the hydrogen i n t r o d u c e d i n t o the l i g a n d i n the f o r m a t i o n o f
k e t i m i n e - c o b a l t complexes from Ph C=NLi and Ph C=NSiMe
2
the s o l v e n t .
2
i s thought
3
t o be
The k e t i m i n e - c o p p e r complexes r e f e r r e d t o i n Table I I . 2 were
prepared by d i r e c t r e a c t i o n o f Ph C=NH w i t h anhydrous C u C l
2
2 >
(Ph C=NH) CuCl
2
2
2
250
being
the major p r o d u c t .
(bipy)CoCl
2
The t e t r a h e d r a l c o b a l t complexes ( p y ) C o C l and
2
were prepared and r e a c t e d w i t h Ph C=NLi and Ph C=NSiMe
2
hope t h a t the n i t r o g e n l i g a n d s a l r e a d y p r e s e n t
2
3
2
i n the
i n t h e complex would
encourage t h e f o r m a t i o n o f a k e t i m i n o d e r i v a t i v e . Lack o f r e a c t i o n between
bipyCoCl
2
and Ph C=NSiMe
2
3
i n d i c a t e s t h a t even when displacement o f t h e
n e u t r a l l i g a n d i n t h e s t a r t i n g m a t e r i a l by Ph C=NH i s made u n f a v o u r a b l e by
2
the presence o f a s t r o n g l y bonding c h e l a t i n g l i g a n d , the a l t e r n a t i v e
r e a c t i o n i e . e l i m i n a t i o n o f Me^SiCl s t i l l w i l l n o t occur
D i f f e r e n c e s i n b e h a v i o u r between Ph C=NLi and Ph C=NSiMe.j have been
2
2
observed w i t h o t h e r m e t a l s .
The Mn(C0),.X system has been mentioned i n t h e
251
p r e c e d i n g paragraph.
I n main group m e t a l systems, Ph C=NLi w i t h
254
aluminium and b e r y l l i u m c h l o r i d e s , d i s p l a c e s a l l the halogens
, whereas
254
2
excess Ph,,C=NSiMe w i l l r e p l a c e o n l y one halogen i n each m e t a l h a l i d e .
3
N e v e r t h e l e s s , i t seems s u p r i s i n g t h a t Ph C=NLi r e a d i l y r e p l a c e s
2
triphenylphosphine
groups i n (Ph.jP) CoCl
2
2
w h i l e g a i n i n g a p r o t o n , whereas
Ph C=NSiMe^ w i l l r e p l a c e o n l y one PPh^ group, a l t h o u g h
2
can s l o w l y l o s e the r e m a i n i n g
both
the r e s u l t i n g complex
Ph^P group and p o l y m e r i s e .
-100-
C.
Non-carbonyl n i c k e l systems
A l t h o u g h L2C8X2 complexes u s u a l l y e x i s t i n a t e t r a h e d r a l
configuration
i n the s o l i d s t a t e , t e t r a h e d r a l s q u a r e p l a n a r and o c t a h e d r a l c o n f i g u r a t i o n s
}
256
are known f o r the n i c k e l complexes L2NiX2«
However, ( P h ^ P ^ N i C ^ has
257
been shown t o have a t e t r a h e d r a l c o n f i g u r a t i o n
and
s t u d i e s o f the r e a c t i o n s
o f t h i s complex w i t h d i p h e n y l k e t i m i n e and i t s t r i m e t h y l s i l y l d e r i v a t i v e were
undertaken.
However, a d d i t i o n o f THF
t o t h e v e r y dark b l u e c r y s t a l s o f
( P h ^ P ^ N i C ^ gave a v i o l e t s o l u t i o n , b u t a l s o a voluminous p a l e - y e l l o w
p r e c i p i t a t e , and
1.
the i n v e s t i g a t i o n o f t h i s r e a c t i o n w i l l be d e s c r i b e d
(Ph P) NiCl
3
2
2
+
THF
B i s ( t r i p h e n y l p h o s p h i n e ) n i c k e l d i c h l o r i d e (4 g., 6 mmoles) was
i n a f l a s k and THF
(30 m l . ) was
added.
The
f o r 30 min. the p r e c i p i t a t e was
occurred only very slowly,
temperature,
the p r e c i p i t a t e .
the b l u e - g r e e n mother l i q u o r was
(10 m l . ) .
over-
t o room
removed by f i l t r a t i o n ,
This
and
was
t w i c e more, and t h e cream c o l o u r e d r e s i d u e f i n a l l y washed w i t h
u n t i l the washings were no l o n g e r green, then pumped d r y .
mother l i q u o r and washings were pumped d r y , and
was
This
refluxed
After cooling
t h e r e s i d u e r e f l u x e d f o r s e v e r a l hours w i t h more THF
repeated
observed.
allowed to s e t t l e .
though, and so the suspension was
n i g h t i n an a t t e m p t t o c o a g u l a t e
placed
s o l v e n t i m m e d i a t e l y became d a r k l y
c o l o u r e d , and r a p i d f o r m a t i o n o f a p a l e y e l l o w p r e c i p i t a t e was
After stirring
first.
washed w i t h pentane (4 x 10 m l . ) .
The
the green s o l i d
THF
combined
remaining
On e v a p o r a t i o n o f t h e pentane washings,
-101-
t r i p h e n y l p h o s p h i n e ( i d e n t i f i e d by i n f r a r e d s p e c t r o s c o p y )
(2 g. , 627„).
recovered
The green s o l i d r e m a i n i n g a f t e r washing w i t h pentane was shown
by i n f r a r e d spectroscopy
The cream
i n the a i r .
was
t o be u n r e a c t e d
(Ph^P^NiC^-
powder i s d e l i q u e s c e n t and g r a d u a l l y t u r n s green on s t a n d i n g
I t s i n f r a r e d spectrum ( N u j o l m u l l ) shove bands a t 1 3 5 0 ( s h ) ,
1261(vw), 1176(w), I 0 5 5 ( s h ) , 1 0 4 2 ( v s ) , 9 1 8 ( s , s h ) , 8 8 5 ( v s ) , 8 0 0 ( v w ) , 722(w),
-1
680(w) c m , which can be a t t r i b u t e d t o c o - o r d i n a t e d THF.
(THF
itself
absorbs a t 1370(vw), 1179(w), 1 0 7 3 ( v s ) , 1 0 3 3 ( s h ) , 9 1 2 ( s ) , 658(w,broad)
cm"^").
A n a l y t i c a l data on t h e compound, i s shown i n Table I I . 3 ,
w i t h t h e o r e t i c a l values
together
f o r NiCl '2THF, NiC^-THF and N i C l .
2
2
Table I I . 3 .
%Ni
%C1
%C
%H
Found
33*5
5*4
31-8, 29-4
23 '4
NiCl .2THF r e q u i r e s
35'0
5*8
25*9
21*5
NiCl^THF
requires
24-3
4*0
35*1
29-2
NiCl
requires
-
-
54 «6
45*4
2
2
Although
n o t c o n c l u s i v e , these f i g u r e s suggest t h e compound i s NiCl '2THF,
2
perhaps c o n t a i n i n g some NiCl .THF.
0
The complex NiCl .2THF has been r e p o r t e d
0
258
p r e v i o u s l y i n the form o f y e l l o w cubes.
d i r e c t r e a c t i o n of N i C l
2
I t c o u l d n o t be prepared
and THF, b u t was o b t a i n e d by replacement o f
ftOIEKOE
" r \
1 8 AUG 1969
lEonoa.,
IBRARj
by
-102-
a c e t o n i t r i l e from a r o y a l b l u e a c e t o n i t r i l e n i c k e l complex.
2.
258 259
'
N i c k e l complexes + k e t i m i n e s
(a) (Ph P) NiCl
3
2
2
+ Ph C=NH
2
B i s ( t r i p h e n y l p h o s p h i n e ) n i c k e l d i c h l o r i d e (1*3 g. , 2 mmoles) was
p l a c e d i n a f l a s k and d i p h e n y l k e t i m i n e (0*7 m l . , 4 mmoles) was added by
syringe.
was
The m i x t u r e was s t i r r e d f o r a few m i n u t e s , and then THF (20 m l . )
added.
The s o l u t i o n immediately
dissolved.
l o o k e d p u r p l e , and a l l t h e s o l i d
A f t e r 30 min. t h e s o l v e n t was removed under vacuum, l e a v i n g a
p u r p l e s o l i d , which was washed w i t h e t h e r and pentane t o remove PPh^.
purple (Ph C=NH) NiCl
2
2
2
was r e c r y s t a l l i s e d r a p i d l y from THF/ether, washed
w i t h e t h e r and pumped d r y .
Yield
0*6 g. ( 6 0 % ) .
Found: C.63'0; H,4«3; N,5*2; Cl,13'77o.
N,5'7; Cl,14*47o.
o f PPh
3
The
M.Pt. 196°C ( d ) .
NiC H N Cl
2 6
2 2
2
2
r e q u i r e s C,63'4; H,4'5;
The i n f r a r e d spectrum ( N u j o l m u l l ) c o n f i r m e d
t h e absence
and showed a b s o r p t i o n s a t t r i b u t a b l e t o Ph C=NH, a t 3 1 9 3 ( s h ) ,
2
3175(m), 1 5 9 7 ( s ) , 1562(m), 1351(w), 1 2 6 6 ( s ) , 1 2 5 2 ( s h ) , 1163(m), I 0 8 7 ( s h ) ,
I 0 7 6 ( w ) , 1031(w), 1002(w), 985(w), 9 4 3 ( s ) , 9 3 7 ( s h ) , 9 1 7 ( s h ) , 9 0 7 ( s ) ,
8 5 5 ( s h ) , 845(w),
7 9 5 ( s ) , 785(m), 7 7 4 ( s h ) , 7 6 9 ( s ) , 726(m), 7 0 7 ( s ) , 6 9 6 ( v s ) ,
6 5 1 ( s ) cm ^.
( b ) NiClp.nTHF + Ph C=NH
2
The
n i c k e l d i c h l o r i d e - T H F adduct (0*38 g., 1*4 mmoles) was p l a c e d
i n a f l a s k and d i p h e n y l k e t i m i n e ( 1 m l . , 6 mmoles) was added.
o c c u r r e d on s t i r r i n g a t room temperature.
and
No r e a c t i o n
A f t e r a d d i t i o n o f THF (15 m l . )
s l i g h t warming, a b l u e - v i o l e t c o l o u r developed i n t h e s o l v e n t and a l i t t l e
-103-
p u r p l e s o l i d was observed.
However, a f t e r s t i r r i n g s e v e r a l hours much
NiCl2'2THF remained, and t h e s o l u t i o n was f i l t e r e d warm.
A mixture of
p u r p l e c r y s t a l s and a cream s o l i d d e p o s i t e d on c o o l i n g , which were i d e n t i f i e d
by i n f r a r e d spectroscopy as (Ph2C=NH)2NiCl2 and NiC^-nTHF, r e s p e c t i v e l y .
The two complexes c o u l d n o t be s e p a r a t e d , as they have s i m i l a r s o l u b i l i t y
properties
and t h e k e t i m i n e complex decomposes s l o w l y i n s o l u t i o n .
(c) (Ph P) NiCl
3
2
2
+ Ph C=NSiMe
2
Bis(triphenylphosphine)nickel
3
d i c h l o r i d e (1*9 g., 3 mmoles) was
t r e a t e d w i t h N ( t r i m e t h y l s i l y l ) d i p h e n y l k e t i m i n e (1*5 m l . , 6 mmoles) i n one
arm o f a double Schlenk
tube.
The dark b l u e - g r e e n m i x t u r e was a l l o w e d t o
s t i r o v e r n i g h t , b u t no change was observed.
Washing w i t h p e t r o l e u m e t h e r
(80-100 ) l e f t a dark green s o l i d and c o m b i n a t i o n o f the washings and
e v a p o r a t i o n y i e l d e d a y e l l o w o i l , shown by i n f r a r e d spectroscopy t o be
Pt^C^NSiMe^.
E x t r a c t i o n o f t h e dark green s o l i d w i t h t o l u e n e gave a brown
v i o l e t s o l u t i o n which y i e l d e d a s m a l l amount o f gummy s o l i d .
The m a j o r i t y
of t h e green s o l i d which was i n s o l u b l e i n t o l u e n e , was shown by i n f r a r e d
s p e c t r o s c o p y t o be u n r e a c t e d
3.
(Ph^P^NiC^.
R e s u l t s and D i s c u s s i o n
When t h e dark b l u e b i s ( t r i p h e n y l p h o s p h i n e ) n i c k e l d i c h l o r i d e complex
was t r e a t e d w i t h THF, displacement o f t h e PPh^ groups o c c u r r e d and t h e
cream s o l i d which p r e c i p i t a t e d c o n s i s t e d o f THF adducts o f N i C ^ , m a i n l y
NiCl .2THF.
9
R e a c t i o n i n t h e absence o f a s o l v e n t between b i s ( t r i p h e n y l -
-104-
p h o s p h i n e ) n i c k e l d i c h l o r i d e and d i p h e n y l k e t i m i n e gave t h e p u r p l e complex
b i d ( d i p h e n y l k e t i m i n e ) n i c k e l d i c h l o r i d e , (Ph C=NH) MG .The two complexes were
2
i d e n t i f i e d by e l e m e n t a l a n a l y s i s
2
l
and i n f r a r e d spectroscopy.
systems NiCl .2THF/Ph C=NH and ( P h P ) N i C l / P h C = N S i M e
2
2
3
only t o a very s l i g h t
2
complexes o f N i *
u
u J-
1
3
reaction
occurred
s t a b i l i t i e s o f o c t a h e d r a l and t e t r a -
1 1
and ( C o ) h a l i d e s w i t h a v a r i e t y o f amines, have
J 247,256,260
been much d i s c u s s e d .
important,
2
extent.
The f a c t o r s g o v e r n i n g t h e r e l a t i v e
hedral
2
However, i n t h e
„
.
.
j
,
•
*
Both s t e r i c and e l e c t r o n i c f a c t o r s a r e
t h e l a t t e r i n c l u d i n g t h e b a s i c i t y o f t h e l i g a n d and i t s j t - a c c e p t o r
p r o p e r t i e s , as w e l l as t h e p o l a r i s a b i l i t y o f the h a l i d e . N i c k e l ( l l ) seems
256
t o show a marked p r e f e r e n c e f o r an o c t a h e d r a l
, r a t h e r than a t e t r a h e d r a l
environment, i n c o n t r a s t t o c o b a l t ( l l ) f o r which t e t r a h e d r a l complexes
256
L C'oX a r e common.
2
The n i c k e l d i c h l o r i d e THF adduct appears from i t s
2
colour
and l a c k o f s o l u b i l i t y i n s o l v e n t s
presumably w i t h c h l o r i n e b r i d g e s ,
The d i f f u s e r e f l e c t a n c e
25,000 cm"
and
1
1
complexes
2 5 6
g i v i n g the n i c k e l an o c t a h e d r a l s t r u c t u r e .
spectrum o f NiCl .2THF, r e c o r d e d over t h e range
2
t o 10,000 cm"
11,900 cm .
o t h e r than THF t o be p o l y m e r i c ,
1
shows bands a t 2 1 , 9 8 0 , ~ 2 1 , 0 5 0 ( s h ) , ~ 1 2 , 9 0 0 ( s h )
Comparison w i t h t h e s p e c t r a o f o t h e r o c t a h e d r a l
( e . g . N i C l : 22,100, ~19,400, 12,900,^11,600 c m
2
- 1
Ni
1 1
and
1
N i p y C l : 2 4 , 1 0 0 , ~ 2 2 , 0 0 0 ( s h ) , 13,900, ~ 1 2 , 5 0 0 ( s h ) cm" ) c o n f i r m s t h a t
2
2
NiCl .2THF has an o c t a h e d r a l c o n f i g u r a t i o n .
0
Bis(triphenylphosphine)nickel
25
d i c h l o r i d e has been shown t o be monomeric, w i t h a t e t r a h e d r a l c o n f i g u r a t i o n ?
Further co-ordination
of ligands
i n t h i s complex i s p r o b a b l y r e s t r i c t e d
by
-105-
the b u l k y PPh^ groups.
257
The
d r i v i n g f o r c e f o r the displacement o f PPh^,
which i s a s t r o n g donor, by the r e l a t i v e l y weak donor THF,
may
be t h a t t h e
r e s u l t i n g compound i s p o l y m e r i c and has n i c k e l i n i t s p r e f e r r e d o c t a h e d r a l
environment.
The
p u r p l e n i c k e l complex (Pb^C™!^!^!^^ i s much l e s s s t a b l e i n m o i s t
a i r than i t s c o b a l t analogue.
I t i s i n s o l u b l e i n hydrocarbon s o l v e n t s ,
e t h e r , carbon t e t r a c h l o r i d e , b u t d i s s o l v e s t o some e x t e n t i n THF
and CHCl^
t o g i v e v i o l e t and b l u e s o l u t i o n s r e s p e c t i v e l y .
solution
causes decomposition
Warming the THF
w i t h p r e c i p i t a t i o n of a white s o l i d .
The
diffuse
r e f l e c t a n c e spectrum o f (Ph2C=NH)2NiCl2 ( r e c o r d e d i n the range 25,000 t o
- 1
10,000 c m ) showed bands a t 19,460, 1 6 , 6 7 0 ( s h ) ,
l l , 9 6 0 ( s h ) —10,000
Comparison w i t h t h e s p e c t r a o f o t h e r o c t a h e d r a l N i
3
I ^ N i ^ C ^ ^ * ' i n d i c a t e s t h a t ( P t ^ C ! ^ ! ^ ! ^ ^ has
Since o t h e r o c t a h e d r a l I ^ N i C ^ complexes e.g.
1 1
complexes o f the
an o c t a h e d r a l
1
cm" .
type
configuration.
N i p y g C ^ have p o l y m e r i c
256
s t r u c t u r e s w i t h c h l o r i n e b r i d g e s i n the s o l i d s t a t e
3
( P t ^ C ! ^ ! ^ ! ^ ^ ^ has
the same s t r u c t u r e .
, i t seems l i k e l y
On d i s s o l u t i o n i n c h l o r o f o r m ,
c h l o r i n e b r i d g e s are b r o k e n , g i v i n g the c h a r a c t e r i s t i c b l u e c o l o u r o f
h e d r a l n i c k e l complexes.
The
3
i n f r a r e d spectrum o f ( P h j C ! ^ ! ^ ! ^ ^
n o t i c e a b l y from t h a t o f (Ph C=NH)2CoCl2•
2
complex i s much s t r o n g e r , and
I n p a r t i c u l a r , vN-H
the o t h e r bands due
that
the
tetra-
differs
i n the n i c k e l
to co-ordinated diphenyl-
k e t i m i n e a r e s h i f t e d by v a r y i n g amounts.
The
r e l u c t a n c e o f the n i c k e l d i c h l o r i d e THF
adduct t o r e a c t w i t h
d i p h e n y l k e t i m i n e r e f l e c t s the s t a b i l i t y o f the complex.
The
almost complete
-106-
l a c k o f r e a c t i o n between ( P h ^ P ^ N i C ^ and Ph C=N-SiMe may
2
3
be due
t o the
absence o f a s o l v e n t t o a c t as a source o f a p r o t o n f o r Pti2C=N , so
the
complex (Ph2C=NH)2NiCl2 can form.
that
The a l t e r n a t i v e r e a c t i o n i . e .
e l i m i n a t i o n o f Me^SiCl (and f o r m a t i o n o f (Pti2C=N)2Ni(PPh.j)2) seems as
u n f a v o u r a b l e as i t was
D.
shown t o be i n the c o b a l t system.
C o b a l t Garbonyls and K e t i m i n e s
1.
Introduction
The work d e s c r i b e d i n t h i s s e c t i o n concerns the e x t e n s i o n o f t h e study o f
d i p h e n y l k e t i m i n e as a n e u t r a l and a n i o n i c l i g a n d i n t o the f i e l d o f m e t a l
c a r b o n y l systems.
C o b a l t c a r b o n y l was
i n v e s t i g a t i o n f o r s e v e r a l reasons.
chosen as t h e c a r b o n y l system f o r
F i r s t l y , t h i s study was p a r t o f a w i d e r
i n v e s t i g a t i o n i n t o the r e a c t i o n s o f i m i n o compounds w i t h t r a n s i t i o n
metal
complexes, e s p e c i a l l y c a r b o n y l complexes, undertaken by t h e r e s e a r c h
group.
251
S e v e r a l o t h e r m e t a l c a r b o n y l systems had a l r e a d y been s t u d i e d
, and
the
background t o these i n v e s t i g a t i o n s w i l l now be b r i e f l y summarised.
The r e a c t i o n o f d i p h e n y l k e t i m i n e w i t h Mn(C0)^X (X = C l , B r ) gave t h e
expected d i s u b s t i t u t e d d e r i v a t i v e s Mn(C0).jL X.
2
The bromide was
also
prepared from Mn(C0),-Br and Ph C=NSiMe.j, a l t h o u g h a complex f o r m u l a t e d as
2
Mn(CO) (N=CPh„) ( n = 4 or 5) was
R e a c t i o n was
o b t a i n e d from Ph„C=NLi and Mn(C0) Br.
c
shown t o occur w i t h h e a t i n g between it-CpFe(C0) X and Ph2C=NY
2
(X = C l , Br; Y = MgBr,
L i or Sa) b u t t h e m i x t u r e o f p r o d u c t s c o u l d noL be
s a t i s f a c t o r i l y separated and i d e n t i f i e d .
between [it-CpMo(C0) ]
3
2
Attempts to i n i t i a t e r e a c t i o n s
and a z i n e s [ (PhC(H)=N-) and (Me C=N-) ] both t h e r m a l l y
2
2
2
-107-
and p h o t o l y t i c a l l y , were u n s u c c e s s f u l and Natir-CpMoCCO)^] w i t h Ph C=NBr gave
2
m a i n l y [ jr-CpMo(C0) ]
3
2
with a l i t t l e
rt-CpMo(C0) Br.
3
However, Ph C=NSiMe
2
r e a c t s w i t h jt-CpMo(C0) Cl t o g i v e t h e d i m e r i c species
3
3
[ jt-CpMo(C0)N=CPh ]
2
2
251
and a l i t t l e monomer, [rt-CpMo(CO) N=CPh ].
2
2
The analogous monomeric
261
t u n g s t e n complex can a l s o be o b t a i n e d i n good y i e l d .
Interestingly,
jt-CpM(CO) Cl r e a c t s w i t h 2 moles o f Ph C=NLi t o g i v e
3
rt-CpM(CO) (Ph CNCPh )
2
2
2
2
where M = Mo^^^, W^^, i n which t h e l i g a n d i s thought t o be bonding as a
p s e u d o - a l l y l i c group.
These two complexes w i l l be discussed
complex [(p-CH -CgH^) C=NFe(CO) ]
3
2
3
2
later.
The
w i t h b r i d g i n g k e t i m i n o groups ( d e s c r i b e d
i n Chapter I ) was o b t a i n e d from t h e c o r r e s p o n d i n g a z i n e and Fe(CO),. b u t t h e
185
c o n d i t i o n s o f t h e r e a c t i o n were n o t s p e c i f i e d .
Another i m p o r t a n t reason f o r i n v e s t i g a t i n g c o b a l t c a r b o n y l - i m i n e systems
stems from t h e w e l l known c a t a l y t i c p r o p e r t i e s o f Co„(C0) .
Q
z
far
This carbonyl,
o
more than any o t h e r , d i s p l a y s remarkable v e r s a t i l i t y i n c a t a l y s i n g
16
numerous o r g a n i c r e a c t i o n s
, including reactions involving
36
and n i t r o g e n - n i t r o g e n u n s a t u r a t e d compounds.
carbon-nitrogen
Many o f these r e a c t i o n s
i n v o l v e c y c l i s a t i o n w i t h i n s e r t i o n o f carbon monoxide, t o g i v e h e t e r o c y c l i c
compounds.
Examples o f t h e f o r m a t i o n o f s u b s t i t u t e d p h t h a l i m i d i n e s
36
S c h i f f bases and a r o m a t i c ketoximes ( a n d a l d o x i m e s )
( i ) and ( i i ) r e s p e c t i v e l y .
from
a r e shown i n e q u a t i o n s
-108-
c»
u
Qr X)
CH
CO
Benzaldehyde a n i l
-
o-i-o
V
N-Ph
Co„(C0)
8
N-phenylphthalimidine
Ph
CO
OH
Co„(C0)
8
Benzophenone amine
5^
3-phenylphthalimidine
The c o b a l t c a r b o n y l c a t a l y s e d r e a c t i o n s a r e a l l t h o u g h t t o proceed v i a i n i t i a l
c o - o r d i n a t i o n o f t h e o r g a n i c compound v i a t h e n i t r o g e n l o n e p a i r , t o
( ^ ( C O j g o r HCo(CO)^.
A p o s s i b l e mechanism f o r a c y c l i s a t i o n r e a c t i o n has
a l r e a d y been g i v e n i n Chapter I ( p . 1 8 ) , and i t was hoped t h a t i s o l a t i o n o f a
k e t i m i n o c o b a l t c a r b o n y l d e r i v a t i v e might l e n d s u p p o r t t o these
ideas.
I n many o r g a n i c syntheses u s i n g c o b a l t c a r b o n y l as c a t a l y s t , a l k y l or
.
.
.
16
a c y i c o b a l t t e t r a c a r b o n y l species a r e thought t o be i n t e r m e d i a t e s .
Perhaps t h e b e s t known r e a c t i o n o f t h i s type i s t h e h y d r o f o r m y l a t i o n , or oxo
r e a c t i o n i n which aldehydes a r e formed from o l e f i n e s , carbon monoxide and
-109-
hydrogen i n the presence o f Co ( C 0 ) :
2.
o
o
.
+ .CO. .
+ .H_
^C=C
/
2
\
C
°2
( C 0 )
— Ic
8 2_>
,
I
100-160°C
I
I
C
100-250 atm.
and
_* C
!
H
0
t h e r e i s some chemical and i n f r a r e d evidence t h a t a c y l c o b a l t
1
c a r b o n y l s a r e formed d u r i n g t h e r e a c t i o n . ^
tetra-
RCo(CO)^ and RCOCo(CO)^ species
have been prepared and i s o l a t e d i n d e p e n d e n t l y , f o r example by t h e a l k y l a t i o n
of t h e c o b a l t h y d r o c a r o n y l a n i o n w i t h a l k a l i h a l i d e s :
C o ( C 0 ) " + RX
4
» RCo(C0) + X"
4
A l k y l d e r i v a t i v e s a r e l o w m e l t i n g a i r - s e n s i t i v e compounds, which a r e u s u a l l y
1
thermally unstable. **
some o r g a n i c
e.g.
RCo(CO)^ and RCOCo(CO)^ species themselves a r e used i n
syntheses.
RX + CO + C o ( C 0 ) "
4
> RC0Co(C0) + X~
4
|R'OH
1
RC00R + HCo(CO).
4
I t was hoped i n t h i s study t o prepare i n t e r m e d i a t e
a l k y l c o b a l t complexes, c o n t a i n i n g a m e t a l - n i t r o g e n ,
compounds s i m i l a r t o
r a t h e r than a m e t a l - c a r b o n
bond.
The p r e p a r a t i o n o f c o b a l t t e t r a c a r b o n y l i o d i d e i n s o l u t i o n had r e c e n t l y
262
appeared i n t h e l i t e r a t u r e
, and i t was thought t h a t t h i s complex might
prove a u s e f u l s t a r t i n g m a t e r i a l f o r t h e s y n t h e s i s
derivative.
o f an a n i o n i c
ketimino
-110-
2.
Experimental
(a) Co (C0)
2
g
+_I
2
+ Ph C=NSiMe
2
3
262
Using the method of Pankowski and Bigorgne
, s o l u t i o n s of d i c o b a l t
o c t a c a r b o n y l (1*3 g., 4 mmoles) and i o d i n e ( 1 g., 4 mmoles) i n cetane ( t o t a l
volume 100 m l . ) were mixed, g i v i n g a deep y e l l o w - b l a c k s o l u t i o n .
The
r e a c t i o n was f o l l o w e d by i n f r a r e d spectroscopy.
A f t e r 2 hrs., absorptions
due t o C o _ ( C 0 ) and i t s thermal decomposition p r o d u c t , Co.(CO),- were
/
o
t\
Li
Q
observed, b u t i n a d d i t i o n , a weak band a t 2115
appeared.
cm"''', assigned
t o CdC0)^I had
Other a b s o r p t i o n s a s s o c i a t e d w i t h t h i s complex a r e i n a r e g i o n
obscured by Co (C0)g a b s o r p t i o n s .
2
The
i n t e n s i t y of t h i s h i g h frequency
d i d n o t i n c r e a s e over a f u r t h e r 2 h r s . , and, s u s p e c t i n g an
band
equilibrium,
N ( t r i m e t h y l s i l y l ) d i p h e n y l k e t i m i n e (2 m l . , 8 mmoles) i n centane (5 m l . )
added.
Gas
disappeared;
e v o l u t i o n was
was
observed and over a p e r i o d o f 73 h r s . , C o ( C 0 )
t h e s o l u t i o n developed a p u r p l e b l u e .
c a r b o n y l species were p r e s e n t i n s o l u t i o n .
c o l o u r e d s o l i d separated o u t , which was
a n o n - c a r b o n y l decomposition
product.
On
Co^(C0)^
2
and a
o
Q
Z
o
new
s t o r i n g a t -20°C,a d a r k l y
shown by i n f r a r e d spectroscopy
The
carbonyl product could not
t o be
be
i s o l a t e d from the cetane s o l u t i o n s i n c e the s o l v e n t c o u l d n o t c o n v e n i e n t l y
be removed under vacuum w i t h o u t h e a t i n g and
thus decomposing the p r o d u c t ,
( c e t a n e b . p t . 287°C) and s o l v e n t e x t r a c t i o n w i t h n i t r o m e t h a n e and
a c e t o n i t r i l e caused d e c o m p o s i t i o n ,
y i e l d i n g blue
solutions.
Using hexane as the r e a c t i o n medium, the r e a c t i o n proceeded as
above, a l t h o u g h no band a t t r i b u t a b l e t o Co(C0)^I was
observed.
described
On c o o l i n g
-111-
the red-brown s o l u t i o n a f t e r f i l t r a t i o n , a l i t t l e red-brown s o l i d d e p o s i t e d ,
b u t on warming t o room temperature,
s o l i d ( a t room t e m p e r a t u r e ,
t h i s turned purple.
0*001 mm/Hg) was
u n s u c c e s s f u l , and
spectrum o f the p u r p l e s o l i d showed decomposition
brown mother l i q u o r was
b l a c k p r e c i p i t a t e was
Sublimation of t h i s
the i n f r a r e d
had o c c u r r e d .
The
red-
reduced i n volume, and on c o o l i n g , a second r e d -
o b t a i n e d , whose i n f r a r e d spectrum showed c a r b o n y l
a b s o r p t i o n s , and suggested c o - o r d i n a t e d d i p h e n y l k e t i m i n e .
Before
further
measurements c o u l d be made, t h i s s o l i d became p u r p l e i n c o l o u r , and
further
d e p o s i t s from the mother l i q u o r were a l s o p u r p l e .
(b) Co (C0)
2
g
+ Ph C=N-N=CPh
2
2
No r e a c t i o n o c c u r r e d between equimolar q u a n t i t i e s
of dicobalt
o c t a c a r b o n y l and benzophenone a z i n e on s t i r r i n g i n pentane a t room
H e a t i n g caused f o r m a t i o n o f C o ^ ( C 0 ) ^
was
2
as the o n l y new
i s o l a t e d as b l a c k needle l i k e c r y s t a l s .
unchanged.
S i m i l a r l y , no new
The
c a r b o n y l s p e c i e s , which
a z i n e was
recovered
c a r b o n y l compounds were d e t e c t e d when t h e
r e a c t a n t s , i n t o l u e n e ( i n a s i l i c a f l a s k ) were i r r a d i a t e d .
unreacted a z i n e were a g a i n recovered.
infrared
temperature
The
Co^(C0)^
a
n
a
2
r e a c t i o n s were f o l l o w e d by
spectroscopy.
(b) Co (C0)
2
g
+ 2Ph C=NH
2
D i c o b a l t o c t a c a r b o n y l (1*05 g., 3 mmoles) was
d i s s o l v e d i n pentane
(30 m l . ) i n one arm o f a double Schlenk tube, and d i p h e n y l k e t i m i n e ( 1 m l . ,
6 mmoles), d i l u t e d w i t h pentane (8 m l . ) was
added by s y r i n g e .
r e a c t i o n o c c u r r e d ; v i g o r o u s gas e v o l u t i o n was
An
immediate
observed and a p u r p l e
-112-
p r e c i p i t a t e formed.
A f t e r gas e v o l u t i o n had ceased (~-g-hr.) the dark y e l l o w
mother l i q u o r was removed from the s o l i d by f i l t r a t i o n ,
w i t h pentane u n t i l
and the s o l i d washed
the i n i t i a l l y dark y e l l o w washings were c o l o u r l e s s .
A
s o l u t i o n i n f r a r e d spectrum o f t h e mother l i q u o r and washings showed
( ^ ( C O j g and Co^CcO)^
t o
be the o n l y c a r b o n y l species p r e s e n t .
The p u r p l e
powder whose i n f r a r e d spectrum showed c a r b o n y l groups and c o - o r d i n a t e d
k e t i m i n e was r e c r y s t a l l i s e d from t o l u e n e ( a t 50°C) y i e l d i n g dark p u r p l e
c r y s t a l s ( I ) , b u t a second e x t r a c t i o n o f the crude s o l i d w i t h t o l u e n e a t
90°C caused decomposition
and a b l a c k s o l i d was o b t a i n e d .
R e p e t i t i o n o f the r e a c t i o n by m i x i n g the r e a c t a n t s a t -196°C and a l l o w i n g
the m i x t u r e t o warm up s l o w l y gave the same p u r p l e powder.
Recrystallisation
from monoglyme gave a t a r , b u t w i t h THF/ether, dark p u r p l e c r y s t a l s were
obtained.
A f t e r s t o r i n g f o r s e v e r a l days a t -20°C, e x t r a c t i o n o f the c r y s t a l s
w i t h t o l u e n e l e f t a p a l e p u r p l e r e s i d u e ( I I ) , which s t i l l c o n t a i n e d
carbonyl
and c o - o r d i n a t e d k e t i m i n e groups, as shown by i n f r a r e d spectroscopy.
a d d i t i o n , on p r o l o n g e d
standing, a toluene s o l u t i o n o f I deposited
In
pale
purple, toluene i n s o l u b l e c r y s t a l s o f I I .
Attempted
s u b l i m a t i o n o f I a t room t e m p e r a t u r e , 0*001 mms/Hg was
u n s u c c e s s f u l ; a t 70°C, t h e s o l i d g r a d u a l l y became p a l e grey and the c o l o u r l e s s
l i q u i d which c o l l e c t e d on the c o l d f i n g e r was shown by i n f r a r e d
spectroscopy
to be a m i x t u r e o f d i p h e n y l k e t i m i n e and a l i t t l e benzophenone.
Since a l l t h e ( ^ ( C O j g had not been used up i n the p r e v i o u s p r e p a r a t i o n s ,
the r e a c t i o n was r e p e a t e d by adding p o r t i o n s o f Ph„C=NH t o the C o ( C 0 )
7
fl
-113-
solution.
Thus, a f t e r r e a c t i o n o f Ph C=NH ( 7 mmoles) w i t h Co (CO)g (3*5
2
2
mmoles), the dark y e l l o w mother l i q u o r was removed from t h e p u r p l e
p r e c i p i t a t e and t r e a t e d w i t h a f u r t h e r 3 mmoles o f Ph C—NH.
2
Effervescence
o c c u r r e d and more p u r p l e p r e c i p i t a t e was o b t a i n e d , and a f u r t h e r 3 mmoles o f
Ph C=NH caused f u r t h e r e f f e r v e s c e n c e and p r e c i p i t a t i o n , l e a v i n g an almost
2
c o l o u r l e s s mother l i q u o r .
R e c r y s t a l l i s a t i o n o f the p r e c i p i t a t e s from t o l u e n e /
pentane gave dark p u r p l e c r y s t a l s o f I .
On a l l o w i n g a t o l u e n e s o l u t i o n o f I
to s t a n d f o r s e v e r a l days, p a l e p u r p l e c r y s t a l s o f I I were o b t a i n e d , which
were r e c r y s t a l l i s e d from THF/ether.
A n a l y t i c a l Data.
64-5, 62*3; H, 4-06, 3-85, 4-46; N,6-817 .
0
4*0; N,5'07„.
[Co(Ph C=NH) ][Co(C0) ]
2
6
[Co(Ph C=NH) ][Co(C0) l
2
4
[Co(C0) ]
4
2
4
4
2
I . Found: C,65*3*
I I . Found: C,60'3, 55*6; H,3'7,
r e q u i r e s C,69'9; H,4'4; N,5'4%.
r e q u i r e s C.64'0; H,3'9; N, 5'0%.
2
[Co(Ph C=NH) ]
2
2
N
r e q u i r e s C,62'5; H.2'8; N,3'7%.
R e s u l t s and D i s c u s s i o n
R e a c t i o n between C o _ ( C 0 )
Q
and i o d i n e i n cetane
s o l u t i o n probably
produced a l i t t l e C o ( C 0 ) I , b u t none c o u l d be d e t e c t e d i n hexane s o l u t i o n .
4
A d d i t i o n o f Ph C=NSiMe,j t o these m i x t u r e s produced a new c a r b o n y l compound,
2
p o s s i b l y a k e t i m i n o d e r i v a t i v e , b u t i t s extreme i n s t a b i l i t y has p r e c l u d e d
its identification.
Attempts
t o i n i t i a t e r e a c t i o n between C o ( C 0 ) g and
2
Ph C=N-N=CPh b o t h t h e r m a l l y and p h o t o l y t i c a l l y were u n s u c c e s s f u l .
2
2
Reaction
between Co ( C 0 ) and Ph_C=NH gave a t o l u e n e s o l u b l e c o b a l t c a r b o n y l
2
o
2
u
d i p h e n y l k e t i m i n e d e r i v a t i v e , which on s t a n d i n g changes t o a t o l u e n e i n s o l u b l e
compound, s t i l l
c o n t a i n i n g c a r b o n y l and k e t i m i n e
groups.
Product
475
5-0
55
CoCCO)8
475
50
50
55
I
•
475
5-5
Fig.II.3
-114-
S i n c e v e r y l i t t l e C o ( C O ) ^ I c o u l d be d e t e c t e d i n t h e r e a c t i o n s between
Co (CO)
2
The
and
g
I ,
i t i s probable
2
t h a t Ph C=NSiMe
2
3
reacted with
2
g
p o s s i b i l i t y of t h e — S i M e ^ f r a g m e n t b o n d i n g to t h e c a r b o n y l c a n n o t
ignored,
2 6 3
2 6
' ^
( f r o m Me„SiH and C o „ ( C O ) ) i s a v o l a t i l e
J
/
o
i s much more s t a b l e i n s o l u t i o n .
o
and
Q
Ph C=NSiMe„ h a s
Me^SiCo(CO)^.
probably
similar
0
no
a b s o r p t i o n s due
i n the s o l i d
Thus t h e p r o d u c t
state,
of t h e r e a c t i o n between
s t a b i l i t y p r o p e r t i e s to t h o s e
However, i n f r a r e d e v i d e n c e
absent;
pink
0
compound, w h i c h decomposes s l o w l y a t room t e m p e r a t u r e
Co (C0)
be
e s p e c i a l l y a s many R ^ S i C o C c O ) ^ d e r i v a t i v e s have been r e p o r t e d .
Indeed M e - S i C o C C O ) ,
5
4-
but
Co (CO) .
suggests
of
t h a t t h e compound i s
t o Me^Si c o u l d be d e t e c t e d , and
the
264
spectrum i n the c a r b o n y l r e g i o n d i f f e r s
It
from t h a t r e p o r t e d f o r M e ^ S i C o ( C O ) ^ .
i s p o s s i b l e t h a t the i o d i n e p r e s e n t i n s o l u t i o n c o u l d h a v e r e a c t e d w i t h
the Me^Si f r a g m e n t to g i v e M e ^ S i l , a l t h o u g h
The
pentane s o l u t i o n i n f r a r e d
product
Co^(CO)^
i s shown i n F i g . 1 1 3
2
probably
i n pentane.
o c c u r s , no
p o s i t i o n s and
no e v i d e n c e
f o r t h i s was
spectrum i n the c a r b o n y l r e g i o n of
the
t o g e t h e r w i t h t h e s p e c t r a of C o ( C O ) g
deductions
and
2
S i n c e o v e r l a p o f bonds due
to p r o d u c t
and
about t h e n a t u r e o f t h e p r o d u c t
r e l a t i v e i n t e n s i t i e s of i t s carbonyl
obtained.
Co^(CO)^
from
2
the
stretching frequencies,
can be made.
The
attempts
b o t h t h e r m a l l y and
C o ^ ( C O ) ^ , and
2
to i n i t i a t e r e a c t i o n between C o ( C O ) g and
2
photolytically,
l e a d to decomposition
r e c o v e r y of t h e u n r e a c t e d
c o n d i t i o n s n e c e s s a r y to r u p t u r e
t h e N-N
azine.
Ph C=N-N=CPh ,
2
2
of Co (CO)g
2
I t i s apparent
to
that
bond i n t h e a z i n e would be
too
-115-
s e v e r e f o r the c a r b o n y l , w h i c h would decompose b e f o r e r e a c t i o n c o u l d
R e a c t i o n between n i t r o g e n b a s e s and ( ^ ( C O ^ n o r m a l l y
p o r t i o n a t i o n to y i e l d
causes d i s p r o -
s a l t s o f the t y p e [ C o L ^ ] [ C o ( C O ) ^ ] ^ ( n = 4 or
u s u a l l y ) ^ , as d e s c r i b e d i n Chapter
I.
However, t h e p r o d u c t
6,
( I ) obtained
from the r e a c t i o n of ( ^ ( C C O g w i t h Pti2C=NH does n o t appear to be o f
type.
I t s solubility
this
i n t o l u e n e s u g g e s t s i t i s c o v a l e n t r a t h e r than
i n n a t u r e , but u n f o r t u n a t e l y attempts
measurements i n n i t r o b e n z e n e
compound.
occur.
to c o n f i r m
t h i s by c o n d u c t i v i t y
s o l u t i o n r e s u l t e d i n decomposition
A t o l u e n e s o l u t i o n of the d a r k p u r p l e complex, I , on
standing deposits pale purple c r y s t a l s
ionic,
of complex I I .
of
the
prolonged
Both t h e s e c o m p l e x e s
c o n t a i n c a r b o n y l groups and c o - o r d i n a t e d d i p h e n y l k e t i m i n e , a s shown by
infrared
s p e c t r o s c o p y , and b o t h a r e a i r - s e n s i t i v e ,
complex I b e i n g
especially
so.
Since diphenylketimine
expected
[Co
+ I I
product
seems to b e h a v e a s a weak base^^'^^''",
from t h e r e a c t i o n o f ( ^ ( C C O g and
(Ph„C=NH) ] [ C o
2
n
- I
(CO).] .
4 Z
0
Pti2C=NH i s
Complex I I i s t e n t a t i v e l y f o r m u l a t e d
t y p e of complex. T h i s i s s u p p o r t e d
by
the i n f r a r e d
spectrum
t h e c a r b o n y l r e g i o n , w h i c h shows a v e r y s t r o n g , b r o a d
a l s o a s h o u l d e r a t 1910
cm
The
cm
s t r o n g peak a t 1883
weak bands a r e p e r h a p s
due
-1
-1
and
the
i s attributable
to i m p u r i t y .
complex I I a r e c o n s i s t e n t w i t h an i o n i c
The
to [ C o ( C O ) ^ ]
-4
cm
and
2000
and
the
^, but
cm
s o l u b i l i t y p r o p e r t i e s of
and
a c e t o n e , but a t t e m p t s
-1
other
formulation: i t i s insoluble i n
t o l u e n e , p e n t a n e , e t h e r but s o l u b l e i n THF
this
(Nujol mull) i n
peak a t 1883
two v e r y weak bands a t 2012
as
to
-116-
o b t a i n c o n d u c t i v i t y measurements i n n i t r o b e n z e n e
l e a d to decomposition.
A
c o m p a r i s o n o f t h e p r o p e r t i e s o f complex I I and o t h e r compounds o f t h e t y p e
[CoL ][Co(CO).]„ s u p p o r t s an a n i o n i c f o r m u l a t i o n .
n
4 L
T h e s e compounds a r e a i r
s e n s i t i v e , d a r k r e d , and i n s o l u b l e i n h y d r o c a r b o n s o l v e n t s , b u t s o l u b l e i n
252 253
THF and a c e t o n e .
'
However,
t h e a n a l y t i c a l d a t a o b t a i n e d on I I and
r e p o r t e d i n t h e p r e v i o u s s e c t i o n i s i n c o n s i s t e n t , and does n o t r e a l l y
any
formulation of t h i s
type.
The i n f r a r e d s p e c t r u m
support
o f complex I I shows bands
due t o c o - o r d i n a t e d k e t i m i n e , w i t h v„ „ a t 3268 cm * and v„ „ a t 1607 cm
N-H
C=N
The n a t u r e o f complex I i s u n c e r t a i n .
was a g a i n o b t a i n e d , a l t h o u g h
t h e complex f a l l s on c h a n g i n g
Inconsistent analytical
t h i s d a t a s u g g e s t s t h a t t h e "L c a r b o n
t o complex I I .
samples,
c l e a r whether t h e i n c o n s i s t e n c i e s a r e due t o t h e s a m p l e s ,
u n r e l i a b i l i t y o f t h e a n a l y t i c a l methods
Complex I
extremely
ionic.
s o l u b l e i n THF, monoglyme and a c e t o n e ,
figures
and i t i s n o t
or to t h e
f o r complexes of t h i s
i s i n s o l u b l e i n pentane, but r e a d i l y
The i n f r a r e d spectrum
content of
Some o f t h e a n a l y t i c a l
f o r c o m p l e x e s I and I I were o b t a i n e d on d i f f e r e n t
data
type.
s o l u b l e i n t o l u e n e and
and i s thus p r o b a b l y n o t
( N u j o l m u l l ) i n t h e c a r b o n y l r e g i o n shows a
weak band a t 2008 cm"''" and a s t r o n g b r o a d band r e s o l v e d i n t o 3 maxima a t
-
1905, 1869 and 1842 cm *. I n a d d i t i o n bands a t t r i b u t a b l e t o c o - o r d i n a t e d
Ph„C=NH a r e o b s e r v e d , w i t h v„ „ a t 3257 c m
and v „ a t 1605 and 1594 cm" .
2
'
N-H
C=N
- 1
Complexes o f t h e t y p e [Cp(.C0)^L]
?
w i t h e.g. PPh^ h a v e been o b t a i n e d by
d i r e c t r e a c t i o n of the l i g a n d with C o ( C 0 ) .
2
infrared
spectrum
1
g
s
o f [CoCcO^PPh^l ^ *- s i m i l a r
The c a r b o n y l p a t t e r n i n t h e
to that observed
f o r complex I
-117-
(bands a t 2030(vw), 1960m,(sh), 1 9 5 0 ( v s ) , 1902(vw)) although
in
I are considerably shifted
of t h e t y p e
to lower
frequencies.
[Co(CO)2Ph2C=NH]^ would n o t a c c o u n t
Ph2C=NH were r e q u i r e d t o r e a c t c o m p l e t e l y
However, a f o r m u l a t i o n
f o r the f a c t
was o b s e r v e d ,
parent
t h a t 4 moles o f
w i t h 2 m o l e s o f COgCCO^.
A t t e m p t s were made t o o b t a i n a mass s p e c t r u m o f complex I .
180
the absorptions
A peak a t m/e
due t o Pb^C^N* and s e v e r a l p e a k s t o h i g h e r m/e, b u t no
peak c o u l d be i d e n t i f i e d .
Thus r e a c t i o n between ( ^ ( C O ^
complex w h i c h i s p r o b a b l y
and Pti2C=NH o c c u r s t o p r o d u c e a p u r p l e
o f t h e type
i n t e r m e d i a t e complex i s i s o l a t e d
[CoL ][Co(CO)^]^
initially
n
(n = 4 ? ) .
An
i n the r e a c t i o n , which changes
i n t o t h e i o n i c complex, b u t t h e n a t u r e o f t h e i n t e r m e d i a t e c o u l d n o t be
determined.
Conclusions
R e a c t i o n s o f d i p h e n y l k e t i m i n e and i t s d e r i v a t i v e s w i t h
c o b a l t and n i c k e l
systems
non-carbonyl
show t h a t t h e n e u t r a l l i g a n d b e h a v e s a s a n o r m a l
b a s e towards t r a n s i t i o n m e t a l s .
Attempts to i n t r o d u c e diphenylketimine a s
an a n i o n i c l i g a n d i n t o c o m p l e x e s were u n s u c c e s s f u l ; i n some c a s e s , r e a c t i o n
did
not occur, i n other cases n o n - c r y s t a l l i a a b l e
other r e a c t i o n s , the anion
t a r s were o b t a i n e d ,
and i n
a b s t r a c t e d h y d r o g e n , p o s s i b l y from t h e s o l v e n t t o
y i e l d complexes c o n t a i n i n g the n e u t r a l l i g a n d .
In
c o b a l t carbonyl systems,
r e a c t i o n o c c u r s between t h e c a r b o n y l and
l i g a n d , b u t i n one c a s e t h e p r o d u c t
the o t h e r , f u l l
was e x t r e m e l y
c h a r a c t e r i s a t i o n of the products
t h e r m a l l y u n s t a b l e , and i n
h a s n o t been p o s s i b l e .
CHAPTER THREE
Reactions of Diphenylketiminodiphenylmethylchloride
T r a n s i t i o n M e t a l Complexes
with
-118-
A.
Introduction
The
e v i d e n t u n w i l l i n g n e s s o f d i p h e n y l k e t i m i n e to form
isolable
d e r i v a t i v e s c o n t a i n i n g t h e l i g a n d a s an a n i o n i c group, i n t h e s y s t e m s
described
i n Chapter
I I l e a d t o a change o f e m p h a s i s i n t h e s t u d y o f un-
saturated nitrogen ligands with t r a n s i t i o n metals.
e n c o u r a g e d by t h e p r e p a r a t i o n o f t h e pseudo a l l y l
The change was p a r t i c u l a r 1
complex
130
[rt-CpMo(CO) Ph CNCPh ]
2
attempts
2
by an i n d i r e c t r o u t e .
2
to p r e p a r e
T h i s chapter d e s c r i b e s
a n a l o g o u s compounds d i r e c t l y
from
diphenylketiminodi-
p h e n y l m e t h y l c h l o r i d e , P h C = N C ( C l ) P h , w h i c h was p r e p a r e d from d i p h e n y l 267 268
k e t i m i n o l i t h i u m , P h C = N L i and d i c h l o r o d i p h e n y l m e t h a n e .
'
I t i s b e l i e v e d t h a t t h e P h C N C P h group i n t h e molybdenum complex i s
2
2
2
2
2
130
bonding to t h e m e t a l
concerned
a s a p s e u d o - a l l y l group
and s i n c e t h i s c h a p t e r i s
with the attempted p r e p a r a t i o n of p s e u d o - a l l y l complexes, i t i s
r e l e v a n t a t t h i s s t a g e t o comment on t h e c h e m i s t r y o f t r a n s i t i o n m e t a l
complexes themselves.
appeared.
metals
allyl
Numerous complexes a r e known and s e v e r a l r e v i e w s
>270 ,271
j t - a l l y l c o m p l e x e s h a v e been p r e p a r e d
have
for several
e.g. ( i T - C . j H ^ ) N i , (it-C^H^^Mo, b u t t h e m a j o r i t y o f t h e d e r i v a t i v e s
2
c o n t a i n o t h e r g r o u p s a l s o , e.g. it-C H,.Mo(C0) Jt-C H,-, and it-C H,-Co(CO) PPh.j.
3
rt-allyl
2
5
3
d e r i v a t i v e s i n w h i c h one or more o f t h e p r o t o n s
o t h e r groups e.g. a l k y l g r o u p s o r h a l o g e n s
need n o t be " f r e e " b u t c a n be p a r t o f a r i n g
and
atoms.
III.2.
i s r e p l a c e d by
a r e a l s o common, e.g.
Tt-C^HgMn(CO)^, 1 , 1 - d i m c t h y l a l l y l m a n g a n e s e t e t r a c a r b o n y l .
carbon
2
system
The n - a l l y l
group
or a long c h a i n o f
E x a m p l e s o f t h e s e t y p e s o f compound a r e shown i n F i g s .
III.l
-119-
Ph
-CI
Pd
Ph
C
Ph
\C
Ph
Ni
2
OEt
Fig.III.2.
Fig.III.1.
Several
n-allyl
d e r i v a t i v e s have v e r s a t i l e c a t a l y t i c p r o p e r t i e s
Ni(jt-C,jH,-^ c a t a l y s e s
and
a m i x t u r e of
the
t r i m e r i s a t i o n of b u t a d i e n e to
(jt-C.jH|-)Ni(Br)PR.j) and
e.g.
cyclododecatriene,
E t A l C ^ catalyses
the
dimerisation
271
of
e t h y l e n e to b u t e n e .
The
fairly
bonding i n j r - a l l y l
t r a n s i t i o n m e t a l c o m p l e x e s can
r e a d i l y i n a q u a l i t a t i v e manner.
group form an
(or nearly
so)
schematically
The
be
3 c a r b o n atoms of
understood
the
jr-allyl
i s o s c e l e s t r i a n g l e w i t h t h e m e t a l atom i n a p l a n e p e r p e n d i c u l
to
for
the
p l a n e of
the
triangle.
the b i s - 2 - m e t h y l a l l y l
This
is
illustrated
n i c k e l complex F i g . I I I . 3 .
H„C
CH
Ni
CH
Fig.III.3.
z
•3
¥2
6>
X
0
y
ROC
ROC
M
Fig.III-4.
R e p r e s e n t a t i o n of n - a l ' i y l m o l e c u l a r o r b i t a l s ,
w i t h ' w h i c h t h e y a r e most l i k e l y
allyl
bonding.
to i n t e r a c t
and
the metal
orbitals
to g i v e s u b s t a n t i a l
metal-
-120-
The t h r e e pit o r b i t a l s o f t h e a l l y l
group form t h r e e M.O.s, w h i c h a r e
represented
with
a r e most
in Fig.III.4,
likely
together
to i n t e r a c t ,
p i c t o r i a l manner, s i n c e t h e l o c a l
For
arguments a l o n e
example, t h e d
plane
(i.e.
These
from o v e r l a p c o n s i d e r a t i o n s , i n a rough,
symmetry
o f t h e jt-C,H,--M i s v e r y low (C )
l e a d to a l a r g e number of p o s s i b l e
combinations.
and d 2 ^2 o r b i t a l s l i e i n a p l a n e below t h e a l l y l
x
they a r e n o t d i r e c t e d towards t h e l i g a n d ) and a r e l i k e l y
non-bonding.
they
t o g i v e s u b s t a n t i a l m e t a l - a l l y l bonding.
combinations a r e a r r i v e d a t mainly
and symmetry
the metal o r b i t a l s w i t h which
t o be
F u r t h e r d i s t i n c t i o n s a r e made on t h e b a s i s t h a t m e t a l and
ligand o r b i t a l s having
larger overlap
than
c o i n c i d e n t nodal
p l a n e s a r e more l i k e l y
to have a
t h o s e w h i c h do n o t c o i n c i d e .
M
(a)
(b)
Fig.III.5.
Considering
a p s e u d o - a l l y l i c l i g a n d , replacement
c e n t r a l -CR-
group i n t h e a l l y l i c
group
of a n i t r o g e n atom f o r t h e
R
>^*»v
R C^'""^CR
2
qualitatively
the jt-molecular o r b i t a l s of the a l l y l i c
w i l l not
alter
2
group.
However t h e
2
n i t r o g e n p o s s e s s e s a l o n e p a i r of e l e c t r o n s w h i c h w i l l
be i n an sp
orbital,
-121-
d i r e c t e d a s shown I n F i g . I I I . 5 ,
and
the e f f e c t of t h e l o n e p a i r on t h e bonding
must be c o n s i d e r e d .
Two
III.5.
I n structure
(a) i t will
to
i n the a l l y l
c o m p l e x e s d e s c r i b e d above.
that
extreme p o s i t i o n s f o r the metal
be r e a d i l y s e e n , t h a t
a r e shown i n F i g .
the bonding i s
I n s t r u c t u r e ( b ) the
n i t r o g e n l o n e p a i r a-bonds t o the m e t a l , but s u i t a b l e m e t a l
still
available
pseudo-allylic
If
analogous
orbitals
are
to o v e r l a p w i t h t h e *^ and *^ r r - m o l e c u l a r o r b i t a l s of
the
ligand.
o t h e r c o m p l e x e s c o n t a i n i n g the -RC=NR s y s t e m a r e c o n s i d e r e d , t h e n i t
i s obvious
t h a t e i t h e r an M-N CT bond c a n be formed, a s f o r example, i n t h e
125
d i a z a b u t a d i e n e molybdenum c o m p l e x e s
126
'
d e s c r i b e d i n Chapter
I
(p.35),
24
or
n-bonds a r e formed a s i n t h e i r o n complex (PhCI-I=CII-CH=NPh)FeCO)
s t r u c t u r e i s shown i n C h a p t e r
I (p.63, F i g . I . l l k ( i ) ) .
The
3
, whose
s t r u c t u r e of
the
232
n i c k e l complex [ N i ( C ^ H ^ N - C = N ) ( C O ) ] ^
has a l s o been d e s c r i b e d i n C h a p t e r
0
I
(p.80, F i g . I . 1 7 ) .
I n t h i s complex, t h e l o n e p a i r on t h e -C=N
atom o-bonds to one N i atom, and
t h e -C=N
A few N - h e t e r o c y c l i c a n a l o g u e s
h a v e been p r e p a r e d , but
because
t h e y a r e i n g e n e r a l much l e s s
t h e n - s y s t e m of t h e r i n g
n e g a t i v e n i t r o g e n atom and
so t h a t
t h e M-L
group it-bonds to a n o t h e r N i atom.
of i t - c y c l o p e n t a d i e n y l m e t a l
p e n t a d i e n y l c o m p l e x e s , and more d i f f i c u l t
nitrogen
to p r e p a r e .
i s d i s t o r t e d by
complexes
s t a b l e than t h e c y c l o T h i s i s probably
t h e p r e s e n c e of an
electro-
l e s s a v a i l a b l e f o r s y m m e t r i c a l bonding to the m e t a l ,
jt-bond i s w e a k e r .
The
compounds shown i n F i g s . I I I . 6
I I I . 7, n - p y r r o l y l m a n g a n e s e t r i c a r b o n y l ' ' ' ^ and a z a f e r r o c e n e ^ " ^ ^ ,
both have s i m i l a r p h y s i c a l p r o p e r t i e s t o t h o s e of the p a r e n t
and
respectively
n-cyclopenta-
-122-
d i e n y l complexes, but
t h e n i t r o g e n atom i n t h e C^H^N r i n g i s o n l y w e a k l y
basic.
t h a t the l o n e p a i r on
T h i s suggests
i n v o l v e d i n M-L
bonding.
w i t h t h e r i n g and
for
The
the n i t r o g e n i s to some e x t e n t
l o n e p a i r i s i n an o r b i t a l w h i c h i s c o p l a n a r
t h u s d i r e c t e d away from t h e m e t a l ,
a s would be
the c a s e
a p s e u d o - a l l y l complex h a v i n g
t h e s t r u c t u r e shown i n F i g . I l l . 5 ( a ) .
N
N
M
0
c
c
c
o
Fig.III.6.
Thus by
metal
Fig.III.7.
c o m p a r i s o n w i t h o t h e r c o m p l e x e s , i t would a p p e a r t h a t
c o u l d be
i n e i t h e r of the p o s i t i o n s i n d i c a t e d i n F i g . I I I . 5 .
i n t e r m e d i a t e between t h e two
atom i s n e a r e r
involvement
on
be more l i k e l y ,
to t h e n i t r o g e n , r a t h e r t h a n
of t h e n i t r o g e n l o n e p a i r .
the carbon
bulky
e x t r e m e s may
atoms w i l l
groups tending
I t i s likely
h a v e some e f f e c t on
to f o r c e the m e t a l
be d i s c u s s e d i n S e c t i o n C.
the c a r b o n
the
A position
i n which the
atoms, b e c a u s e
metal
of
that the s u b s t i t u e n t s
the p o s i t i o n o f the
n e a r e r to the n i t r o g e n .
metal,
This
will
-123-
The
t u n g s t e n p s e u d o - a l l y l complex [rt-CpW(CO) Ph CNCPh ]
2
prepared
by t h e r e a c t i o n o f
rt-CpW(CO).jCl
2
261
2
h a s been
w i t h 2 m o l e s o f P h C = N L i , and i s
2
130
similar
to t h e v e r y s t a b l e molybdenum complex.
molecules
Ph CNCPh
2
I n t h e r e a c t i o n , two
o f P h C = N L i must " c o n d e n s e " i n some manner, to g i v e t h e
2
moiety.
2
The n i t r o g e n atom w h i c h i s e l i m i n a t e d i n t h i s p r o c e s s h a s
been d e t e c t e d a s l i t h i u m i s o c y a n a t e , w h i c h i s mixed w i t h t h e l i t h i u m c h l o r i d e
which p r e c i p i t a t e s out d u r i n g
the r e a c t i o n . A t t e m p t s
to p r e p a r e t h e
p s e u d o - a l l y l molybdenum compound by r e a c t i n g P h C = N - C ( C l ) P h
2
Na[ir-CpMo(C0) ] i n THF, d i m e t h y l
3
a s t h e main p r o d u c t ,
formamide and d i g l y m e gave [ jt-CpMo(C0) ]
3
p s e u d o - a l l y l compounds d i r e c t l y
reacted with s e v e r a l metal
2
7
1
2
The l i g a n d i t s e l f
2
h a l i d e s h a v e y i e l d e d numerous i t - a l l y l
2
1)
N a [ M n ( C 0 ) ] + ClCH CH=CH
+
2
2
>
i n t h e f o l l o w i n g schemes
(CO) Mn(o-CH CH=CH )
5
2
u. v .
or 80°
(COXMndt-C-H,.)
4
3 5
was
analogous
c o m p l e x e s , and
:
5
unchanged.
to s y n t h e s i s e
c a r b o n y l and n o n - c a r b o n y l d e r i v a t i v e s ;
1-3 )
'
i n attempts
from P h C = N - C P h C l .
some o f t h e s e r e a c t i o n s a r e i l l u s t r a t e d
9
2
one o t h e r c a r b o n y l complex were d e t e c t e d b u t c o u l d
Two g e n e r a l methods o f p r e p a r a t i o n were u s e d
6
with
and most o f t h e o r g a n i c l i g a n d was r e c o v e r e d
S m a l l amounts o f a t l e a s t
.
. ,
„ 251
n o t be i s o l a t e d .
r e a c t i o n s of a l l y l
2
2
(equations
-124-
2)
Ni(C0)
+ CH =CH-CH -X
4
2
(X =
3)
— [ i t - C ^ N i X ]
2
Br,I)
Pd ( m e t a l ) + CH =CH-CH Br
2
The
v a r i e t y of
the l i g a n d ,
>
2
s e c o n d method of p r e p a r a t i o n
d e r i v a t i v e of
2
[jt-C H PdBr]
3
used involved
(PhgCNCPh,, )MgCl, and
t r a n s i t i o n metal systems.
5
2
s y n t h e s i s of
r e a c t i o n of
Again a l l y l Grignard
the
this with
,
/
.
schemes ( e q u a t i o n s
4)
5)
5
T
H
F
the
> (jt-C H )Ni(it-C H )
2
5
N i C l _ + C,H,.MgCl — - — >
2
3 5
_ o
1 0
Since
in
.
i i - \ 269,271
4 and 5 ) :
(it-C H ) Ni + C^MgCl
5
a
r e a g e n t s have
been used to p r e p a r e a l l y l - t r a n s i t i o n metal complexes, as i l l u s t r a t e d
*
,
following
Grignard
c
5
3
5
(rt-C-Hj-Ni
3 5 2
the d i r e c t r e a c t i o n between P h C = N - C ( C l ) P h
2
2
and
Na[jt-CpMo(CO) ]
3
251
failed
to p r o d u c e the p s e u d o - a l l y l d e r i v a t i v e
other metals.
I n p a r t i c u l a r , the r e a c t i o n s of P h C = N - C ( C l ) P h
2
manganese c a r b o n y l
d e r i v a t i v e s , and
i n v e s t i g a t e d , as a l l y l
Allyl-nickel
, a t t e n t i o n was
with
compounds of b o t h t h e s e
Another c o n s i d e r a t i o n
t h a t t h e m e t a l s t o w a r d s the l e f t - h a n d
general
side.
with
s y s t e m s h a v e been p r e p a r e d .
h a v e been p r e p a r e d i n a
i n choosing which metal to study
s i d e of
the P e r i o d i c T a b l e tend
form more s t a b l e c o m p l e x e s w i t h n i t r o g e n - c o n t a i n i n g
towards t h e r i g h t - h a n d
ligands
t h a n the
to
ones
I n p a r t i c u l a r manganese ( + l ) c o m p l e x e s i n
seem e s p e c i a l l y s t a b l e .
on
some n i c k e l c o m p l e x e s were
c o m p l e x e s e s p e c i a l l y a r e common, and
v a r i e t y o f ways.
2
focussed
was
-125-
B.
Experimental
1.
Na[Mn(CO) ] +
Ph C=NC(Cl)Ph
5
Sodium manganese
2
2
p e n t a c a r b o n y l was p r e p a r e d
v i g o r o u s l y s t i r r i n g dimanganese d e c a c a r b o n y l
i n t h e u s u a l way,
by
( 1 g., 2*5 mmoles) w i t h an
272
e x c e s s o f an a p p r o x i m a t e l y
1% sodium amalgam i n THF
y e l l o w colour of M i ^ C C O ) ^ disappeared
removed
(20 m l . ) .
When t h e
( 2 h r s . ) , most o f t h e amalgam was
from the r e a c t i o n f l a s k v i a a tap a t t h e bottom, and d i p h e n y l -
k e t i m i n o d i p h e n y l m e t h y l c h l o r i d e ( 1 * 9 g., 5 m m o l e s ) , i n THF ( 1 5 m l . ) was
added.
i.r.
A f t e r o v e r n i g h t s t i r r i n g and t h e n r e f l u x i n g
s p e c t r o s c o p y showed
t h a t t h e main c a r b o n y l p r o d u c t was manganese
but new a b s o r p t i o n s were d e t e c t e d a t 2110, 2062 and
Mn (C0)
2
1 Q
( ~ 2 0 % ) and P h C = N - C ( C l ) P h
2
to i s o l a t e t h e p r o d u c t
in
for 5 hrs., solution
failed,
2
2026 cm~*.
carbonyl,
Both
( ~ 4 0 % ) were r e c o v e r e d , b u t a l l a t t e m p t s
s i n c e i t appeared
t o decompose
i n t o Mn (C0)^Q
2
solution.
2.
Mn(C0) Br +
Manganese
5
Ph C=N-C(Cl)Ph
2
2
pentacarbonylj[was d i s s o l v e d i n chloroform
(6 m l . ) .
Diphenyl-
k e t i m i n o d i p h e n y l m e t h y l c h l o r i d e ( 0 ' 3 8 g., 1 mmole) was d i s s o l v e d i n c h l o r o f o r m
( 1 2 m l . ) and a t h i r d o f t h i s s o l u t i o n
the c a r b o n y l s o l u t i o n .
( 0 * 3 3 mmoles P h C = N - C ( C l ) P h ) added t o
2
The r e a c t i o n was f o l l o w e d by w i t h d r a w i n g
t h e s o l u t i o n p e r i o d i c a l l y , and r e c o r d i n g t h e i r
carbonyl region.
2
infrared
A f t e r s t i r r i n g a t room t e m p e r a t u r e
samples of
s p e c t r a i n the
f o r 3^- h r s . ( p r o t e c t e d
from t h e l i g h t ) a s m a l l amount o f w h i t e p r e c i p i t a t e was o b s e r v e d and
c a r b o n y l bands were d e t e c t e d , b u t t h e b u l k o f t h e Mn(C0),-Br r e m a i n e d .
new
The
-127-
washed r a p i d l y w i t h hexane and
was
shown to be
t e t r a p h e n y l e t h y l e n e , on
spectroscopic data.
C
H
r
26 20
e
(
l
u
i
r
e
s
C,94-0; H,6«0%.
A v e r a g e C,94«4%.
M.Pt. 218°C ( l i t .
identical
T h i s compound
223°C).
infrared
H,5'l%.
The
infrared
to the s p e c t r u m o f an a u t h e n t i c sample.
r e s i d u e a f t e r e t h e r e x t r a c t i o n was
t e s t s showed the p r e s e n c e
( Y i e l d , 0*2 g . ) .
t h e b a s i s of a n a l y t i c a l and
Found: C,94*9, 93'9%.
s p e c t r u m ( N u j o l m u l l ) was
The
pumped d r y .
o f n i c k e l and
p a l e brown i n c o l o u r and
chlorine.
The
infrared
elemental
spectrum
of
the r e s i d u e showed o n l y weak a b s o r p t i o n s .
( b ) I n a r e p e a t of
night
stirring
recovered
by
left
a black
sublimation
y e l l o w s o l i d w h i c h was
Analytical
and
the r e a c t i o n , r e m o v a l of the s o l v e n t a f t e r
t a r , from w h i c h u n r e a c t e d
nickelocene
,
over-
w
( ' 5 0 % ) was
( a t 50°C, 0*001 mm/Hg). E t h e r e x t r a c t i o n y i e l d e d a
shown to c o n t a i n n i c k e l
spectroscopic data
suggested
o r g a n i c l i g a n d s bonded to n i c k e l .
(by elemental
tests).
t h a t t h i s compound c o n t a i n s
I t does n o t
c o n t a i n h a l o g e n , nor
a it-
c y c l o p e n t a d i e n y l group.
( c ) No
r e a c t i o n occurred
d i p h e n y l m e t h y l c h l o r i d e on
stirring
compound can be r e c r y s t a l l i s e d
g r e e n s o l u t i o n of n i c k e l o c e n e
5
between n i c k e l o c e n e and
i n toluene
from c h l o r o f o r m
i n chloroform
f o r 16 h r s .
without
showed no
diphenylketiminoThe
organic
d e c o m p o s i t i o n , and
change over a p e r i o d
days.
4.
N K C O ) , -I- P h C = N - C ( C l ) P h
2
2
Diphenylketiminodiphenylmethyl c h l o r i d e (
toluene
(
30 m l . )
to g i v e a y e l l o w s o l u t i o n .
1 g.) was
dissolved in
Tetracarbonyl n i c k e l ,
after
a
of
-128-
b e i n g d r i e d by s t a n d i n g over anhydrous CuSO^, was
o f n i t r o g e n onto the Ph2C=NC(Cl)Ph
(M.Pt. Ni(CO)^ -18'9°C).
2
condensed out o f a
stream
s o l u t i o n by c o o l i n g t h e l a t t e r t o -78°C
Excess Ni(CO)^ was used i n each r e a c t i o n , the exact
q u a n t i t y n o t b e i n g determined
due
t o t h e d i f f i c u l t i e s o f h a n d l i n g the
extremely v o l a t i l e , t o x i c carbonyl.
No change was
observed a t room
v
t e m p e r a t u r e , b u t on c a r e f u l warming to* 40°C, c o n s i d e r a b l e d a r k e n i n g i n
c o l o u r o f the s o l u t i o n and a b l a c k p r e c i p i t a t e were observed a f t e r ^ 3 0 mins.
A f t e r 5 h r s . , no f u r t h e r change was
was
observed and a f t e r c o o l i n g , the s o l u t i o n
f l u s h e d out w i t h n i t r o g e n t o remove any u n r e a c t e d Ni(CO)^.
r e s i d u e a f t e r f i l t r a t i o n was
f i n e l y divided Ni.
The
The
red f i l t r a t e y i e l d e d a
r e d s o l i d which y i e l d e d p a l e y e l l o w c r y s t a l s on r e c r y s t a l l i s a t i o n
toluene/hexane.
2
R e s u l t s and
and
2
Ph C=CPh .
2
2
Discussion
o f d i p h e n y l k e t i m i n o d i p h e n y l m e t h y l c h l o r i d e w i t h sodium
manganese p e n t a c a r b o n y l
studied.
from
A n a l y t i c a l and i n f r a r e d s p e c t r o s c o p i c data suggested t h a t
the c r y s t a l s c o n s i s t e d o f Ph C=N-C(Cl)Ph
Reactions
black
and w i t h manganese p e n t a c a r b o n y l bromide have been
The main p r o d u c t i n the r e a c t i o n o f the sodium s a l t i s the dimer,
Mn (C0)^Q, a l t h o u g h a new
c a r b o n y l species was
2
detected spectroscopically.
S e p a r a t i o n o f t h i s species from Mn (C0)^Q c o u l d n o t be e f f e c t e d , s i n c e i t
2
seemed t o decompose i n t o Mn (C0)^g i n s o l u t i o n .
2
s o l u t i o n o f Ph C-NC(Cl)Ph
2
2
Warming a c h l o r o f o r m
and Mn(C0)^Br caused r e a c t i o n t o occur, w i t h
f o r m a t i o n of the complex Mn(CO)^(Ph CNCPh ).
2
2
I n t h e r e a c t i o n s o f n i c k e l o c e n e and n i c k e l t e t r a c a r b o n y l w i t h d i p h e n y l -
-129-
k e t i m i n o d i p h e n y l m e t h y l c h l o r i d e , no f u l l y c h a r a c t e r i s e d complexes c o n t a i n i n g
n i c k e l and t h e o r g a n i c l i g a n d c o u l d be o b t a i n e d .
I n each case, though, t h e
i n f o r m a t i o n o h t a i n e d shows t h a t , i n t h e former case a t l e a s t , r e a c t i o n d i d
occur.
I n t h e r e a c t i o n o f Na[Mn(CO) ] w i t h Ph C=N-C(Cl)Ph , a c o n s i d e r a b l e
5
2
2
q u a n t i t y o f Mn^CO).^ was d e t e c t e d q u i t e e a r l y d u r i n g t h e r e a c t i o n , w h i l e
some u n r e a c t e d
sodium s a l t and o r g a n i c l i g a n d were s t i l l p r e s e n t , and i t seems
l i k e l y t h a t f o r m a t i o n o f t h e d i m e r i c c a r b o n y l d i r e c t l y from t h e sodium s a l t
i s t h e main r e a c t i o n .
However, a s m a l l amount o f a new c a r b o n y l complex was
d e t e c t e d s p e c t r o s c o p i c a l l y a f t e r r e f l u x i n g t h e m i x t u r e ; removal o f
Mn (cO)^Q
2
and Ph C=N-C(Cl)Ph by e x t r a c t i o n w i t h hexane and t o l u e n e , r e s p e c t i v e l y
2
2
l e f t a s m a l l amount o f green s o l i d which gave a green s o l u t i o n when d i s s o l v e d
i n CHCl^.
However, t h e i n f r a r e d spectrum o f t h i s s o l u t i o n which t u r n e d
y e l l o w on s t a n d i n g , showed M ^ C C O ) ^ t o be p r e s e n t as w e l l as t h e new
c a r b o n y l complex, i n d i c a t i n g t h a t t h e complex decomposes t o Mn^CCO)^ i n
s o l u t i o n , and s a t i s f a c t o r y p u r i f i c a t i o n o f t h i s s m a l l amount o f p r o d u c t
n o t be
could
achieved.
T h i s r e a c t i o n can be compared t o t h a t between Na[ jr-CpMo(CO),j] and
251
Ph2C=N-C(Cl)Ph
2
, where t h e main r e a c t i o n was decomposition
o f t h e sodium
s a l t t o t h e d i m e r , [it-CpMo(CO) ] , a l t h o u g h a new c a r b o n y l complex i n s m a l l
3
2
amounts was d e t e c t e d s p e c t r o s c o p i c a l l y .
Warming a c h l o r o f o r m s o l u t i o n o f Mn(CO) Br and Ph C=N-C(Cl)Ph
5
2
2
gave a
new c a r b o n y l complex, Mn(CO)^(Ph CNCPh ), o b t a i n e d as a p a l e y e l l o w powder.
2
2
-130-
The complex decomposed f a i r l y r a p i d l y i n s o l u t i o n t o a w h i t e n o n - c a r b o n y l
m a t e r i a l , b u t i s s t a b l e f o r l o n g e r p e r i o d s i n the s o l i d s t a t e .
I t d i d not
m e l t , b u t on b e i n g heated i n a tube s e a l e d under n i t r o g e n , i t began t o darken
a t "'80°C and c o n t i n u e d
It
t o darken and s o f t e n t o a dark orange t a r , up t o
200°C
i s v e r y s o l u b l e i n CHCl^, acetone, somewhat s o l u b l e i n benzene and t o l u e n e
and
s l i g h t l y s o l u b l e i n pentane.
The bands i n t h e i n f r a r e d spectrum o f t h e s o l i d are recorded
III.l,
t o g e t h e r w i t h those o f Ph2C=N-C(Cl)Ph
2
i n Table
and known assignments.
A CHCl^
s o l u t i o n o f t h e complex shows c a r b o n y l a b s o r p t i o n s a t 2104(w), 2 0 3 3 ( s ) ,
2020(sh),
1 9 6 5 ( s ) cm ^.
These band p o s i t i o n s can be compared t o t h e
c a r b o n y l a b s o r p t i o n s o f (7t-C H,_)Mn(CO)^, w h i c h occur a t 2110, 2060, 2049 and
3
1950 cm
- 1 274
.
assigned
to v
The absence o f
^in
c
a C=N s t r e t c h i n g frequency
268
Ph C=N-C(Cl)Ph
2
i s noteworthy.
2
and o f t h e d o u b l e t
The p a t t e r n o f
a b s o r p t i o n s due t o t h e l i g a n d i s c o n s i d e r a b l y s i m p l i f i e d i n t h e spectrum o f
the complex.
A p.m.r. spectrum o f Mn(CO)^(Ph CNCPh ), o b t a i n e d i n CDCl
2
accumulating
2
25 times u s i n g a D i g i c o C.A.T., c o n s i s t s o f two m u l t i p l e t s
c e n t r e d a t 2'6 T and 2*9 T, r e l a t i v e t o TMS
Ph C=N-C(Cl)Ph
2
after
3
2
i n CDCl
3
(internal
standard).
shows two s t r o n g m u l t i p l e t s c e n t r e d a t 2*6 T and 3*0
T and a weaker m u l t i p l e t c e n t r e d a t 3'5 T, r e l a t i v e t o TMS
(internal
standard)
The s i g n a l s i n each spectrum were t o o c l o s e t o g e t h e r f o r a s a t i s f a c t o r y
i n t e g r a t i o n t o be o b t a i n e d .
Repeated a t t e m p t s
t o o b t a i n a mass spectrum o f Mn(CO)^(Ph CNCPh ) u s i n g
2
2
-131-
Table
III.l.
I n f r a r e d S p e c t r a o f MnCCO)^ (Ph,,CNCPh ) and Ph C=NC(Cl)Ph
2
Mn(CO) (Ph CNCPh )
4
2
2
2
Ph C=NC(Cl)Ph
-1
cm
Assignment
L
cm ^
2095(w)
2025(s,br)
1938(s)
1919(s,sh)
1595(m)
1575(m)
1493(sh)
1447(sh)
1323(m)
1263(w)
1178
1160
2
(Nujol mull)
268,273
CO
CO
CO
CO
C=N
C=C ( o f a r o m a t i c
C=C
nuclei)
1623(m)
1597(m)
1575(m)
1490(sh)
1449(sh)
1314(w)
1280(m)
1269(m,sh)
1193"
}
Phenyl n u c l e i
(w)
1093(w,sh)
I075(m)
I029(m)
•
'
(w)
I n Plane Bending o f Phenyl
Groups
(m)
l000(vw)
983(w)
957(m)
909(w)
800(m,br)
Out o f Plane Bending
775(m)
762(s)
746(m)
725(w)
698(vs)
693(vs)
667(m)
655(m)
647(w)
626(m)
614(w)
570(m)
730
\,
, . .
C-Cl
724 J C s . s p l i t )
696(vs)
667(m)
637(w)
628(w)
616(w)
600(s)
589(w)
3
Out o f Plane Bending
MCO bend
-132-
t h e d i r e c t i n s e r t i o n probe and v a r y i n g t h e source temperature
from room temperature
to
200°C were u n s u c c e s s f u l .
at insertion
No m e t a l - c o n t a i n i n g
peaks c o u l d be d e t e c t e d , b u t peaks due t o f r a g m e n t a t i o n o f t h e o r g a n i c
were observed.
I n t h e mass spectrum o f Ph2C=N-C(Cl)Ph , no p a r e n t peak i s
2
observed; the. h i g h e s t mass peak i s a t m/e
[Pl^CNCPt^] .
346, c o r r e s p o n d i n g t o
T h i s peak i s n o t , however, observed i n t h e spectrum from
Mn(CO)^(Ph CNCPh ); t h e h i g h e s t i n t e n s e peak was observed a t m/e
2
corresponding
ligand
2
t o [Pt^ON]"^.
The spectrum o f Ph C=N-C(Cl)Ph
2
peak a t m/e 332, c o r r e s p o n d i n g
+
t o [Pt^CCPh,,] .
2
180,
also contains a
T h i s has been a t t r i b u t e d
268
t o an i m p u r i t y , r a t h e r than due t o breakdown o f Ph C=N-C(Cl)Ph , b u t t h e
2
2
peak a l s o occurs i n t h e mass s p e c t r a o f Mn(C0)^(Ph CNCPh ) and i t i s p o s s i b l e
2
t h a t i t a r i s e s from thermal d e c o m p o s i t i o n
2
of t h e complex.
M o l e c u l a r weight d e t e r m i n a t i o n s c o u l d n o t be made on t h e complex s i n c e
i t i s t o o u n s t a b l e i n s o l u t i o n f o r e b u l l i o s c o p i c measurements, and n o t
s o l u b l e enough i n s u i t a b l e s o l v e n t s f o r c r y o s c o p i c measurements.
The i n f o r m a t i o n o b t a i n e d on t h i s complex i s c o n s i s t e n t w i t h t h e
f o r m u l a t i o n Mn(CO)^(Ph CNCPh ).
2
2
The s p e c t r a d a t a on t h e complex, when
compared t o t h a t o f t h e p a r e n t l i g a n d , suggests t h a t t h e phenyl groups i n the
complex a r e a l l i n a s i m i l a r chemical
regarded
environment.
as d o n a t i n g 3 e l e c t r o n s t o t h e m e t a l .
bonding can be envisaged
The l i g a n d can be
Several
types o f m e t a l - l i g a n d
f o r t h i s complex, and some o f then a r e r e p r e s e n t e d
s c h e m a t i c a l l y i n F i g . l i t 8.
-133-
N
Mn
"1-
N
N
Mn
Mn
a)
(b)
(c)
C
Mn
N
N
&
c
Mn
N
Mn
(d)
(e)
x
( f )
Fig.III.8.
The
first
two p o s s i b i l i t i e s , ( a ) and ( b ) , r e p r e s e n t t h e extremes d e s c r i b e d
i n Section A of t h i s chapter, f o r a p s e u d o - a l l y l i c
l i g a n d , w h i l e ( c ) shows
the same arrangement o f atoms i n t h e l i g a n d , b u t the m e t a l , i n t h e same
p l a n e as t h e CNC s k e l e t o n ,
i s between t h e two carbon atoms, i n t e r a c t i n g o n l y
w i t h t h e i t - o r b i t a l s o f t h e l i g a n d , and n o t w i t h t h e n i t r o g e n
a bond forms between t h e two carbon
a s u b s t i t u t e d azirLdine.
lone p a i r . I f
atoms o f t h e l i g a n d , then t h e l i g a n d i s
I n t h i s case, t h e m e t a l would bond o n l y t o t h e
n i t r o g e n and t h e l i g a n d c o u l d f o r m a l l y donate 3 e l e c t r o n s
a- and jt-bonds i n v o l v i n g n i t r o g e n
sp h y b r i d and p
z
t o the m e t a l t h r o u g h
orbitals
respectively.
I n ( e ) , the m e t a l forms a normal cr-bond w i t h one carbon atom, and i n t e r a c t i o n
-134-
between t h e CN double bond and t h e m e t a l a l s o occurs.
w i l l p l a y no p a r t i n M-L bonding.
The n i t r o g e n l o n e p a i r
The p o s s i b i l i t y t h a t t h e CNC s k e l e t o n
may be l i n e a r , w i t h an sp h y b r i d i s e d N atom must be c o n s i d e r e d
(Fig.Ill.8f).
R e l a t i v e t o t h e axes shown, t h e n i t r o g e n l o n e p a i r would occupy a pure p
o r b i t a l , and t h e p^ o r b i t a l s on t h e two carbon and t h e n i t r o g e n atoms would
be a v a i l a b l e f o r f o r m a t i o n o f 3 j t - o r b i t a l s .
Thus, M-L bonding c o u l d occur v i a
d o n a t i o n o f t h e n i t r o g e n l o n e p a i r t o t h e m e t a l , and o v e r l a p o f s u i t a b l e m e t a l
o r b i t a l s w i t h t h e it- o r jt* - o r b i t a l s o f t h e l i g a n d .
A l t h o u g h a d e f i n i t e answer t o t h e problem o f t h e bonding
i n t h e complex
130
Mn(CO) (Ph CNCPh ) (and i n t h e r e l a t e d complex [*-CpMo(CO) (Ph CNCPh )]
4
2
2
2
2
2
)
must a w a i t an X-ray c r y s t a l s t r u c t u r e s t u d y , some o f t h e s t r u c t u r e s b r i e f l y
described
a r e l e s s l i k e l y than o t h e r s . A study o f m o l e c u l a r models o f t h e
2
l i g a n d c o n t a i n i n g an sp o r sp h y b r i d i s e d n i t r o g e n atom show t h a t t h e b u l k y
phenyl groups make t h e n i t r o g e n atom v e r y crowded. A photograph o f a model
2
o f t h e l i g a n d w i t h sp
suggests
hybridised N i s included.
C o n s i d e r a t i o n o f t h e model
t h a t s t r u c t u r e s ( c ) and ( e ) i n F i g . I I I . 8 a r e e x t r e m e l y u n l i k e l y ,
s i n c e t h e phenyl groups would p r e v e n t the m e t a l approaching
near enough f o r bond f o r m a t i o n .
t h e CNC s k e l e t o n
Of t h e o t h e r p o s s i b i l i t i e s , ( b ) and ( d ) have
the m e t a l w e l l removed from t h e phenyl groups, and on s t e r i c grounds anyway,
are perhaps t h e most l i k e l y
structures.
A s t r u c t u r e o f type ( e ) i s p r o b a b l y u n l i k e l y , s i n c e t h e s p e c t r o s c o p i c
evidence
on t h e complex suggests
s i m i l a r chemical environment.
t h a t t h e f o u r p h e n y l groups a r e a l l i n a
S t r u c t u r e s ( a ) - ( f ) i m p l y a C-N bond o r d e r
\
\
sac?;
Si
7
1
-135-
between 1 and 2 and an i n f r a r e d a b s o r p t i o n
due t o t h e d e l o c a l i s e d C-N
- 1 273
would be expected i n t h e r e g i o n 1600 t o 1360 cm .
stretch
Indeed, bands a t
1458 cm * and 1505 cm * i n t h e s p e c t r a o f [ ( j t - C ^ H ^ P d C l l g ^ ^ and
274
(n-C,jHg)Mn(C0)^
r e s p e c t i v e l y have been a t t r i b u t e d t o the d e l o c a l i s e d
C-C
s t r e t c h , and replacement o f C by N seems t o make l i t t l e d i f f e r e n c e t o t h e
273
positions of v
v
and Q_Q-
However, bands i n t h i s r e g i o n o f t h e spectrum
of t h e complex can be a t t r i b u t e d t o the p h e n y l n u c l e i , and unambiguous
assignments are n o t p o s s i b l e .
Several t r a n s i t i o n m e t a l ( n o n - c a r b o n y l ) complexes o f a z i r i d i n e and
275—8
s u b s t i t u t e d a z i r i d i n e s have been r e p o r t e d
infrared absorption
~
and they a l l show a s t r o n g
i n the r e g i o n 850-900 cm *, due t o t h e r i n g
deformation.
There i s no band i n t h i s r e g i o n i n t h e spectrum o f MnCcOj^CPb^CNCPt^), and,
s i n c e t h e band p o s i t i o n i s l i t t l e
275
by c o - o r d i n a t i o n t o t h e m e t a l
a f f e c t e d by s u b s t i t u e n t s i n the r i n g o r
, a s t r u c t u r e o f type ( d ) can p r o b a b l y be
ruled out.
Thus, o f the s t r u c t u r a l types i n d i c a t e d i n F i g . I I I . 8 , ( c ) , ( d ) and ( e )
can perhaps be r u l e d o u t .
the complex i s i n t e r m e d i a t e
I t i s perhaps most l i k e l y t h a t t h e s t r u c t u r e o f
between types ( a ) , ( b ) and ( f ) , w i t h t h e N atom
1-2
of the l i g a n d sp
h y b r i d i s e d , and t h e m e t a l i n t e r a c t i n g w i t h b o t h t h e
n i t r o g e n l o n e p a i r , and t h e j t - o r b i t a l s o f t h e CNC
skeleton.
When t h e r e a c t i o n between ( j t - C p ^ N i and Ph2C=N-C(Cl)Ph was a l l o w e d
2
continue
to
f o r 4 days, a s m a l l amount o f p a l e brown s o l i d was i s o l a t e d and
i d e n t i f i e d as t e t r a p h e n y l e t h y l e n e
by a n a l y t i c a l and i n f r a r e d
spectroscopic
-136-
techniques.
The compound i s w h i t e when pure, b u t i s o f t e n o b t a i n e d
as a p a l e y e l l o w s o l i d .
279 280
'
initially
I t s s l i g h t l y low m e l t i n g p o i n t i n d i c a t e s the
presence o f some i m p u r i t y .
When t h e r e a c t i o n was i n t e r r u p t e d a f t e r
n i c k e l o c e n e was r e c o v e r e d
14 h r s . , some u n r e a c t e d
and a complex i s o l a t e d , f o r which a n a l y t i c a l
data,
t o g e t h e r w i t h t h e o r e t i c a l v a l u e s f o r some n i c k e l complexes, i s shown i n
Table I I I . 2 .
Since n i c k e l and c h l o r i n e were d e t e c t e d i n t h e r e s i d u e i n
each r e a c t i o n , and t h e i n f r a r e d spectrum showed o n l y weak a b s o r p t i o n s , i t
seems t h a t t h e u l t i m a t e p r o d u c t s o f the r e a c t i o n between ( i r - C p ^ N i and
Ph C=N-C(Cl)Ph
2
2
a r e Ph C=CPh and N i C l 2
2
2
However, a complex s e r i e s o f
r e a c t i o n s must occur i n which t h e c y c l o p e n t a d i e n y l groups a r e d i s p l a c e d from
the m e t a l by t h e l i g a n d , o r some d e r i v a t i v e o f t h e l i g a n d , and t h e r e s u l t i n g
complex e l i m i n a t e s Ph C=CPh .
2
2
The l i g a n d i t s e l f c o u l d become a t t a c h e d t o
+
the m e t a l , o r i t c o u l d i o n i s e f i r s t , and t h e cation,Ph C=N-CPh
2
attached t o the metal.
2
become
However, t h e former p o s s i b i l i t y i s perhaps t h e most
l i k e l y and a r e a c t i o n p a t h something l i k e t h e one shown i n t h e e q u a t i o n can
be
envisaged:
ci — — c f
/
^^c>
h\
^ C ^ C C + NiCl
+ N ?
C o - o r d i n a t i o n o f t h e l i g a n d v i a t h e n i t r o g e n l o n e p a i r would w i t h d r a w
from t h e a d j a c e n t carbon atoms and weaken t h e C-Cl bond.
charge
Rupture o f t h i s
bond would be encouraged by t h e p o l a r s o l v e n t CHCl^J l a c k o f r e a c t i o n i n
t o l u e n e may be due t o t h e n o n - p o l a r
nature of t h i s solvent.
-137-
Table I I I . 2 .
%C
76-3,78-6
For N i complex i s o l a t e d
%H
%N
4-9
1-8
%halogen
<1%
(Ph CNCPh ) Ni r e q u i r e s
83-1
5-3
3-7
-
(Ph CNCPh )Ni(Ph C=CPh ) r e q u i r e s
84-6
5-4
1-9
-
[(Ph CNCPh )NiCl]
71-1
4-5
3-2
8-0
2
2
2
2
2
2
2
2
2
2
requires
On warming a t o l u e n e s o l u t i o n o f Ni(CO)^ and Ph C=N-C(Cl)Ph
2
2
to"*40°C,
r a p i d d e c o m p o s i t i o n o f the c a r b o n y l was observed and a deep r e d c o l o u r was
observed.
Since Ni(CO)^ i t s e l f does n o t decompose q u i t e so r a p i d l y ( i n t h e
vapour s t a t e d e c o m p o s i t i o n i s slow a t 100°C), i t i s p o s s i b l e t h a t i n t e r a c t i o n
between t h e l i g a n d and Ni(CO)^ was c a t a l y s i n g
supported by the f a c t t h a t t h e Ph C=NC(Cl)Ph
2
the decomposition.
2
This i s
r e c o v e r e d from t h e r e a c t i o n
m i x t u r e c o n t a i n e d c o n s i d e r a b l e q u a n t i t i e s o f Ph C=CPh , as shown by i n f r a r e d
2
2
s p e c t r o s c o p y - t h e spectrum o f t h e y e l l o w c r y s t a l s o b t a i n e d from t h e r e a c t i o n
i s i d e n t i c a l t o t h a t o b t a i n e d by superimposing the s p e c t r a o f Ph C=N-C(Cl)Ph
2
and Ph C=CPh .
2
2
Thus, i t seems p r o b a b l e t h a t s i m i l a r r e a c t i o n s occur between
Ph C=NC(Cl)Ph
2
i n each case.
2
and N i ( C 0 )
4
and U - C p ) N i , Ph C=CPh b e i n g t h e f i n a l p r o d u c t
2
2
2
I n the case o f t h e c a r b o n y l though, the r e a c t i o n was much
more r a p i d and i t seems t h a t t o t a l decomposition o f Ni(CO)^ o c c u r r e d b e f o r e
all
t h e l i g a n d had r e a c t e d .
2
CHAPTER FOUR
R e a c t i o n s o f the G r i g n a r d D e r i v a t i v e of D i p h e n y l k e t i m i n o
d i p h e n y l m e t h y l c h l o r i d e w i t h T r a n s i t i o n M e t a l Complexes
-138-
A.
Experimental
1.
P r e p a r a t i o n o f the G r i g n a r d
o f Ph C=NC(Cl)Ph,,
2
D i p h e n y l k e t i m i n o d i p h e n y l m e t h y l c h l o r i d e was
d i s s o l v e d i n THF
y e l l o w s o l u t i o n , and a s l i g h t excess o f magnesium t u r n i n g s was
r e a c t i o n occurred
added.
No
u n t i l a few drops o f dibromoethane had been added, and
sometimes warming was
i n c o l o u r was
to give a
a l s o necessary t o i n i t i a t e the r e a c t i o n .
A
darkening
u s u a l l y observed, and on occasions the c o l o u r became v e r y
dark p u r p l e , b u t when almost a l l the magnesium had d i s s o l v e d , the s o l u t i o n
had become v e r y p a l e y e l l o w .
one
t o t h r e e hours.
b e f o r e use.
THF
was
The
The
time taken t o reach t h i s stage v a r i e d
s o l u t i o n was
filtered
from
from the u n d i s s o l v e d magnesium
used as the s o l v e n t s i n c e Ph C=NC(Cl)Ph
2
2
i s only
s l i g h t l y soluble i n ether.
2.
Mn(CO ) Br_4_(Ph CNCPh )MgCl
5
2
2
A s o l u t i o n o f (Ph CNCPh )MgCl was
2
pentacarbonyl
occurred
2
filtered
bromide ( 1 * 1 g., 4 mmoles) i n THF
(20 m l . ) .
No r e a c t i o n
a t room t e m p e r a t u r e over 16 h r s . , b u t a f t e r h e a t i n g a t 80°C o v e r n i g h t ,
a s l i g h t amount o f w h i t e p r e c i p i t a t e had
solution.
i n t o a s o l u t i o n o f manganese
separated
from the darkened y e l l o w
A f t e r removal o f s o l v e n t under vacuum a r e d o i l remained which d i d
n o t y i e l d a s o l i d a f t e r washing w i t h pentane and
extracted w i t h several p o r t i o n s of ether u n t i l
leaving a white s o l i d .
The
toluene.
The
o i l was
the e x t r a c t s were c o l o u r l e s s ,
combined e x t r a c t s again gave a r e d o i l on
removal o f s o l v e n t b u t y e l l o w - o r a n g e n e e d l e - l i k e c r y s t a l s were e v e n t u a l l y
-139-
o b t a i n e d by e x t r a c t i n g w i t h a CHCl^/hexane m i x t u r e , and c o o l i n g t o -20°C.
C a r e f u l adjustment
o f the volumes o f each s o l v e n t was necessary, o t h e r w i s e
an o i l separated o u t .
Warming a CHCl^ s o l u t i o n o f the compound produced a
w h i t e p r e c i p i t a t e w h i c h would n o t r e d i s s o l v e i n c h l o r o f o r m .
The compound
i s f o r m u l a t e d as BrMn(CO) (Ph CNCPh ), on the b a s i s o f a n a l y t i c a l and
4
s p e c t r a l evidence.
14*6%.
2
2
M.Pt. 133-5°C ( d ) . Found: C,60-6; H,3-5; N.2-8; B r ,
Mn H NOBr r e q u i r e s C,60'6; H,3*5; N,2-4; Br,13-57..
3Q
21
I n an a t t e m p t t o e l i m i n a t e HBr from t h e complex, an e t h e r s o l u t i o n was
irradiated
for
30 mins.
Rapid decomposition
t o a w h i t e , non-carbonyl
r e s i d u e o c c u r r e d and no i n t e r m e d i a t e c a r b o n y l complex c o u l d be d e t e c t e d .
3.
Mn(C0) Br + .[(p-CHjCgH, ),,CNCPhjMgCl
5
The method used t o prepare
was
the G r i g n a r d d e r i v a t i v e o f (p-CH_C,H,)„CNCPh„
3 o 4 2
2.
i d e n t i c a l t o that described p r e v i o u s l y f o r the diphenyl d e r i v a t i v e .
Equimolar q u a n t i t i e s o f the G r i g n a r d and Mn(C0)^Br i n THF were a l l o w e d t o
r e a c t a t 75°C o v e r n i g h t , when a dark y e l l o w s o l u t i o n and a l i t t l e
p r e c i p i t a t e were observed.
white
Removal o f s o l v e n t under vacuum and e x t r a c t i o n o f
the brown o i l r e m a i n i n g w i t h c h l o r o f o r m gave a y e l l o w s o l u t i o n , whose
i n f r a r e d spectrum was very s i m i l a r t o t h a t o f BrMn(CO)^(Ph CNCPh ), w i t h
2
2
1
c a r b o n y l a b s o r p t i o n s a t 2105(w), 2 0 3 1 ( s h ) , 2 0 2 5 ( s ) , 1 9 3 8 ( s , b r ) cm" .
Repeated a t t e m p t s t o o b t a i n c r y s t a l s from CHCl^/hexane and from THF/hexane
s o l u t i o n s y i e l d e d o n l y brown o i l s .
On one o c c a s s i o n , a s m a l l amount o f
y e l l o w s o l i d was o b t a i n e d which was t h e r m a l l y u n s t a b l e , even i n t h e s o l i d
s t a t e (on h e a t i n g i n a tube sealed under n i t r o g e n , the s o l i d darkened *V50°C
-140-
and m e l t e d w i t h decomposition «*»75 C) and i n c o n s i s t e n t a n a l y t i c a l d a t a was
obtained.
4.
it-CpMo(C0 ) C 1 + (Ph CNCPh )MgCl
3
2
2
A THF s o l u t i o n o f t h e G r i g n a r d reagent ( 2 mmolar) was f i l t e r e d i n t o a
red
s o l u t i o n o f i t - c y c l o p e n t a d i e n y l m o l y b d e n u m t r i c a r b o n y l c h l o r i d e (0*27 g.,
2 mmoles) i n THF (20 m l . ) and t h e r e a c t i o n f o l l o w e d by i n f r a r e d
spectroscopy.
A f t e r o v e r n i g h t s t i r r i n g a t room t e m p e r a t u r e , much s t a r t i n g m a t e r i a l
remained, b u t a new weak band a t 1880 cm"''" was d e t e c t e d .
s o l u t i o n was heated
A portion of this
f o r s e v e r a l hours a t 70°C, b u t t h e spectrum was
little
changed, and removal o f s o l v e n t l e f t an o i l , which c o u l d n o t be c r y s t a l l i s e d .
The o t h e r p o r t i o n o f t h e s o l u t i o n was i r r a d i a t e d f o r s e v e r a l hours.
Again,
the c a r b o n y l a b s o r p t i o n s due t o s t a r t i n g m a t e r i a l , and t h e band a t 1880 cm"'''
p e r s i s t e d , b u t t h e t a r o b t a i n e d on removal o f s o l v e n t c o u l d n o t be
crystallised.
5.
rt-CpFe(C0) Cl
2
+ (Ph CNCPh )MgCl
2
2
A THF s o l u t i o n o f t h e G r i g n a r d ( 2 mmolar) was f i l t e r e d i n t o a r e d
s o l u t i o n o f n - c y c l o p e n t a d i e n y l i r o n d i c a r b o n y l c h l o r i d e (0*44 g., 2 mmoles) i n
THF (20 m l . ) .
A f t e r s t i r r i n g o v e r n i g h t , no change was observed, b u t removal
of s o l v e n t and e x t r a c t i o n o f t h e o i l y r e s i d u e w i t h CHCl^ gave a r e d s o l u t i o n
whose i n f r a r e d spectrum showed two s t r o n g c a r b o n y l a b s o r p t i o n s , v e r y
s h i f t e d from those o f it-CpFe(C0)-Cl.
Suspecting
slightly
t h a t the c r - a l l y l type o f
complex had formed, a f t e r removal o f s o l v e n t , t h e r e s i d u e was
sublimed.
Only jt-CpFe(C0) Cl c o l l e c t e d on t h e c o l d f i n g e r ( i d e n t i f i e d by i t s i n f r a r e d
9
-141-
spectrum) and an i . r . spectrum o f t h e r e s i d u e showed no c a r b o n y l a b s o r p t i o n s .
The r e a c t i o n was repeated and t h e THF s o l u t i o n r e f l u x e d .
No new c a r b o n y l
a b s o r p t i o n s c o u l d be d e t e c t e d i n t h e i n f r a r e d s p e c t r a o f t h e s o l u t i o n and
a f t e r 6 h r s . , bands due t o jt-CpFeCCO^Cl had disappeared.
A s m a l l amount o f
n o n - c a r b o n y l p r e c i p i t a t e was o b t a i n e d , and t h e s o l u t i o n y i e l d e d an orange
t a r , which, though s o l u b l e i n s e v e r a l s o l v e n t s , c o u l d n o t be induced t o
crystallise.
I n another r e a c t i o n , t h e THF was removed a f t e r o v e r n i g h t
s t i r r i n g , and an e t h e r e x t r a c t was i r r a d i a t e d .
be d e t e c t e d b e f o r e decomposition
6.
No new c a r b o n y l species
could
had o c c u r r e d .
NiC 1 . 2 T H F j M P h C N C P h )MgCl
2
2
R e a c t i o n between equimolar q u a n t i t i e s o f t h e n i c k e l d i c h l o r i d e / T H F
adduct ( d e s c r i b e d i n Chapter I I ) and t h e G r i g n a r d reagent was attempted
s e v e r a l times u s i n g a s i m i l a r r e a c t i o n procedure.
When t h e p a l e y e l l o w THF
s o l u t i o n o f t h e G r i g n a r d was f i l t e r e d i n t o t h e THF suspension o f NiCl .2THF
2
an immediate b r i g h t green c o l o u r was observed.
temperature,
On s t i r r i n g a t room
sometimes t h e c o l o u r p e r s i s t e d and e v e n t u a l l y t h e NiCl .2THF
2
dissolved completely.
On o t h e r occasions,,a. deep y e l l o w c o l o u r developed and
a p r e c i p i t a t e formed.
One one o c c a s i o n , an orange s o l i d was i s o l a t e d , and
on o t h e r o c c a s i o n s , p a l e green s o l i d s were o b t a i n e d , by c o n t i n u o u s
liquid
e x t r a c t i o n w i t h benzene o f t h e s o l i d r e m a i n i n g a f t e r removal o f THF. A l l
these s o l i d s were shown t o c o n t a i n n i c k e l , and a n a l y t i c a l data i n d i c a t e d t h e
presence o f C, H, N and c h l o r i n e , b u t t h e f i g u r e s o b t a i n e d were i n c o n s i s t e n t .
The i n f r a r e d s p e c t r a o f d i f f e r e n t samples
v a r i e d , b u t a l l showed bands
-142-
a t t r i b u t a b l e t o the organo groups.
sensitive.
Reaction
The
compounds were a l l e x t r e m e l y a i r
t o produce a n i c k e l complex c o n t a i n i n g the o r g a n i c
l i g a n d i n some form i s a p p a r e n t l y o c c u r r i n g , b u t r e p r o d u c i b l e r e s u l t s c o u l d
not be
B.
obtained.
R e s u l t s and
Warming a THF
Discussion
s o l u t i o n o f Mn(CO),.Br and
(Ph CNCPh )Mg caused r e a c t i o n t o
2
2
occur w i t h f o r m a t i o n o f the complex BrMn(CO)^(Ph CNCPh ).
JJ
2
compound BrMn(CO)^[(p-CR^CgH^) CNPh J
2
o n l y o b t a i n e d as an o i l .
2
Reaction
w a
The
2
analogous
s detected s p e c t r o s c o p i c a l l y , but
o c c u r r e d between the G r i g n a r d d e r i v a t i v e
and NiCl .2THF, b u t r e p r o d u c i b l e r e s u l t s i n the r e a c t i o n c o u l d n o t
2
achieved.
A t t e m p t s t o i n i t i a t e r e a c t i o n between (Ph CNCPh )MgCl and
2
jt-CpMo(CO) Cl and
3
unsuccessful.
was
rt-CpFe(CO) Cl,
2
b o t h t h e r m a l l y and p h o t o c h e m i c a l l y , were
obtained, but attempts
H e a t i n g and
produced a t a r , which c o u l d n o t be
The
crystals.
2
complex, p o s s i b l y a o"-type
suspected, b u t when the r e a c t i o n was worked up, o n l y s t a r t i n g
m a t e r i a l s were r e c o v e r e d .
N
to i s o l a t e a s o l i d yielded only a
I n the i r o n system, the f o r m a t i o n o f a new
d e r i v a t i v e was
2
I n the molybdenum case, i n d i c a t i o n t h a t some s l i g h t r e a c t i o n
o c c u r r i n g was
tar.
be
i r r a d i a t i o n o f the s o l u t i o n b o t h
crystallised.
complex BrMn(CO)^(Ph CNCPh ) was
2
2
o b t a i n e d as y e l l o w , n e e d l e - l i k e
I n the s o l i d s t a t e , s l i g h t decomposition
f o r s e v e r a l weeks, b u t decomposition
e s p e c i a l l y on warming.
occurs on s t o r i n g under
i n s o l u t i o n i s much more r a p i d ,
I t i s v e r y s o l u b l e i n c h l o r o f o r m , and THF,
fairly
s o l u b l e i n e t h e r , s l i g h t l y s o l u b l e i n t o l u e n e and benzene, and almost i n s o l u b l e
in
pentane.
-143-
I n an a t t e m p t e d
s u b l i m a t i o n o f t h e complex, a t 100-120°C, an orange o i l
appeared on t h e c o l d f i n g e r , which was s o l u b l e i n CHCl^ b u t a s o l u t i o n
spectrum showed no c a r b o n y l a b s o r p t i o n s .
The p a l e y e l l o w r e s i d u e was
almost
i n s o l u b l e i n CHCl^, and i t s i n f r a r e d spectrum showed no c a r b o n y l bands, and
t h e o t h e r a b s o r p t i o n s , m a i n l y i n t h e r e g i o n where phenyl groups absorb, were
weak.
The bands observed i n t h e i n f r a r e d spectrum ( N u j o l m u l l ) o f t h e complex
are l i s t e d i n Table I V . 1 , t o g e t h e r w i t h those o f Ph C=NC(Cl)Ph f o r
2
comparison.
A weak a b s o r p t i o n a t 3226 cm
1
i s assigned
2
t o a N-H
stretching
frequency, and c o n f i r m s t h e presence o f hydrogen on t h e n i t r o g e n .
a b s o r p t i o n a t 1618 cm
1
i s assigned
1
i n Ph C=N-C(Cl)Ph2 a t 1623 c m " ) .
2
t o a C=N s t r e t c h i n g frequency
An
V
( c f . Q-^
The remainder o f t h e spectrum shows
c o n s i d e r a b l e changes i n t h e p o s i t i o n s and numbers o f a b s o r p t i o n s , compared t o
the spectrum o f t h e s t a r t i n g m a t e r i a l .
A h i g h r e s o l u t i o n spectrum o f t h e complex i n CHCl^ shows c a r b o n y l
1
a b s o r p t i o n s a t 2 l 0 4 ( w ) , 2 0 3 5 ( s ) , 2 0 2 0 ( s h ) , 1 9 5 5 ( s ) , 1 9 2 3 ( s ) cm" .
Group
t h e o r e t i c a l t r e a t m e n t s o f Mn(CO)^LX o c t a h e d r a l m o l e c u l e s i n d i c a t e t h a t a
c i s - t e t r a c a r b o n y l complex should have 4 a c t i v e CO s t r e t c h i n g modes i n t h e
i n f r a r e d spectrum ( 3 s t r o n g and 1 weak) w h i l e t h e t r a n s isomer s h o u l d g i v e
,
. 281' 282
r i s e t o o n l y 2 a b s o r p t i o n s ( 1 weak and 1 s t r o n g ) .
'
The c i s - and t r a n s -
t r i c a r b o n y l compounds Mn(CO)^L X should g i v e r i s e t o 3 s t r o n g a b s o r p t i o n s , and
5
283
1 weak and 2 s t r o n g a b s o r p t i o n s , r e s p e c t i v e l y .
Thus t h e s o l u t i o n spectrum
of BrMnCCO^CPt^CNCPt^) i s c o n s i s t e n t w i t h t h e compound b e i n g a t e t r a c a r b o n y l
-144-
Table I V . 1 .
I n f r a r e d S p e c t r a ( N u j o l m u l l ) o f BrMn(CO)^(Ph CNCPh ) and Ph C=NC(Cl)Ph
2
BrMn(CO) (Ph CNCPh )
4
2
2
2
Ph-C=NC(Cl)Ph„
-1
cm
2
Assignment
2
268,273
L
cm ^
3226(w)
2032(s)
2022(s)
1942(s,sh)
1923(s)
N-H
1623(m)
16l8(m)
1600(m)
1580(m)
1486(sh)
1453(sh)
1241(m)
C=N
C=N ?
C=C ( o f a r o m a t i c
C=C
nuclei)
1597(m)
1575(m)
1490(sh)
1449(sh)
1314(w)
1280(m)
1269(m,sh)
1193'
)
Phenyl n u c l e i
1164(m)
1080(m)
1031(w)
(w)
I n Plane Bending o f Phenyl
Groups
(m)
1004(m)
(w)
973(vw)
935(m)
908Qn)
780
(s.split)
772
747(w)
730(s)
701(vs)
694(sh)
649(s)
627(vs)
614(w)
595(s)
570(vw)
527(s)
495(w,br)
Out o f Plane Bending
( s
s
724 | > P
696(vs)
667(m)
637(w)
628(w)
616(w)
600(e)
589(w)
l j L t
C-Cl
>
)
Out o f Plane Bending
MC0 bend
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d e r i v a t i v e w i t h t h e bromide i o n and l i g a n d i n m u t u a l l y c i s p o s i t i o n s .
The
p a t t e r n o f c a r b o n y l a b s o r p t i o n s i n the s o l i d s t a t e d i f f e r s s l i g h t l y
from
t h a t i n the s o l u t i o n ; t h e weak h i g h frequency band has disappeared,
and t h e
shoulder a t 2020 cm ^ i a more r e s o l v e d .
These d i f f e r e n c e s c o u l d be due t o
c r y s t a l packing e f f e c t s i n the s o l i d , o r might suggest a s l i g h t change i n
282
symmetry i n t h e s o l i d
state.
I n t h e f a r - i n f r a r e d spectrum o f the complex, a broad a b s o r p t i o n , c e n t r e d
a t 214 cm ^ i s observed.
A s i m i l a r band i s c e n t r e d a t 216 cm"^" ( l i t .
218
1 284
cm
)
i n t h e spectrum o f Mn(C0),.Br and i s assigned
t o t h e Mn-Br s t r e t c h i n g
284
frequency.
There appear t o be no o t h e r r e p o r t e d t e t r a c a r b o n y l manganese h a l i d e
complexes c o n t a i n i n g n i t r o g e n l i g a n d s .
( T a b l e I . 2 ( i i ) , p. 4 0 ) . R e a c t i o n o f
Mn(C0)^X (X = C l , B r , I ) w i t h amines e.g. py, a n i l i n e , g i v e s t h e d i s u b s t i t u t e d d e r i v a t i v e MhCCO^LjX d i r e c t l y , w i t h no evidence f o r f o r m a t i o n
14
o f Mn(C0)^LX s p e c i e s .
I t i s p o s s i b l e t h a t t h e b u l k y l i g a n d i n t h e complex
B r M ^ C O ^ P l ^ C N C P l ^ ) makes t h e m e t a l s t e r i c a l l y crowded, so t h a t t h e monos u b s t i t u t e d complex i s more s t a b l e than t h e d i s u b s t i t u t e d one would be.
281
T e t r a c a r b o n y l d e r i v a t i v e s c o n t a i n i n g o t h e r l i g a n d s have been prepared
, e.g.
Mn(CO) (PPh )Br.
4
3
A p.m.r. spectrum o f BrMn(CO)^(Ph CNCPh ) i n CDClg ( w i t h TMS as i n t e r n a l
2
2
r e f e r e n c e ) was o b t a i n e d a f t e r 339 accumulations
u s i n g a D i g i c o C.A.T.
spectrum shows a s t r o n g peak a t 2*76 T, w i t h a l i t t l e f i n e
The
structure
d i s c e r n i b l e due t o t h e p r o t o n s i n the. phenyl groups, and a weak peak a t 0*04 T
-146-
due t o t h e hydrogen on t h e n i t r o g e n .
The approximate r a t i o o f peak areas
i s 2 0 : 1 , as r e q u i r e d by t h e complex.
Repeated a t t e m p t s were made t o o b t a i n a mass spectrum o f t h e complex, v i a
t h e d i r e c t i n s e r t i o n probe.
from room t e m p e r a t u r e t o
from 8 eV t o 70 eV.
The source t e m p e r a t u r e a t i n s e r t i o n was v a r i e d
150°C, and t h e a c c e l e r a t i n g v o l t a g e was v a r i e d
I n each case, the o n l y peaks observed were due t o break-
down o f t h e o r g a n i c l i g a n d , and no m e t a l - c o n t a i n i n g fragments c o u l d be
detected.
As i n t h e case o f t h e complex MnCcO^CPt^CNCPl^), t h e h i g h e s t
4-
i n t e n s e peak was observed a t m/e 182, which corresponds t o [PhjCNHg] , a p a r t
from a peak a t m/e 332, c o r r e s p o n d i n g t o [Pl^CCF!^]"*", which may a r i s e from
thermal d e c o m p o s i t i o n o f t h e complex, or be p r e s e n t as an i m p u r i t y .
No
1
peak was observed a t m/e 342, c o r r e s p o n d i n g t o [ Pl^CNCPt^]" ".
M o l e c u l a r w e i g h t d e t e r m i n a t i o n s c o u l d n o t be made on t h e complex, as i t
i s t o o u n s t a b l e i n s o l u t i o n f o r e b u l l i o s c o p i c o r osmometric measurements t o
he made, and n o t s o l u b l e enough i n s u i t a b l e s o l v e n t s f o r c r y o s c o p i c
measurements.
The Mn-Br s t r e t c h i n g f r e q u e n c y i n t h e f a r - i n f r a r e d spectrum c o n f i r m s
t h a t t h e bromine i s a t t a c h e d t o t h e m e t a l r a t h e r t h a n t h e o r g a n i c l i g a n d , and
r u l e s o u t t h e p o s s i b i l i t y t h a t t h e complex i s o f t h e t y p e
H
+
-
[MnCCO^Pt^C-N-CPl^] Br , i n which t h e p o s i t i v e l y charged l i g a n d would be
i s o e l e c t r o n i c w i t h [R C-C-CR ].
7
9
I t seems l i k e l y , t h e n , t h a t t h e l i g a n d i n
t h e complex i s n e u t r a l , d o n a t i n g 2 e l e c t r o n s t o t h e m e t a l .
the hydrogen on t h e n i t r o g e n i s t h o u g h t t o be t h e s o l v e n t .
The source o f
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As f o r MnCCO^Pt^CNCPt^ ) , s e v e r a l types o f m e t a l l i g a n d bonding can be
envisaged f o r BrMnCCO^CPt^CNCPl^) and some o f them a r e r e p r e s e n t e d
schematically i n Fig.IV.1.
x
/
H
H
y
Mn
N
Mn
(a)
Mn
(b)
II
Br
,H
OC
Mn
OC
i\c_>*r
CPh
CPh
Mn
or
OC
Br H
Ph
ft
(c)
(d)
(e)
Fig.IV.1.
The f i r s t p o s s i b i l i t y , ( a ) r e p r e s e n t s
scheme.
a p s e u d o - a l l y l i c type o f bonding
2
The N atom i s sp h y b r i d i s e d , as a r e t h e two C atoms, and these
o r b i t a l s form a-bonds.
The p
o r b i t a l s on each atom ( w i t h r e f e r e n c e
t o the
z
axes drawn) can o v e r l a p t o form ir-bonds, b u t i n t h i s case, t h e p
z
o r b i t a l on
the n i t r o g e n i s o c c u p i e d by 2 e l e c t r o n s and so t h e r e a r e 4 e l e c t r o n s t o
occupy t h e i r - o r b i t a l s o f t h e CNC s k e l e t o n , whereas i n t h e n e u t r a l l i g a n d
(Ph_CNCPh_), o n l y 3 e l e c t r o n s occupy t h e CNC
rt-orbitals.
Some o v e r l a p between
-148-
m e t a l o r b i t a l s and t h e i t - o r b i t a l s c o u l d occur t o g i v e m e t a l - l i g a n d bonding.
Structure ( c ) represents
t h e p o s s i b i l i t y o f bond f o r m a t i o n between t h e two
carbon atoms t o g i v e a s u b s t i t u t e d a z i r i d i n e r i n g .
T h i s would perhaps n o t
285
be u n r e a s o n a b l e , s i n c e Acheson
describes
t h e s y n t h e s i s o f a z i r i d i n e s from
a l k y l o r a r y l magnesium h a l i d e s and k e t i m i n e d e r i v a t i v e s .
Metal-ligand
bonding i n ( c ) i s v i a the n i t r o g e n l o n e p a i r .
S t r u c t u r e s ( d ) and ( e ) a r e s i m i l a r t o t h e c y c l i c a c y l s t r u c t u r e s
0
proposed by K i n g and B i s n e t t e ^ " ^ f o r t h e compounds (CH^ ) NCH CH COMn(CO)^ and
2
NC^H^C^COMnCcO)^.
2
2
2
They suggest t h a t i n i t i a l l y t h e a-complex forms e.g.
(CH ) NCH CH Mn(CO)
3
2
2
5
( f r o m NaMn(CO) and C l C H C H N ( C H ) ) which can then
5
2
2
3
2
undergo an i n t r a m o l e c u l a r rearrangement t o form t h e c y c l i c a c y l d e r i v a t i v e .
A s i m i l a r pathway can be imagined f o r t h e complex BrMn(CO)^(Ph CNCPh ) i . e .
2
Ph C=N-C(Ph >Mn(CO) Br
2
2
°^
>- Ph C
4
2
2
">Mn(CO) Br
3
N
N~CPh!T
H
2
Rearrangement o f t h e s k e l t o n would be r e q u i r e d t o g i v e s t r u c t u r e ( e ) .
S t r u c t u r e ( b ) can p r o b a b l y be r u l e d o u t on s t e r i c grounds, when a model
of the l i g a n d i s studied.
for
S t r u c t u r e s ( a ) and ( c ) a r e b o t h p o s s i b l e , b u t as
t h e complex Mn(CO)^(Ph CNCPh >, no a b s o r p t i o n i n t h e 850-900 r e g i o n , due
2
2
262
to r i n g deformation
, i s observed i n t h e i n f r a r e d spectrum o f
1
BrMn(CO)^(Ph CNCPh ).
2
2
The band a t 1618 cm"
i n t h e spectrum o f t h e complex
has been assigned t o a C=N s t r e t c h i n g frequency.
This i s n o t i n c o n s i s t e n t
w i t h t h e bonding d e s c r i p t i o n g i v e n f o r s t r u c t u r e ( a ) , s i n c e t h e r e a r e 4
-149-
e l e c t r o n s i n t h e j t - o r b i t a l s o f t h e CNC s k e l e t o n and i t i s p o s s i b l e t h a t t h e
CN bond o r d e r w i l l approach 2.
The two a c y l s t r u c t u r e s ( d ) and ( e ) c o u l d a l s o perhaps account
for
t h e band a t 1618 cm \
since the a c y l carbonyl s t r e t c h i n g
frequencies
i n t h e compounds (CH,)-N(CH_)„COMn(CO). and NC H CH C0Mn(C0). occur a t 1660
3 2 2 2
4
5 4 2
4
c
and 1668 cm
, respectively.^"*
/
o
However, t h e p a t t e r n o f c a r b o n y l
a b s o r p t i o n s i n t h e spectrum o f t h e complex d i f f e r s from t h a t expected
c i s - t r i c a r b o n y l manganese complex.
fora
A l s o , t h e 4 phenyl groups i n these two
s t r u c t u r a l types would n o t be e q u i v a l e n t , and t h e p.m.r. spectrum o f
BrMn(CO)^(Ph CNCPh ) shows t h a t they a r e .
2
2
Thus, s t r u c t u r e s o f type ( a ) o r ( c ) seem t h e most l i k e l y f o r t h e
complex BrMn(CO)^(Ph CNCPh ), w i t h s t r u c t u r e ( a ) perhaps t h e most l i k e l y
2
2
possibility.
I n o r d e r t o understand more f u l l y t h e type o f bonding between t h e m e t a l
and l i g a n d i n t h e complex BrMn(CO)^(Ph CNCPh ), t h e p r e p a r a t i o n o f t h e l i g a n d
2
2
Ph C=N-C(H)(CH2) was a t t e m p t e d , i n t h e hope t h a t t h e analogous compound
2
2
BrMn(CO)^(Ph CNC(CH ) ) c o u l d be prepared v i a t h e l i t h i u m d e r i v a t i v e o f t h e
2
ligand.
3
2
The s i m p l i f i e d s p e c t r a o f t h i s complex may have been more r e a d i l y
interpreted.
However, the r e a c t i o n o f Ph C=NLi w i t h (CH.j) CCl, i n
2
2
r e f l u x i n g t o l u e n e , gave a p r e c i p i t a t e o f L i C l b u t no t r a c e o f t h e r e q u i r e d
compound.
I d e a l l y , s t u d i e s o f t h e r e a c t i o n s o f t h e l i g a n d R C=N-C(Cl)R , where R
2
2
i s H, o r a simple a l k y l group w i t h Mn(C0),.Br would have g i v e n s p e c t r a l data
-150-
w h i c h c o u l d p r o b a b l y be e a s i l y i n t e r p r e t e d .
However, t h e r o u t e t o t h i s
l i g a n d i n v o l v e s t h e use o f k e t i m i n o l i t h i u m compounds, and o n l y d i a r y l k e t i m i n e s
were a v a i l a b l e a t t h e time ((t-Bu)2C=NH) has v e r y r e c e n t l y been
i n these
C.
prepared
laboratories^**).
Conclusions
S t u d i e s o f t h e l i g a n d Ph C=N-C(Cl)Ph
2
2
and i t s G r i g n a r d d e r i v a t i v e , w i t h
t r a n s i t i o n m e t a l c a r b o n y l and n o n - c a r b o n y l compounds have y i e l d e d some
interesting results.
Two manganese c a r b o n y l complexes c o u l d be i s o l a t e d
and c h a r a c t e r i s e d , a l t h o u g h b o t h appeared t o decompose r e a d i l y , e s p e c i a l l y
in solution.
I t i s t e n t a t i v e l y proposed t h a t these complexes b o t h c o n t a i n a
p s e u d o - a l l y l i c o r r e l a t e d type o f s t r u c t u r e .
The i n f o r m a t i o n o b t a i n e d on t h e
n i c k e l systems s t u d i e d showed t h a t complex f o r m a t i o n between t h e m e t a l and
some form o f t h e l i g a n d o c c u r r e d , b u t t h a t t h e r e s u l t i n g species were
e x t r e m e l y u n s t a b l e and r a p i d l y decomposed.
was i d e n t i f i e d as one o f t h e decomposition
Attempted
I n one case, t e t r a p h e n y l e t h y l e n e
products.
r e a c t i o n s between t h e l i g a n d and n - c y c l o p e n t a d i e n y l
and i r o n c a r b o n y l h a l i d e s were u n s u c c e s s f u l .
the l a c k o f r e a c t i o n
molybdenum
A possible explanation f o r
between these compounds, (and between Nart-CpMo(CO).j
and Ph2C=N-C(Cl)Ph2) i s t h a t t h e s t e r i c a l l y crowded l i g a n d p r e v e n t s t h e
m e t a l , w i t h i t s b u l k y s u b s t i t u e n t s , from appraoching
f o r m a t i o n t o occur.
rt-CpM(C0) (Ph
9
near enough f o r bond
The e x i s t e n c e o f t h e s t a b l e complexes
CNCPh-)
(M = M o
1 3 0
, W
2 6 1
) i n which t h e l i g a n d i s t h o u g h t t o be
-151-
pseudo a l l y l i c
seems t o c o n t r a d i c t t h i s i d e a .
these d e r i v a t i v e s was
However, the l i g a n d i n
s y n t h e s i s e d " i n s i t u " from 2 moles o f Ph2C=NLi and
i t s g e o m e t r i c a l arrangement i n the complex perhaps d i f f e r s from t h a t i n
the l i g a n d , a l l o w i n g m e t a l - l i g a n d bonding t o occur.
CHAPTER FIVE
Some A z i r i d i n e D e r i v a t i v e s o f T r a n s i t i o n M e t a l Carbonyls
-152-
A.
Introduction
Since one o f t h e p o s s i b l e s t r u c t u r e s o f b o t h t h e complexes
Mn(CO) (Ph CNCPh ) and BrMn(CO) (Ph CNCPh ) i n v o l v e s an a z i r i d i n e r i n g , some
4
2
2
4
2
2
p r e l i m i n a r y s t u d i e s o f a z i r i d i n e l i g a n d s i n m e t a l c a r b o n y l systems were
undertaken.
The aims o f the s t u d y were, f i r s t l y ,
t o see i f a z i r i d i n e
would
form complexes w i t h m e t a l c a r b o n y l s c o n t a i n i n g t h e three-membered r i n g , and
secondly, t o see i f r i n g opening
would
l e a d t o p s e u d o - a l l y l type complexes.
The use o f t e t r a p h e n y l a z i r i d i n e may have g i v e n compounds s i m i l a r t o those
o b t a i n e d from Mn(CO),.Br and Ph C=NC(Cl)Ph , b u t t h i s a z i r i d i n e has been o n l y
2
2
287
t e n t a t i v e l y r e p o r t e d as an i m p u r i t y
and so t h e u n s u b s t i t u t e d a z i r i d i n e ,
e t h y l e n e i m i n e , was s t u d i e d i n i t i a l l y .
E t h y l e n e i m i n e has been r e p o r t e d t o form q u i t e s t a b l e complexes w i t h
275 278
I I I
275
several t r a n s i t i o n metals
~
, e.g. [Co
Az^(N0 ) ]Br
,
2
2
11
[ C r * A z , . H 0 ] C l . j ^ " ' and [ M n ^ A z ^ ] C l . T h e complexes a r e s i m i l a r t o those
2
2
275 276
'
, and t h e s t e r i c p r o p e r t i e s o f e t h y l 2 76
eneimine f a l l between those o f MeNH and EtNH The l i g a n d seems t o
formed by NH^ and p r i m a r y amines
2
2
complex more s t r o n g l y than expected f o r a secondary amine o f comparable
b a s i c i t y , and t h e r i n g i s q u i t e s t a b l e when bonded t o a m e t a l i n a s o l i d
2 76
complex.
However, many u n s u c c e s s f u l a t t e m p t s have been made t o s y n t h e s i s e
complexes w i t h a z i r i d i n e , which a r e w e l l known w i t h o t h e r amines and w i t h
275
pyridine.
Spectroscopy
showed t h a t r i n g cleavage had o c c u r r e d i n these
reactions.
Ring opening o f a z i r i d i n e s i s c a t a l y s e d by a c i d s , which p r o t o n a t e t h e
-153-
n i t r o g e n t o g i v e t h e immonium i o n , and subsequent
a t t a c k by a n u c l e o p h i l e
. . . ,
.
.
288
w i t h simultaneous r i n g opening occurs.
e.g.
R
7\
RRC
2
3
— • CH
+
/\
H
R R^C —
2
2
(Y
If
occur:
—
CH
NHR,
2
= nucleophile)
t h e n u c l e o p h i l e i s an uncharged
will
-> R-R_CCH_Y
2 3, 2
a z i r i d i n e m o l e c u l e , then p o l y m e r i s a t i o n
285
CH CH NH
|
N+
H
H
+N
H
A^
2
0
2
A
0
2
H
0
2
A
polymer
B r a n c h i n g o f t h e polymer can o c c u r , t h e degree o f b r a n c h i n g depending upon
289
the c o n c e n t r a t i o n o f t h e c a t a l y s t ( i . e . t h e a c i d ) and on t h e temperature.
A l t h o u g h r u p t u r e o f a C-N bond u s u a l l y occurs i n r i n g opening, p y r o l y t i c
290
i s o m e r i s a t i o n by r u p t u r e o f t h e C-C bond has been r e p o r t e d
h
P
h
>^y
N
175-205°C»
PhCH=N-CH Ph
2
\
H
P t K
/ C H
A7
Ph' \ /
2
175-205°C
—
*
h
P 2
C = N
-
C H
2
C H
3
, e.g.
-154-
D e r i v a t i v e s and polymers o f a z l r i d i n e s have wide i n d u s t r i a l and
p h a r m a c e u t i c a l a p p l i c a t i o n s , and i n p a r t i c u l a r , some o f t h e t r a n s i t i o n m e t a l
275
complexes a r e p o t e n t i a l agents i n cancer chemotherapy.
S t u d i e s o f e t h y l e n e i m i n e w i t h Mn(CO)^Br and t h e Group V I m e t a l
were undertaken,
s i n c e , besides
carbonyls
t h e p o s s i b l e r e l e v a n c e o f t h e manganese system
t o t h e work d e s c r i b e d i n t h e two p r e v i o u s c h a p t e r s , these c a r b o n y l s a l l form
s t a b l e d e r i v a t i v e s w i t h a v a r i e t y o f amines ( s e e Chapter I ) .
B.
Experimental
1.
Mn(CO) Br + A z i r i d i n e
5
This r e a c t i o n was r e p e a t e d s e v e r a l t i m e s , and was m o n i t o r e d by i n f r a r e d
spectroscopy.
( a ) E t h y l e n e i m i n e (0*2 m l . , 4 mmoles) i n c h l o r o f o r m ( 2 m l . ) was
added t o a s o l u t i o n o f manganese p e n t a c a r b o n y l bromide ( 1 * 1 g., 4 mmoles) i n
c h l o r o f o r m (40 m l . ) .
E f f e r v e s c e n c e o c c u r r e d s l o w l y b u t a f t e r 24 h r s . a t
room t e m p e r a t u r e , an a d d i t i o n a l amount o f e t h y l e n e i m i n e (0*2 m l . , 4 mmoles)
was r e q u i r e d t o complete t h e r e a c t i o n .
The y e l l o w s o l i d o b t a i n e d on removal
o f v o l a t i l e s was r e c r y s t a l l i s e d from CHCl^/hexane t o g i v e y e l l o w c r y s t a l s o f
complex I ( y i e l d , l g . ) .
S u b l i m a t i o n a t 60-80°C, 0*001 mms/hg gave a v e r y
s m a l l amount o f s u b l i m a t e .
The b u l k o f t h e s o l i d d i d n o t sublime and a f t e r
r e c r y s t a l l i s a t i o n , was shown t o be I .
The i n f r a r e d spectrum
M.Pt. 110-112°C.
o f I i n CHCl^, b e f o r e s u b l i m a t i o n showed bands a t
1
2 l 0 5 ( v w ) , 2 0 3 7 ( s ) , 2 0 l 9 ( w , s h ) , 1976(vw) and 1 9 3 1 ( s , b r ) cm" .
After sublimation,
the r e c r y s t a l l i s e d r e s i d u e showed c a r b o n y l a b s o r p t i o n s a t 2 0 3 7 ( s ) , 1 9 3 2 ( s ) ,
-155-
1 9 1 6 ( s , s h ) cm
s o l u t i o n was
.
The
s m a l l amount o f s u b l i m a t e d i s s o l v e d i n CHCl^, b u t t h e
t o o weak t o g i v e a
A n a l y t i c a l d a t a f o r Complex I .
spectrum.
Found, ( b e f o r e s u b l i m a t i o n ) : C,39'9, 37*8;
H,4«0; N.11'6, 10-6; B r , 20*2%;
30*7; H,2«6; N,6'9; B r , 25-7%.
( r e s i d u e , a f t e r s u b l i m a t i o n ) : C,31*9,
M n ( C 0 ) ( C H N ) B r r e q u i r e s C,28'8; H,3'3;
3
2
5
2
N.9-2; Br,26'2%.
( b ) On r e p e t i t i o n o f t h e r e a c t i o n , u s i n g a 2:1 molar r a t i o o f
C H^N:Mn(C0)^Br, r e a c t i o n was
2
was
complete a f t e r 26 h r s .
The
solution
spectrum
s i m i l a r t o t h a t observed f o r I ( b e f o r e s u b l i m a t i o n ) b u t t h e p r e v i o u s l y weak
bands a t 2105,
2019
and 1976
cm~^ were o f g r e a t e r i n t e n s i t y .
60°C, 0'001 mm/hg gave a y e l l o w s u b l i m a t e , I I ,
whose s o l u t i o n
-1
showed a b s o r p t i o n s a t 2 l 0 0 ( m ) , 2020vs), 1 9 7 0 ( s ) c m .
i n the spectrum
Sublimation at
spectrum
Thus the weaker bands
o f I a r e p r o b a b l y due t o I I .
A n a l y t i c a l data f o r complex I I :
C,51'8; H,5*0; Br,26*1%.
( c ) Manganese p e n t a c a r b o n y l bromide (0'3 g., 1*1 mrnoles) was
t r e a t e d w i t h e t h y l e n e i m i n e ( 1 m l . , e x c e s s ) , and immediate v i g o r o u s
e f f e r v e s c e n c e was
observed, w i t h d i s s o l u t i o n o f t h e s o l i d t o g i v e a c l e a r dark
orange s o l u t i o n .
E f f e r v e s c e n c e ceased a f t e r —5 mins. and a f t e r s t i r r i n g f o r
30 mins., hexane (10 m l . ) was
added.
A t a r r y , y e l l o w s o l i d s l o w l y separated
w h i c h , a f t e r washing w i t h hexane, was r e c r y s t a l l i s e d from CHCl^/ether ( Y i e l d ,
0*18 g . ) .
The
s o l u t i o n spectrum
o f the crude p r o d u c t was almost i d e n t i c a l t o
t h a t of I (before s u b l i m a t i o n ) but a f t e r r e c r y s t a l l i s a t i o n , only absorptions
a t 2 0 3 7 ( s ) and 1 9 2 7 ( s , b r ) cm"''" were observed,
and
the main p r o d u c t o f t h e
-156-
r e a c t i o n was
i d e n t i f i e d as I .
However, s u b l i m a t i o n o f t h i s sample ( a t 60
0*001 mms/Hg) gave a l i t t l e s u b l i m a t e , I I I ,
2 0 3 7 ( s ) , 1946
residue I ,
and 1914
was
-
1
( s , s p l i t ) cm " ".
unchanged.
The
C,
w i t h carbonyl absorptions at
spectrum o f the r e c r y s t a l l i s e d
A n a l y t i c a l data f o r complex I .
Found ( b e f o r e s u b l i m a t i o n ) ; C,35'5, 32*9, 36*0; H,4*6, 4'7; N,10'9; Br, 43*3,
25*6%.
Residue a f t e r s u b l i m a t i o n : C,30*5; H,4'4%.
( d ) Manganese p e n t a c a r b o n y l
t o -196°C and
temperature,
bromide (0*83 g., 3 mmoles) was
t r e a t e d w i t h e t h y l e n e i m i n e (2 m l . ) .
On warming t o room
the s o l i d d i s s o l v e d to give a y e l l o w s o l u t i o n ; vigorous
e v o l u t i o n o c c u r r e d and the r e a c t i o n v e s s e l became q u i t e h o t .
orange gum
o b t a i n e d was
powder was
o b t a i n e d , which was
T h i s compound, I V , was
n o t be r e c r y s t a l l i s e d .
cooled
The
gas
dark
s t i r r e d w i t h e t h e r f o r 2 days, when a p a l e y e l l o w
washed w i t h e t h e r and pumped d r y ( Y i e l d , 2*5 g.
i n s o l u b l e i n a l l common o r g a n i c s o l v e n t s and
could
A n a l y t i c a l d a t a f o r complex IV.
Found: C,32'5, 34-3, 33'0; H , 5 ' l , 5*4, 6*0; N , 8 ' l ; Br,43'7, 42*1%.
2.
Mn(C0),.Br +
lithiumaziridine
( a ) A suspension o f l i t h i u m a z i r i d i n e was
Ethyleneimine
and
prepared
(0*16 m l . , 3 mmoles) i n monoglyme (10 m l . ) was
t r e a t e d w i t h n - b u t y l l i t h i u m i n hexane (3 mmoles).
as
follows.
c o o l e d t o -196°C
(MeLi can a l s o be
. 8
used).
On warming t o room temperature
s a l t was
observed, and a f t e r
a w h i t e suspension o f the l i t h i u m
1 h r . , t h i s was
t r e a t e d w i t h a s o l u t i o n of
manganese p e n t a c a r b o n y l bromide (0*75 g., 3 mmoles) i n monoglyme (40 m l . ) .
E f f e r v e s c e n c e o c c u r r e d and a f t e r s e v e r a l h o u r s ,
the q u a n t i t y o f w h i t e
-157-
p r e c i p i t a t e had i n c r e a s e d .
A s o l u t i o n i n f r a r e d spectrum
o f t h e r e a c t i o n medium
showed s e v e r a l a b s o r p t i o n s i n t h e c a r b o n y l r e g i o n , s u g g e s t i n g a m i x t u r e o f
p r o d u c t s b u t a t t e m p t s t o o b t a i n a s o l i d gave o n l y a t a r , and a t t e m p t e d
s e p a r a t i o n o f t h e m i x t u r e by chromatography was u n s u c c e s s f u l .
( b ) I n a r e p e a t o f t h e r e a c t i o n , a f t e r f i l t r a t i o n from t h e w h i t e
p r e c i p i t a t e , t h e s o l u t i o n was r e f l u x e d f o r s e v e r a l h o u r s , when some o f t h e
c a r b o n y l a b s o r p t i o n s i n t h e s o l u t i o n i n f r a r e d spectrum
disappeared.
Filtration,
c o n c e n t r a t i o n o f t h e s o l u t i o n , a d d i t i o n o f e t h e r and c o o l i n g t o -20°C gave
y e l l o w c r y s t a l s which were k e p t c o l d d u r i n g i s o l a t i o n , b u t on f i n a l l y pumping
dry,
they changed t o an o i l . A l l f u r t h e r a t t e m p t s t o o b t a i n a s o l i d were
unsuccessful.
An i n f r a r e d spectrum
o f t h e o i l showed t h e presence o f co-
o r d i n a t e d e t h y l e n e i m i n e , b u t a l s o bands due t o monoglyme.
No r e a c t i o n c o u l d be d e t e c t e d between t h e o i l , and t r i p h e n y l p h o s p h i n e , i n
monoglyme.
3.
Group V I m e t a l c a r b o n y l s + A z i r i d i n e
(a) Cr(CO)
6
+ Aziridine
No r e a c t i o n o c c u r r e d between chromium hexacarbonyl
and e t h y l e n e i m i n e
i n r e f l u x i n g hexane.
Chromium hexacarbonyl
(0*23 g., 1 mmole) was p l a c e d i n a t h i c k - w a l l e d
g l a s s tube and c o o l e d t o -196°C.
the
tube was evacuated,
A f t e r a d d i t i o n o f a z i r i d i n e ( 1 m l . , excess),
s e a l e d , and a l l o w e d t o warm up t o room
temperature.
Some Cr(C0)g d i s s o l v e d t o g i v e a y e l l o w s o l u t i o n , and on warming t o 60-70°C,
almost a l l t h e s o l i d d i s s o l v e d , and t h e c o l o u r darkened.
The tube was sealed
-158-
i n t o a vacuum l i n e system, cooled t o -196 C and opened u s i n g a break s e a l .
The carbon monoxide was c o l l e c t e d and measured (96 c c s . a t N.T.P.,^4 mmoles)
and i t s i d e n t i t y c o n f i r m e d by i n f r a r e d spectroscopy
and mass s p e c t r o m e t r y .
The excess a z i r i d i n e was then vacuum t r a n s f e r r e d w i t h a f l a s k a t -196°C
c o n t a i n i n g d i l . HCl and the tube f i n a l l y removed from the vacuum l i n e and
the dark r e d t a r e x t r a c t e d w i t h c h l o r o f o r m .
R e c r y s t a l l i s a t i o n gave a t a r ,
which on washing w i t h e t h e r , gave a p i n k s o l i d .
spectrum
The CHCl^ s o l u t i o n
infrared
o f t h e crude p r o d u c t showed a b s o r p t i o n s a t 1992 cm ^ ( C r ( C O ) g ) ,
-1
and a t 1 9 8 1 ( s ) , 1 8 7 6 ( s h ) and 1826(m) c m .
spectrum,
I n the s o l i d s t a t e i n f r a r e d
the o n l y sharp bands were t h e c a r b o n y l a b s o r p t i o n s ( a t 1 8 9 8 ( s ) ,
I 8 6 2 ( s h ) and 1818(m) cm ^ ) .
Other bands were broad and weak, b u t t h e r e was no
band a t t r i b u t a b l e t o the r i n g d e f o r m a t i o n o f e t h y l e n e i m i n e .
A n a l y t i c a l data.
Found: C.39'6, 43*7, 42*7; H,5*5, 7*8, 7-1%.
The
compound
d i d n o t m e l t , b u t the c o l o u r p a l e d t o grey on h e a t i n g t o 300°C, i n a sealed
tube.
A f t e r s t o r i n g f o r a few days a t -20°C, t h e compound would n o t r e d i s s o l v e
i n CHC1 .
3
( b ) Mo(CO), + A z i r i d i n e
b
The same r e a c t i o n procedure was used as d e s c r i b e d f o r Cr(CO)g.
When molybdenum hexacarbonyl
(0*66 g., 2*5 mmoles) and excess a z i r i d i n e ( 2 m l . )
were heated a t 100°C f o r s e v e r a l h o u r s , a dark y e l l o w s o l u t i o n was o b t a i n e d ,
which on c o o l i n g , s e t t o a gum.
,
(102 ccs a t NTP,'"4 5 mmoles).
Carbon monoxide was c o l l e c t e d and measured
The gum d i s s o l v e d i n CHCl„ b u t a l l a t t e m p t s
-159-
t o o b t a i n a s o l i d gave a dark y e l l o w t a r .
Washing the t a r w i t h e t h e r f o r
s e v e r a l days gave a s e m i s o l i d , whose i n f r a r e d spectrum showed o n l y weak,
broad a b s o r p t i o n s and no band due
to r i n g deformation.
Carbonyl a b s o r p t i o n s
i n t h e s o l u t i o n spectrum o f t h e crude s o l i d were observed a t 2016(w), 1 8 9 6 ( s ) ,
-1
1 8 6 9 ( s h ) , 1 8 8 1 ( s ) , 1 7 6 7 ( s ) , 1768(sh) c m , b u t a f t e r s t o r i n g f o r s e v e r a l days,
the s e m i s o l i d would n o t r e d i s s o l v e i n CHCl^( c ) W(CO) + A z i r i d i n e
6
H e a t i n g t u n g s t e n hexacarbonyl
(1*6 m l . ) i n a sealed tube a t 110°C
(0*7 g., 2 mmoles) and
aziridine
gave a dark y e l l o w t a r , b u t a l l the
c a r b o n y l d i d n o t r e a c t even a f t e r 3 days.
On opening t h e tube, t h e CO
c o l l e c t e d and measured (30 ccs. , **»1*3 mmoles).
The
gum
was
was
insoluble i n
THF
and e t h e r , b u t gave a y e l l o w s o l u t i o n w i t h CHCl^j showing c a r b o n y l
a b s o r p t i o n s a t 1 9 4 8 ( s ) (W(C0)
1
6
? ) , 1883(m), 1 8 6 2 ( s h ) , 1812(w) cm" .
Attempts
t o o b t a i n a s o l i d from t h e CHCl^ s o l u t i o n y i e l d e d o n l y a t a r .
R e s u l t s and
Discussion
Several new
c a r b o n y l compounds were d e t e c t e d i n r e a c t i o n s o f manganese
p e n t a c a r b o n y l bromide and a z i r i d i n e , b u t f u l l c h a r a c t e r i s a t i o n o f t h e
products
has n o t y e t proved p o s s i b l e , s i n c e r e p e t i t i o n o f the r e a c t i o n even under the
same c o n d i t i o n s gave d i f f e r e n t r e s u l t s , and m i x t u r e s o f p r o d u c t s were u s u a l l y
obtained.
R e a c t i o n between Mn(C0)^Br ( 1 m o l e ) and a z i r i d i n e (2 m o l e s ) gave complex
I as the major p r o d u c t , and another complex I I ,
obtainable only i n small y i e l d ,
-160-
c o u l d be s e p a r a t e d from I by s u b l i m a t i o n .
I n t h e absence o f a s o l v e n t ,
Mn(C0),.Br and excess a z i r i d i n e a g a i n gave complex I as the major p r o d u c t ,
b u t a t h i r d complex I I I ,
c o u l d be sublimed o u t o f t h i s sample o f I .
However,
r e p e t i t i o n o f t h i s r e a c t i o n on a l a r g e r s c a l e gave an i n s o l u b l e p r o d u c t I V .
R e a c t i o n o c c u r r e d between l i t h i u m a z i r i d i n e and Mn(C0),-Br, b u t the
m i x t u r e o f c a r b o n y l species o b t a i n e d c o u l d n o t be s a t i s f a c t o r i l y
separated.
On h e a t i n g a s o l u t i o n o f t h e p r o d u c t s , one o f t h e species d i s a p p e a r e d , b u t
a t t e m p t s t o o b t a i n a s o l i d from the s o l u t i o n gave o n l y an o i l , c o n t a i n i n g
t h e s o l v e n t , and no r e a c t i o n c o u l d be d e t e c t e d between t h i s p r o d u c t and
triphenylphosphine.
When the Group V I m e t a l c a r b o n y l s and excess a z i r i d i n e
were heated i n a sealed t u b e , displacement
o f c a r b o n y l groups o c c u r r e d .
Only i n t h e case o f Cr(C0)g c o u l d a s o l i d be i s o l a t e d , b u t t h i s changed on
s t a n d i n g and has n o t y e t been f u l l y c h a r a c t e r i s e d .
Mo(C0)g and W(C0)g gave
t a r s , which c o u l d n o t be r e c r y s t a l l i s e d .
Complex I i s o b t a i n e d as a y e l l o w , m i c r o c r y s t a l l i n e s o l i d .
I t
decomposes s l o w l y i n a i r over s e v e r a l days, b u t more r a p i d l y i n s o l u t i o n .
R e f l u x i n g a c h l o r o f o r m s o l u t i o n o f I f o r 3 h r s . caused v e r y l i t t l e change i n
t h e s o l u t i o n i n f r a r e d spectrum
o f t h e complex.
On h e a t i n g i n a sealed
I darkened a t 88°C and m e l t e d ( w i t h d e c o m p o s i t i o n )
tube,
a t 110-112°C.
I f e t h y l e n e i m i n e behaves as a normal weak base towards Mn(C0)^Br, then
1
t h e expected p r o d u c t ^
1
o f t h e r e a c t i o n i s Mn(C0)^Az Br.
?
Two moles o f l i g a n d
were r e q u i r e d f o r complete r e a c t i o n o f Mn(C0),.Br ( 1 mole) i n CHCl.^.
i n f r a r e d s o l u t i o n spectrum
The
o f I ( i n CHCl„) shows c a r b o n y l a b s o r p t i o n s a t
-161-
2 0 3 7 ( s ) , 1 9 3 2 ( s ) , 1916(s,sh) cm"
( t h e shoulder i s n o t always r e s o l v e d ) and
t h i s i s t h e expected p a t t e r n f o r an o c t a h e d r a l , c i s - d i s u b s t i t u t e d manganese
283
t r i c a r b o n y l bromide complex
1911 cm ^ i n CHCl^)•
( c f . cis-Mn(C0).jpy2Br, v
The bands i n t h e i n f r a r e d spectrum
a t 2031, 1950,
o f complex I a r e
l i s t e d i n Table V . l , t o g e t h e r w i t h those o f complex I I , and e t h y l e n e i m i n e
itself.
Of p a r t i c u l a r n o t e i s t h e v e r y s t r o n g band a t 884 cm ^ due t o t h e
s y m m e t r i c a l r i n g d e f o r m a t i o n , and t h e N-H s t r e t c h i n g frequency a t 3115 cm ^
( s h o u l d e r a t 3175 cm ^ ) .
to
The l a t t e r i s s h i f t e d t o lower f r e q u e n c y , compared
i t s p o s i t i o n i n e t h y l e n e i m i n e i t s e l f , and t h i s i s c o n s i s t e n t w i t h
e l e c t r o n w i t h d r a w a l from n i t r o g e n v i a t h e cr-bond upon c o - o r d i n a t i o n 32
s i m i l a r s h i f t s have been observed i n m o r p h o l i n e and o t h e r complexes.
of
t h e o t h e r bands i n t h e spectrum
comparison w i t h the spectrum
spectrum
strongly suggests
o f I can be assigned
of ethyleneimine i t s e l f .
Most
t o C l ^ modes, by
Thus, t h e i n f r a r e d
t h a t complex I i s cis-Mn(C0).j(Az ^ B r , i n which t h e
e t h y l e n e i m i n e c o - o r d i n a t e s t o t h e m e t a l v i a t h e n i t r o g e n l o n e p a i r , and t h e
3-membered r i n g s t r u c t u r e o f t h e l i g a n d i s r e t a i n e d i n t h e complex.
The a n a l y t i c a l data o b t a i n e d on two samples o f complex I can be found
i n Section B.l.
The f i g u r e s o b t a i n e d on each sample a r e i n c o n s i s t e n t , b u t
t h e y do suggest t h a t b e f o r e s u b l i m a t i o n , each sample has a h i g h e r carbon and
n i t r o g e n c o n t e n t than Mn(C0),jAz2Br r e q u i r e s .
A f t e r s u b l i m a t i o n , t h e carbon
and n i t r o g e n c o n t e n t o f t h e r e c r y s t a l l i s e d r e s i d u e , I , i s lower.
I a f t e r s u b l i m a t i o n : C,31*0; H,3*5; N,6'9; Br,25*7%.
C,28'8; H,3'3; N,9'2; Br,26'27„).
(Average f o r
Mn(C0) Az Br r e q u i r e s :
3
2
However, t h e f i g u r e s a r e s t i l l n o t i n good
-162-
Table V . l .
I n f r a r e d s p e c t r a o f complexes I and I I ( N u j o l m u l l ) and o f E t h y l e n e i m i n e
(liquid
(cm
CHN
II
I
1
)
3175(sh)
3115(s)
2
- 1
(cm )
3300(m)
3012(w,sh)
2725(w)
2681(vw)
2033(vs)
1912(vs)
1613(vw)
1527(vw)
1447(s)
1353(m)
1344(m)
1264(w)
1232(s)
llll(vw)
1103(m)
1086(s)
1026(w,br)
smear)
5
Assignment.
1
(cm" )
3236(s)
3067(m)
3003(s)
2899(vw)
N-H s t .
N-H s t .
symmetrical
and asymm. s t r e t c h
CO s t .
CO s t .
CO s t .
2092(w)
2000(vs,br)
1946(s)
1536(s)
1451(w)
1311(m)
1261(w)
1190(vw)
1140(s)
1129(s)
I075(vw)
1020(vw)
970(m)
940(m)
890(sh)
884(vs)
804(m,br)
909(m)
881(w)
800(vw,br)
694(s)
641(vs)
719(vw,br)
661(vs)
535(vs)
602(w)
554(w)
CH_ d e f o r m a t i o n
1266(w)
1218(s)
CH t w i s t
ring breathing
1136(w)
CH wag
1089(m)
1021(w)
CH wag and t w i s t
N-<H d e f o r m a t i o n
2
0
2
926(m)
assym. r i n g d e f o r m a t i o n
856(vs)
symm. r i n g d e f o r m a t i o n
785(s)
CH, r o c k
z
MCO bend
MCO bend ?
-163-
agreement w i t h those r e q u i r e d by Mn(C0).jAz2Br and i t i s p o s s i b l e t h a t a l l t h e
i m p u r i t i e s had not been removed, a l t h o u g h the i n f r a r e d s o l u t i o n spectrum o f
t h e r e s i d u e , I , a f t e r s u b l i m a t i o n showed t h a t o n l y one c a r b o n y l species
present.
i s due
was
I t i s n o t known whether the i n c o n s i s t e n c y o f the a n a l y t i c a l data
t o h e t e r o g e n i t y i n the samples, t o u n s a t i s f a c t o r y a n a l y t i c a l
techniques
f o r the type o f compound, or t o p o l y m e r i s a t i o n .
The a n a l y t i c a l d a t a suggests t h a t t h e s u b l i m a t e s I I and I I I o b t a i n e d
I must have a c o m p a r a t i v e l y h i g h carbon and n i t r o g e n c o n t e n t .
o c c a s i o n was
one
s u f f i c i e n t q u a n t i t y o f one o f these species o b t a i n e d f o r
measurements t o be made, and
spectroscopy
Only on
from
t h i s compound ( I I ) i s discussed
later.
Infrared
showed t h a t I I and I I I were b o t h c a r b o n y l complexes, b u t i t i s
p o s s i b l e t h a t the s u b l i m a t e s a l s o c o n t a i n some o r g a n i c polymer formed from
e t h y l e n e i m i n e e i t h e r b e f o r e or a f t e r complex f o r m a t i o n .
Attempts
t o o b t a i n a p.m.r. spectrum o f I w i t h
because o f the f o r m a t i o n o f a p r e c i p i t a t e when TMS
TMS
was
. were u n s u c c e s s f u l ,
added as i n t e r n a l
r e f e r e n c e t o a CDCl^ s o l u t i o n of I , and no peaks were observed i n the spectrum.
The mass s p e c t r a o f t h e complex o b t a i n e d so f a r have n o t shown a p a r e n t peak.
Peaks a t lower m/e
difficult
may
be due
t o breakdown o f Mn(C0).jAz2Br, b u t i t i s
t o make d e f i n i t e assignments s i n c e manganese i s m o n o i s o t o p l c
and
no m e t a s t a b l e peaks were observed.
Of t h e two s u b l i m a t e s o b t a i n e d i n t h e r e a c t i o n s between Mn(C0)^Br and
a z i r i d i n e , the nature of I I I
occasion
i n very small y i e l d .
i s unknown, s i n c e i t was
o n l y i s o l a t e d on
one
I t s i n f r a r e d spectrum i n the c a r b o n y l r e g i o n
i s s i m i l a r t o t h a t o f I , and i s a g a i n c h a r a c t e r i s t i c o f a cis-manganese
-164-
t r i c a r b o n y l bromide d e r i v a t i v e .
On
one o c c a s i o n , s u f f i c i e n t q u a n t i t y o f I I
was
i s o l a t e d t o a l l o w an i n f r a r e d spectrum t o be o b t a i n e d i n the s o l i d
The
s o l u t i o n i n f r a r e d spectrum o f I I ( i n CHCl^) shows c a r b o n y l bands a t
state.
2 l 0 0 ( m ) , 2 0 2 0 ( v s ) , 1970(s) cm~\ and i s c h a r a c t e r i s t i c o f a t r a n s t r i c a r b o n y l
283
manganese bromide d e r i v a t i v e .
The
s o l i d s t a t e spectrum, shown i n Table
V . I d i f f e r s c o n s i d e r a b l y from t h a t o f I ,
In particular, v
N—H
and a l s o from t h a t o f e t h y l e n e i m i n e .
i s s h i f t e d t o h i g h e r f r e q u e n c y , and t h e r e i s o n l y a weak
a b s o r p t i o n i n the 850-900 cm ^ range, where a s t r o n g a b s o r p t i o n due
symmetrical
r i n g d e f o r m a t i o n should occur.
t o the
The a n a l y t i c a l and i n f r a r e d
data
suggest t h a t complex I I i s a t r a n s - t r i c a r b o n y l manganese bromide d e r i v a t i v e
c o n t a i n i n g t h e l i g a n d as a polymer.
peaks t o h i g h m/e
Mass s p e c t r a o f the complex showed
(524) b u t no p a r e n t peak c o u l d be i d e n t i f i e d , and
no
d e f i n i t e assignments made.
I n one r e a c t i o n between Mn(C0),.Br and excess e t h y l e n e i m i n e , i n the
absence o f a s o l v e n t , a l a r g e y i e l d o f a complex, IV was
obtained.
I t seems
t h a t a l l the e t h y l e n e i m i n e must have been used t o form t h e complex, t o
account f o r the y i e l d , and p o l y m e r i s a t i o n o f the l i g a n d must have o c c u r r e d .
A polymeric
f o r m u l a t i o n f o r the compound i s supported by i t s i n s o l u b i l i t y i n
a l l common o r g a n i c s o l v e n t s , and i t s s t a b i l i t y i n a i r .
S u r p r i s i n g l y , the
a n a l y t i c a l d a t a on the complex suggest a h i g h bromine, r a t h e r than a h i g h
carbon c o n t e n t .
The
i n f r a r e d spectrum ( N u j o l mull.) shows s t r o n g c a r b o n y l
a b s o r p t i o n s a t 2024 and 1919
-
( b r o a d ) cm ^ b u t o t h e r a b s o r p t i o n s a r e weak and
broad, and no band a t t r i b u t a b l e t o t h e r i n g d e f o r m a t i o n was
observed.
-165-
When l i t h i u m a z i r i d i n e was r e a c t e d w i t h Mn(CO),-Br, new c a r b o n y l species were
d e t e c t e d , and L i B r was p r o b a b l y e l i m i n a t e d , b u t the m i x t u r e c o u l d n o t be
separated.
Heating
the s o l u t i o n caused some o f t h e c a r b o n y l bands t o
d i s a p p e a r , b u t a t t e m p t s t o i s o l a t e a s o l i d gave o n l y an o i l , c o n t a i n i n g t h e
solvent.
The s o l u t i o n s o f t h e complexes were v e r y a i r - s e n s i t i v e and r e a c t i v e
( t h e y a t t a c k e d t h e KBr p l a t e s used f o r i n f r a r e d s p e c t r o s c o p y ) .
However, no
r e a c t i o n between t h e p r o d u c t r e m a i n i n g a f t e r h e a t i n g and PPh^ was observed,
when an a t t e m p t was made t o produce a more s t a b l e d e r i v a t i v e .
Ring opening o f the l i g a n d o c c u r r e d i n the r e a c t i o n s between t h e Gp.VI
m e t a l c a r b o n y l s and e t h y l e n e i m i n e .
For t h e Mo and W c a r b o n y l s , new c a r b o n y l
d e r i v a t i v e s were d e t e c t e d i n s o l u t i o n b u t o n l y t a r s c o u l d be i s o l a t e d .
A
s o l i d was o b t a i n e d from t h e r e a c t i o n s w i t h Cr(CO)g, b u t t h i s seemed t o change
on s t a n d i n g , and t h e compound c o u l d n o t be f u l l y c h a r a c t e r i s e d .
D.
Conclusions
Reproducible
r e s u l t s were n o t o b t a i n e d i n the r e a c t i o n o f Mn(CO),-Br
w i t h e t h y l e n e i m i n e , a l t h o u g h the main p r o d u c t seems t o be t h e expected d i s u b s t i t u t e d compound, Mn(C0)^Az2Br.
satisfactorily purified.
T h i s complex has n o t y e t been
Other compounds were i s o l a t e d i n s m a l l y i e l d i n
the r e a c t i o n , and one o f these c o n t a i n s the l i g a n d w i t h t h e r i n g opened.
T h i s compound c o u l d form from Mn(C0),jAz2Br, or from r e a c t i o n o f Mn(CO)^Br
w i t h some polymer p r e s e n t i n t h e e t h y l e n e i m i n e i t s e l f .
The former r o u t e i s
p r o b a b l y more l i k e l y , s i n c e i n another r e a c t i o n , e x t e n s i v e p o l y m e r i s a t i o n o f
the l i g a n d o c c u r r e d t o g i v e a d i f f e r e n t p o l y m e r i c compound.
This poly-
-166-
merisation
must have been c a t a l y s e d
f o r the d i f f e r e n c e s
by t h e c a r b o n y l compound, b u t t h e reasons
i n behaviour o f the l i g a n d towards Mn(CO)^Br a r e n o t
clear.
D i r e c t r e a c t i o n o f the Gp.VI m e t a l c a r b o n y l s w i t h some o t h e r amines a l s o
85
produced t a r s .
D e r i v a t i v e s c o n t a i n i n g t h e amine were o b t a i n e d by r e a c t i o n
+
85
o f t h e base w i t h R^N [M(CO),.X] d e r i v a t i v e s (M = Cr, Mo, W)
and t h i s m i g h t
provide a route
t o e t h y l e n e i m i n e d e r i v a t i v e s o f the Gp.VI m e t a l c a r b o n y l s .
CHAPTER SIX
R e a c t i o n s o f N i t r i t e S a l t s w i t h T r a n s i t i o n M e t a l Carbonyls
-167-
A.
Introduction
T h i s c h a p t e r d e s c r i b e s a t t e m p t s t o i n t r o d u c e the n i t r i t e group i n t o
t r a n s i t i o n m e t a l c a r b o n y l systems.
are known, and
Numerous n o n - c a r b o n y l n i t r i t e complexes
+
2[Me^N] 2[Mn(N02)^]
these are u s u a l l y i o n i c e.g.
293
or
294
J
c o n t a i n o t h e r s t r o n g l i g a n d s e.g. N i [ 2 - ( a m i n o m e t h y l ) p i p e r i d i n e ] j C N O g ^
simple n i t r i t e s b e i n g r a r e .
to
the cyanide
The n i t r i t e group i s a s t r o n g l i g a n d c o m i n g near
(
a n i o n i n the s p e c t r o c h e m i c a l s e r i e s and s i n c e t h e r e are
s e v e r a l s t a b l e c a r b o n y l complexes known c o n t a i n i n g the cyanide group, or the
t h i o c y a n a t e and i s o t h i o c y a n a t e groups, t h e r e seemed no reason why
metal n i t r i t e s
should not e x i s t , e s p e c i a l l y , s i n c e the NC^ group possesses j t -
bonding c a p a b i l i t i e s which are o f importance
derivatives.
transition
i n f o r m a t i o n of s t a b l e c a r b o n y l
I t was hoped t o study the n i t r o < — > n i t r i t o isomerism
observed i n non-carbonyl
often
systems, and a l s o t o i n v e s t i g a t e the p o s s i b i l i t y o f
r e d u c i n g the n i t r i t e group t o the n i t r o s y l group w h i l s t c o - o r d i n a t e d t o the
metal.
140
Mn(C0)gN02 had p r e v i o u s l y been prepared
was
and c h a r a c t e r i s e d .
295
'
I t
i s o l a t e d i n s m a l l amounts as a s i d e p r o d u c t i n t h e r e a c t i o n o f
M ^ C C O ) ^ w i t h ^ 0 ^ , t h e main p r o d u c t b e i n g Mn(C0)^N0^.
In addition,
an
i n s o l u b l e , p o l y m e r i c m a t e r i a l o b t a i n e d by the a c t i o n o f m o i s t n i t r i c o x i d e
207
on R u „ ( C 0 ) has been d e s c r i b e d as [Ru(C0) (N0„)„]
on the b a s i s o f
•j
JLZ
Z
z / n
in
i n f r a r e d evidence.
o
Manganese c a r b o n y l compounds were i n v e s t i g a t e d
as Mn(C0)^N02 had a l r e a d y been prepared
initially
and a l s o because maximum s t a b i l i t y
of
-168-
t h e m e t a l c a r b o n y l h a l i d e s i s a t t a i n e d w i t h manganese compounds, and i t seemed
likely
of
B.
t h a t MnCCO),-!^ would be t h e most s t a b l e r e p r e s e n t a t i v e o f t h i s c l a s s
compounds.
Experimental
1.
Mn(CO) Br + NaNO^
5
Sodium n i t r i t e
(0*07 g., 1 mmole) was d i s s o l v e d i n methanol (25 m l . ) and
manganese p e n t a c a r b o n y l bromide (0*32 g., 0*8 mmoles) was added.
s o l u t i o n darkened on s t i r r i n g
The y e l l o w
a t room t e m p e r a t u r e , and a f t e r s e v e r a l h o u r s ,
t h e s o l v e n t was removed under vacuum.
The brown o i l r e m a i n i n g was e x t r a c t e d
w i t h CHC1.J and new c a r b o n y l a b s o r p t i o n s were observed ( a t 2 0 5 1 ( s ) and 1 9 7 0 ( s )
cm •*") b u t a t t e m p t s t o r e c r y s t a l l i s e t h e compound l e a d t o decomposition.
2.
Mn(C0) Br + (Me N)N0
5
(a)
/|
2
Manganese p e n t a c a r b o n y l
bromide (0*2 g., 0*72 mmoles) i n
methanol (15 m l . ) was heated w i t h a methanol s o l u t i o n (20 m l . ) o f t e t r a m e t h y l ammonium n i t r i t e
stirring
( 0 * 1 g., 0*85 mmoles).
a t room temperature
The y e l l o w s o l u t i o n darkened on
and a f t e r s e v e r a l h o u r s , t h e s o l v e n t was removed
under vacuum, and t h e yellow-brown
r e s i d u e e x t r a c t e d w i t h CHCl^.
New
c a r b o n y l a b s o r p t i o n s were d e t e c t e d and a d d i t i o n o f hexane t o t h e CHCl^
s o l u t i o n gave a s m a l l amount o f impure s o l i d , w h i c h had no n i t r i t e
a b s o r p t i o n s i n t h e i n f r a r e d spectrum.
When Mn(C0)^Br and (Me^lOlK^ were r e f l u x e d i n diglyme f o r 4 h r s . , gas
e v o l u t i o n was observed and a brown s o l i d p r e c i p i t a t e d .
F i l t r a t i o n of the hot
s o l u t i o n gave a c o l o u r l e s s f i l t r a t e and t h e r e s i d u e c o n t a i n e d no c a r b o n y l
s p e c i e s , as d e t e r m i n e d
by i . r .
spectroscopy.
-169-
3.
Mn(CO) Br + AgNO^
5
Manganese p e n t a c a r b o n y l
bromide (0*2 g. , 0*72 mmoles) i n THF (20 m l . ) was
heated w i t h excess s i l v e r n i t r i t e .
p r o t e c t e d from the l i g h t ,
of
The
A f t e r s t i r r i n g o v e r n i g h t a t room
temperature,
no change was observed, b u t f i l t r a t i o n and removal
s o l v e n t gave a yellow-orange
s o l i d , contaminated
w i t h black p a r t i c l e s .
s o l i d was r e c r y s t a l l i s e d t w i c e from CHCl^/hexane, but y i e l d e d a m i x t u r e o f
y e l l o w and b l a c k s o l i d s .
The y e l l o w s o l i d decomposed t o t h e b l a c k
solid,
even a t -20°C.
R e p e t i t i o n o f t h e r e a c t i o n i n the more i n e r t s o l v e n t , t o l u e n e gave t h e
same contaminated
p r o d u c t , but a l l a t t e m p t s t o o b t a i n a pure sample o f t h e
y e l l o w compound, by r e c r y s t a l l i s a t i o n from t o l u e n e , CHCl^, o r e t h e r , were
u n s u c c e s s f u l , and attempted
4.
s u b l i m a t i o n caused r a p i d
it-CpFe(C0) X + AgN0
2
2
decomposition.
(X = C l , I )
No r e a c t i o n o c c u r r e d between jr-CpFe(C0) Cl and AgN0
2
Silver n i t r i t e
2
i n water.
(0*38 g., 2*5 mmoles) was added t o a dark y e l l o w - b l a c k THF
s o l u t i o n (20 m l . ) o f j t - c y c l o p e n t a d i e n y l i r o n d i c a r b o n y l i o d i d e (0*3 g., 1 mmole)
and
the suspension s t i r r e d f o r 14 h r s . i n darkness.
and a f t e r f i l t r a t i o n
No change was o b s e r v e d ,
the r e s i d u e was shown t o be a n o n - c a r b o n y l compound ( b y
i n f r a r e d spectroscopy).
Removal o f v o l a t i l e s from t h e orange-brown f i l t r a t e
gave a b l a c k t a r , which on e x t r a c t i o n w i t h e t h e r , gave an orange brown s o l i d ,
contaminated
pet.
w i t h black p a r t i c l e s .
R e c r y s t a l l i s a t i o n from CHCl_ o r t o l u e n e
e t h e r m i x t u r e s gave a b l a c k powder and orange c r y s t a l s .
Attempted
s u b l i m a t i o n ( a t room t e m p e r a t u r e ) , 0*001 mms/Hg onto a c o l d f i n g e r a t -78°C)
-170-
gave no s u b l i m a t e and caused t h e orange c r y s t a l s t o t u r n b l a c k .
R e p e t i t i o n o f the r e a c t i o n i n t o l u e n e gave the same orange p r o d u c t ,
contaminated
w i t h b l a c k p a r t i c l e s , but i n f r a r e d spectroscopy
presence o f a c a r b o n y l n i t r i t e compound, as w e l l as
c a r b o n y l species were separated by chromatography.
alumina;
suggested the
rt-CpFeCCO^I.
The
(Grade I I a c i d Woelm
However, on removal of s o l v e n t from the
s o l u t i o n , a d a r k e n i n g i n c o l o u r was
contaminated
latter
observed, and the y e l l o w s o l i d
w i t h black p a r t i c l e s .
When t h e p r o d u c t was
obtained
chromatographed
a second t i m e , some dark s o l i d remained a t the t o p o f the column and
of
two
e l u t i o n w i t h ( i ) 5:1 CHCl^ihexane gave m a i n l y j t - C p F e ^ O ^ I , ( i i )
CHCl^ gave t h e p r o d u c t ) .
was
still
s o l v e n t from the s o l u t i o n a t 0°C
still
removal
gave an impure p r o d u c t .
A d d i t i o n o f t r i p h e n y l p h o s p h i n e t o a t o l u e n e s o l u t i o n o f the p r o d u c t ,
i n an a t t e m p t t o produce a more s t a b l e d e r i v a t i v e , caused e x t e n s i v e
decomposition.
Attempts were made t o f o r c e the r e a c t i o n between j f - C p F e ^ O ^ I
and AgN©2 t o go t o c o m p l e t i o n .
rt-CpFe^O^I
After s t i r r i n g
a toluene s o l u t i o n of
and AglTC^ f o r 14 h r s . , t h e suspension was
f i l t r a t e heated w i t h another p o r t i o n o f AgN0 2
f i l t e r e d and
the
R e p e t i t i o n o f t h i s procedure
gave no i n c r e a s e i n y i e l d of t h e p r o d u c t , and a s m a l l amount of n - C p F e ^ O ^ I
remained i n s o l u t i o n .
5.
[Rh(C0) Cl]
2
2
+ Ba(N0 )
2
2
and AgN0
2
No r e a c t i o n o c c u r r e d between rhodium d i c a r b o n y l c h l o r i d e dimer and
n i t r i t e , nor between t h e c a r b o n y l and s i l v e r n i t r i t e , i n t o l u e n e a t room
temperature.
barium
-171-
6.
Group V I m e t a l c a r b o n y l s + (Me^N)NO,,
(a)
No r e a c t i o n o c c u r r e d between chromium h e x a c a r b o n y l and
tetra-
m e t h y l ammonium n i t r i t e i n r e f l u x i n g diglyme over 14 h r s .
(b)
A diglyme s o l u t i o n (60 m l . ) o f molybdenum hexacarbonyl (3*5 g. ,
1*3 mmoles) and tetramethylammonium n i t r i t e (1*4 g., 1 mmole) was heated a t
110-120°C f o r 5 h r s .
colour.
Gas
e v o l u t i o n was observed and t h e m i x t u r e darkened i n
F i l t r a t i o n o f t h e h o t s o l u t i o n gave a non-carbonyl r e s i d u e (as shown
by i n f r a r e d s p e c t r o s c o p y ) , b u t a d d i t i o n o f p e t r o l e u m e t h e r (40-60°, 160
to
the c o o l e d f i l t r a t e gave a b l a c k t a r . E x t r a c t i o n o f t h i s t a r w i t h
f i l t r a t i o n and removal o f s o l v e n t gave a brown s o l i d which was
ml.)
THF,
recrystallised
f r o m m e t h a n o l / e t h e r , t o g i v e an orange powder, whose i n f r a r e d spectrum showed
c a r b o n y l a b s o r p t i o n s . A n a l y t i c a l d a t a on d i f f e r e n t samples o f t h i s complex:
C,25-l, 26*6, 21*2; H,3*9, 4*9, 4-0; N,5'4, 6*7, 5'5%.
( c ) R e a c t i o n between t u n g s t e n hexacarbonyl and
n i t r i t e i n d i g l y m e , a t 80°C f o r 3 h r s . , produced
b l a c k s o l i d , which was
tetramethylammonium
t o t a l decomposition t o a
i n s o l u b l e i n a l l common o r g a n i c s o l v e n t s , or i n w a t e r ,
and whose i n f r a r e d spectrum showed no a b s o r p t i o n s due t o CO or N0£ groups.
R e s u l t s and D i s c u s s i o n
S e v e r a l m e t a l c a r b o n y l systems have been s t u d i e d i n a t t e m p t s t o i s o l a t e
t r a n s i t i o n metal carbonyl n i t r i t e d e r i v a t i v e s .
I n the r e a c t i o n s o f Mn(C0),.Br
w i t h n i t r i t e s a l t s , new c a r b o n y l species were d e t e c t e d i n s o l u t i o n b u t
a t t e m p t s t o o b t a i n a s o l i d from the s o l u t i o n s caused d e c o m p o s i t i o n o f the
c a r b o n y l compound.
A y e l l o w p r o d u c t from the r e a c t i o n between Mn(C0) Br
and
-172-
AgN02 was
i s o l a t e d , b u t was
always contaminated
product.
No
detected i n these r e a c t i o n s .
MnCCO^NC^ was
s c o p y showed t h a t i r - C p F e ( C O ) I and A g N 0
2
was
separated
from
i n s o l u t i o n and
decomposition
Ba(NO)
the iodide
by
i n the s o l i d
products.
No
i t s black
s t a t e and
reaction
2
Infrared
2
spectro-
and
2
t h e compound was
c o u l d n e v e r be
occurred
6
decomposition
g a v e some i t - C p F e ( C O ) ( N 0 ) w h i c h
2
chromatography, but
or AgN0 , nor between C r ( C O )
2
with
i s o l a t e d free of i t s
between [ R h ( C O ) C l ]
2
(Me^N)N0 .
and
2
However, (Me^N)N0
2
r e a c t e d w i t h Mo(CO)g t o g i v e a c a r b o n y l p r o d u c t , b u t w i t h W(CO)g,
decomposition
to a grey,
c a r b o n y l or n i t r i t e
The
product
insoluble material
from
i n CHCl^ s o l u t i o n .
(v
2059 a n d
the r e a c t i o n
cm
1
state
) ,
1
The
fill1
that the N0
b u t no
slightly
2
295
, v .
O T
and
840
higher
frequencies
no
a t 1388,
1
cm" ).
further information
and
817
cm
Thus, the product
c o u l d be
than
the
group.
The
at
bands i n t h e
i n Table VI.1 together
a t 1341,
-1
.
two
spectrum,
group i s more e f f i c i e n t
with
s i m i l a r to that
1266
complexes are assigned
1327
showed
2
t h a n jt-CpFe(CO)„Cl ( v
spectrum o f t h e complex i s v e r y
absorptions
AgN0
i n the i n f r a r e d
than i s the c h l o r i d e
by c o m p a r i s o n w i t h o t h e r n i t r i t e
o
1
are at higher
suggesting
2
1170
2028 cm
and
i r - C p F e ( C O ) C l , a p a r t f r o m new
1270,
and
spectrum ( N u j o l m u l l ) are l i s t e d
assignments.
Mn(C0),.N0
2
2008 c m " )
removing charge from the metal
solid
total
occurred, which contained
b e t w e e n j t - C p F e ( C O ) I and
These a b s o r p t i o n s
2047 and
2018
2
groups.
s t r o n g c a r b o n y l a b s o r p t i o n s a t 2071
iodide
unstablt
and
818
cm
t o the N0
[Ru(C0)„(N0 )J
i f b e l i e v e d t o be
- 1
,
of
which,
group
2
207
o
(e.g
, v„„
at
ir-CpFe(CO) N0
obtained, since the i n s t a b i l i t y
2
of
the
2
-173-
compound p r e v e n t e d i t s p u r i f i c a t i o n .
Table
Infrared
VI.1.
s p e c t r u m ( N u j o l m u l l ) o f it-CpFe(CQ) N0
o
Position
-1
cm
Position
-1
cm
Assignment
3062(w)
it-C H
2057(s)
.
.
296
Assignment
853 ( m )
rt-C H -M
CO
835(w)
it-C H -M
2015(s)
CO
818(s)
N0
I426(w)
rt-C H -M
614(s)
it-C H -M
1341(s)
N0
2
596(sh)
it-C H -M
1266(m)
N0
2
588(ms)
n-C H -M
1099(w)
Jt-C H -M
546(ms)
Jt-C^-M
I066(w)
it-C H -M
532(m)
n-C H -M
1003(w)
Jt-C H,.-M
5 5
5
5
5
5
5
5
5
5
5
5
5
5
2
5
5
5
5
5
5
5
5
C
I n t h e r e a c t i o n s o f Mn(C0),-Br w i t h N a N 0 , new c a r b o n y l s p e c i e s w e r e
2
d e t e c t e d i n s o l u t i o n , b u t a l l a t t e m p t s t o i s o l a t e them l e a d t o d e c o m p o s i t i o n .
It
i s possible that
t h e s p e c i e s formed were sodium s a l t s , w i t h
solvent
297
molecules c o - o r d i n a t e d t o the c a t i o n . Farona
a l k a l i metal s a l t s i n methanol
reports
that reaction of
o r d i g l y m e w i t h Mn(C0)^Br l e a d
t o solvent
298
insertion
t o give
salts.
Abel and co-workers
found t h a t
o c c u r r e d w i t h Group V I m e t a l c a r b o n y l s , b u t a l l e f f o r t s
s a l t s caused d e c o m p o s i t i o n .
similar
t o obtain
These-authors r e p o r t , however, t h a t
(Y = h a l o g e n , R = a l k y l ) w i t h Mn(C0),.X compounds ( X = h a l o g e n )
according
t o the equation:
reactions
crystalline
(R^N)Y
react
salts
-174-
+
Mn(CO) X + R.N Y~
5
f
+
diglyme^
o
R N [Mn(CO),XY]~
n
1 2 Q
No e v i d e n c e c o u l d be o b t a i n e d f o r a n a l o g o u s b e h a v i o u r
carbonyl
species
d e r i v a t i v e s o f metal
carbonyls,
18
2
derivatives of
-
and Fe(CO) .
5
cm"
1
and a band a t 1 7 1 7 ( s ) c m
h a s v„ a t 1713 cm
NO
-1
n
2046(s),
1990(sh),
1
1
This
2
t o v„. ( M n ( C 0 ) _ ( N 0 ) ( P P h _ )
NO
3
3
isolated
s p e c t r u m showed c a r b o n y l a b s o r p t i o n s a t 2 0 5 8 ( s h ) ,
1 9 6 1 ( s h ) and 1 9 4 2 ( s ) cm"
2 <
1
and a l s o bands a t 1266(m) and
However, t h e r e were s e v e r a l o t h e r bands i n
r e g i o n o f t h e s p e c t r u m , w h i c h c o u l d n o t be a s s i g n e d , a n d
the nature o f t h i s unstable product
[Rh(CO) Cl]
, attributable
r e g i o n o f t h e spectrum o f t h e impure s o l i d
8 0 l ( m s ) , p o s s i b l y due t o N 0
t h e 1550-600 cm
- 1
1980 a n d 1 9 6 1 ( m s ,
-1
, v„„ a t 2 0 3 4 , 1 9 7 1 , 1926 cm
) . H o w e v e r , no b a n d was
CO
o b s e r v e d i n t h e 1 7 0 0 cm
thereaction.
I n the
a s o l u t i o n spectrum o f t h e crude m i x t u r e i n
showed c a r b o n y l b a n d s a t 2063 a n d 2049 ( s , s p l i t ) ,
3
metal
[ C o ( C 0 ) ^ ] ~ a n d NO,,
e . g . CoCNOXCO)^ f r o m
3
split)
from
2
nitrosyl
a c e t i c a c i d , and [Fe(NO)(CO) ]~ from n i t r i t e s
r e a c t i o n o f Mn(CO),-Br w i t h A g N 0
CHCl
f o r Y = N 0 , and no
c o u l d be i s o l a t e d , f r o m t h i s r e a c t i o n .
The n i t r i t e i o n h a s b e e n u s e d t o p r e p a r e
and
X, Y = C l , B r , I
«
2
i s unknown.
r e a c t s w i t h AgNO^, A g S 0 ^ a n d AgSCN t o g i v e b i n u c l e a r
2
216
complexes c o n t a i n i n g l i g a n d b r i d g e s
, a l t h o u g h AgCN a n d AgF do n o t r e a c t .
No r e a c t i o n c o u l d be d e t e c t e d b e t w e e n t h e c a r b o n y l a n d e i t h e r A g N 0 o r
2
Ba(N0 )
2
under s i m i l a r c o n d i t i o n s .
2
The d i f f e r e n c e i n r e a c t i v i t y
(Me^N)N0
2
i ssurprising,
since
o f t h e Gp.VI m e t a l
hexacarbonyls
+
t h e y a l l r e a c t w i t h R^N X
salts
towards
t o give
-175-
R,N [ M ( C O ) X ] ( X = h a l o g e n )
298
A new c a r b o n y l
c
o n l y i n t h e r e a c t i o n o f Mo(CO)g w i t h (Me^lONC^.
properties of a salt
compound
c o u l d be i s o l a t e d
The p r o d u c t
had t h e
( s o l u b l e i n a c e t o n e , 1^0, MeOH, EtOH, d i g l y m e , THF,
CH^NC^; i n s o l u b l e i n h y d r o c a r b o n s , t o l u e n e , PhNOg, e t h e r ) a n d i t s i o n i c
nature
in
was c o n f i r m e d
by a c o n d u c t i v i t y measurement
10 m l . a c e t o n i t r i l e
solvent
infrared
itself,
gave a r e a d i n g
-4
o f 4*3 x 10
mhos, c o m p a r e d t o t h e
w h i c h h a d a c o n d u c t i v i t y o f 7*2 x 10
spectrum o f t h e s o l i d
2016(s,broad), 1932(sh),
( N u j o l m u l l ) showed c a r b o n y l
absorptions a t
1
+
2
a n d b a n d s a t 1 4 8 8 ( s h ) and 9 5 2 ( m ) , due t o Me^N .
a d d i t i o n , t h e r e were s t r o n g a b s o r p t i o n s
due t o a n i t r o s y l
mhos ) . The
1908 a n d 1 9 8 7 ( s , s p l i t ) c m " , bands a t 1 2 6 6 ( s ) a n d
8 0 0 ( s ) , p o s s i b l y due t o N 0
In
( 0 * 0 0 5 g. o f t h e compound,
s t r e t c h i n g frequency,
a t 1748 a n d 1626 cm \
possibly
b u t s e v e r a l u n a s s i g n e d bands
a p p e a r e d i n t h e s p e c t r u m , a n d no m e a n i n g f u l i n t e r p r e t a t i o n o f t h e d a t a o n
t h i s compound
has been p o s s i b l e .
Conclusions
In
detected
most o f t h e m e t a l c a r b o n y l
i n s o l u t i o n , b u t attempts
decomposition.
too unstable
I n other
t o be f u l l y
nitrite
s y s t e m s s t u d i e d , new s p e c i e s w e r e
t o i s o l a t e compounds
c a s e s , new compounds
characterised.
c o u l d be i s o l a t e d , b u t w e r e
A t l e a s t one o f t h e s e
rt-CpFeCcO^NOg
c o u l d be c h a r a c t e r i s e d a s a n i t r i t e
spectroscopy.
Some i n d i c a t i o n o f t h e f o r m a t i o n
derivatives
often lead t o
i n some o f t h e r e a c t i o n s , was
d e r i v a t i v e , by i n f r a r e d
of nitrosyl
obtained.
compounds,
carbonyl
(i)
Appendix
1
E x p e r i m e n t a l D e t a i l s and S t a r t i n g M a t e r i a l s
M o s t o f t h e r e a c t i o n s d e s c r i b e d w e r e c a r r i e d o u t i n an a t m o s p h e r e o f
pure, d r y n i t r o g e n e i t h e r
Air
i n two-necked
f l a s k s or i n double Schlenk
tubes.
s e n s i t i v e m a t e r i a l s were h a n d l e d i n a Glove Box, o r i f i n s o l u t i o n ,
were t r a n s f e r r e d
f r o m one v e s s e l t o a n o t h e r
by s y r i n g e a g a i n s t a counter
current of nitrogen.
Nitrogen
Supply
"White Spot" n i t r o g e n d i r e c t
f r o m t h e c y l i n d e r was d r i e d b y p a s s a g e
t h r o u g h a t r a p m a i n t a i n e d a t -196°C a n d d e l i v e r e d
system.
A constant pressure
c o n n e c t i n g one o u t l e t
to a multiple
outlet
o f n i t r o g e n was m a i n t a i n e d i n t h e s y s t e m b y
t o an o i l b u b b l e r .
G l o v e Box
The n i t r o g e n a t m o s p h e r e
recycling
i n t h e G l o v e Box was p u r i f i e d
i t t h r o u g h a t r a p a t -196°C, t h r o u g h t w o f u r n a c e s a t 400°C,
c o n t a i n i n g copper w i r e and back
Bench n i t r o g e n was u s e d , a f t e r
transfer
by c o n t i n u o u s l y
tube.
A l l external
t o t h e box v i a a second
passage t h r o u g h t h i s
by t h i s
system, t o f l u s h o u t t h e
t u b i n g was o f c o p p e r o r g l a s s , a n d t h e g l o v e s
u s e d w e r e made o f " B u t a s o l " r u b b e r .
was m a i n t a i n e d
t r a p a t -196°C.
system.
An oxygen
l e v e l o f l e s s t h a n 50 p.p.m.
(ii)
Solvents
Solvents
w e r e u s u a l l y d e g a s s e d o n t h e vacuum l i n e b e f o r e
c a r b o n s o l v e n t s were d r i e d o v e r s o d i u m w i r e .
s t o r e d over C a C l
2
and d i s t i l l e d
from CaCl
and THF w e r e u s e d f r e s h l y d i s t i l l e d
Starting
2
Chloroform
use.
and d i g l y m e
o r P ^5 b e f o r e
2
under n i t r o g e n from
use.
were
Monoglyme
LiAlH^.
Materials
The m a j o r i t y o f t r a n s i t i o n m e t a l d e r i v a t i v e s u s e d as s t a r t i n g
a r e r e a d i l y a v a i l a b l e by methods
Mn(CO) Br, r e f . 2 7 2 ,
5
using
Hydro-
t h e methods
described
( P h P ) N i C l , ref.257.
3
2
2
i n the l i t e r a t u r e ,
materials
i n t h e l i t e r a t u r e , e.g.
The l i g a n d s u s e d w e r e made
e.g. P h C = N C ( C l ) P h ,
2
2
ref.268.
C o m m e r c i a l e t h y l e n e i m i n e ( f r o m K o c h - L i g h t L a b o r a t o r i e s ) was s t o r e d o v e r NaOH
pellets,
t o prevent
p o l y m e r i s a t i o n and used w i t h o u t f u r t h e r
T e t r a m e t h y l a m m o n i u m n i t r i t e was p r e p a r e d f r o m Me^NBr a n d K N 0
pumping a t
o
50 C f o r s e v e r a l
hours.
purification.
2
and d r i e d by
(iii)
Appendix 2
Instrumentation
Infrared
Spectra
Infrared
s p e c t r a i n t h e r a n g e 2*5-25 m i c r o n s
were u s u a l l y r e c o r d e d on
a S p e c t r o m a s t e r , a l t h o u g h a G r u b b - P a r s o n s GS2A p r i s m g r a t i n g
was
spectrophotomer
sometimes used.
Spectra
of solid
between KBr p l a t e s ,
Liquid
samples were r e c o r d e d i n t h e f o r m o f N u j o l
mulls
t h e s a m p l e s b e i n g made up i n t h e G l o v e Box.
samples ( g e n e r a l l y s o l u t i o n s ) were i n s e r t e d
into a solution
cell
( t h i c k n e s s 0 * 1 mm) b y s y r i n g e a n d g a s p h a s e s a m p l e s w e r e r e c o r d e d u s i n g a
10 cm. c e l l .
B o t h c e l l s h a d KBr w i n d o w s , a l t h o u g h CaF2 w i n d o w s w e r e
t i m e s used f o r t h e s o l u t i o n
Far
Infrared
Far
cell.
Spectra
infrared
s p e c t r a ( 2 1 - 5 0 f i ) w e r e r e c o r d e d as N u j o l m u l l s b e t w e e n C s l
p l a t e s u s i n g a G r u b b - P a r s o n s DM2/DB3 p r i s m g r a t i n g
Nuclear
M a g n e t i c Resonance
Nuclear
Spectra
o p e r a t i n g a t 60 Mc/sec.
using tetramethylsilane
under
spectrophotometer.
m a g n e t i c resonance s p e c t r a were r e c o r d e d
spectrometer,
were f i l l e d
some-
o n a P e r k i n - E l x n e r RIO
Samples w e r e u s u a l l y i n CDCl^
(T.M.S.) a s i n t e r n a l r e f e r e n c e .
The s a m p l e
by s y r i n g e a g a i n s t c o u n t e r c u r r e n t n i t r o g e n , and were
nitrogen.
solution,
tubes
sealed
(iv)
Mass
Spectra
Mass s p e c t r a w e r e r e c o r d e d on a n A . E . I . MS9 mass s p e c t r o m e t e r a t 70 eV
and
an a c c e l e r a t i n g p o t e n t i a l
and
300°C, a n d e l e c t r o m a g n e t i c s c a n n i n g .
direct insertion
of 8 kv, with
i n t o t h e i o n source.
a source
t e m p e r a t u r e b e t w e e n 60
Compounds w e r e i n t r o d u c e d b y
(v)
Appendix 3
Analytical
Methods
C a r b o n and H y d r o g e n
C a r b o n and h y d r o g e n d e t e r m i n a t i o n s w e r e c a r r i e d o u t b y t h e
microanalyst using conventional combustion techniques.
determined
iodate.
also
acid,
The CC^ was m e a s u r e d i n t h e u s u a l
Samples c o n t a i n i n g n i t r o g e n w e r e a n a l y s e d
Oxford,
C a r b o n was
by o x i d a t i o n t o CC^ u s i n g a m i x t u r e o f o l e u m , p h o s p h o r i c
c h r o m i c a c i d and p o t a s s i u m
of
departmental
b y D r s . W e i l e r and
o r i n t h e d e p a r t m e n t , n i t r o g e n was d e t e r m i n e d
way.
Strauss
using the Kjeldahl
method.
Halogens
A n a l y s e s f o r c h l o r i n e and b r o m i n e were c a r r i e d o u t by t h e
microanalyst
by c o n v e n t i o n a l p o t a s s i u m - f u s i o n and t i t r a t i o n
departmental
methods.
Nickel
N i c k e l was d e t e r m i n e d
g r a v i m e t r i c a l l y , by p r e c i p i t a t i o n w i t h d i m e t h y l -
glyoxime from a n e u t r a l s o l u t i o n .
first
The o r g a n i c m a t t e r
i n t h e compound
r e m o v e d b y o x i d a t i o n w i t h b o i l i n g A.R, c o n c e n t r a t e d
nitric
acid.
was
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