Indian Journal of Chemistry
Vol. 33A, October 1994, pp. 948-951
Synthetic and spectroscopic studies of
some tris(s-fluorophenyl)antimony(V)
diacetates
dichloride were prepared by reported methods 11.12.
2, 4-Dichlorophenoxyacetic
acid (BDH) and 2, 4,
5-trichlorophenoxyacetic acid (BDH) were obtained
commercially and recrystallized before use. All the
solvents
were distilled and dried before use. All the
Ashok Ranjan, A K Saxena & P S Venkataramani*
reactions
were carried out under dry and inert
Defence Materials and Stores Research and Development
atmosphere.
The I H, l3C and 19FNMR spectra were
Establishment, DMSRDE P 0, GT Road, Kanpur 208013
recorded
on
Jeol FX90Q NMR Spectrometer using
Received 25 March 1994; revised 26 May 1994;
TMS,
CDCh
and CF 3COOH as internal standards.
accepted 5 July 1994
The IR spectra were recorded as thin film (KBr)
Some new tris(s-fluorophenyl)antirnony diacetates of in the range 4000-400 em -1'on a Pye Unicam SP3-300
the type (s-FC6H4)3Sb(OCOCH3_nRnhs=m= , p-;
spectrophotometer. The UV absorption spectra were
R = CI, F; n = 0-3 and when R = - OC6H5, - OC6H4CI4, recorded in acetonitrile with a Varian CarylOOO
-OC6H3CI2-2, 40r -C6H2C13 - 2,4,5; n= I) have been
spectrophotometer. Antimony was determined by
synthesised by the reaction of tris (s-fluorophenyl)antithe
reported method 13.The molar conductance of the
mony(V) dichloride and carboxylic acid in presence of
compounds
were determined at 25°C with a Khera
triethylamine or the sodium/potassium salt of carboxylic
digital
conductivity
DC 610 instrument.
acid in presence of 15-crown-5/18-crown-6 as phase
The representative synthetic procedures are
transfer catalyst and characterized on the basis of JR,
discussed as follows:
NMR (lH, l3C, 19F)and UV spectral studies. The van't
Hoff factor 'i', molar conductance and spectroscopic
of
tris(m-fiuorophenyl)antimony(V)
studies reveal that the derivatives are monomeric, Synthesis
non-conducting and probably have a trigonal bipyramidal diacetate (I)
Tris(m-fiuorophenyl)antimony(V)
dichloride
geometry.
(0.95 g, 2.0 mmol) and sodium acetate (0.32 g, 4.0
The dual behaviour of the same acetate and
mmol) were stirred in benzene (100 ml) for 5 h in the
thioacetate Jigands as mono and bidentate ligand in presence of a catalytic amount of 15-crown-5 and
organoantimony
(III and V) compounds always
further refluxed for 1.5 h to ensure the completion of
piqued
researchers
to
investigate
various
the reaction. The reaction mixture was filtered' and
determinant for such properties I -9. Our recent
the filtrate on concentration and addition of pet. ether
studies
of tris(pentafluorophenyl)antimony(V)
(40-60°C) afforded a white crystalline solid, which
diacetates have shown that in such cases the ligand
was recrystallised from benzene:pet. ether (40-60°C)
behaved as monodentate moiety due to electron
mixture (20:80), m.p. 206°C, yield 0.92 g. (92%).
donor behaviour of the pentaftuorophenyl rings!",
whereas,
similar studies with methyl- and
Synthesis
of
tris(m-jluorophenyl)antimony( V)
phenyl-antimony
derivatives have shown that
diphenoxyacetate (XI)
acetates behaved both as bidentate and monodentate
Tris(m-fiuorophenyl)antimony(V)
dichloride
ligand in such derivative+". Hence, it was ofinterest to (0.95 g, 2.0 mmol) and phenoxyacetic acid (0.54 g, 4.0
synthesise, hitherto unexplored class of tris(smmol) were stirred together in presence of triethylftuorophenyl)antimony(V)
diacetates of the type
amine in dry benzene (100 ml) for 8 h and further
(~FC6H4hSb(OCOCH3-nC~h
where n=0-3 and
refiuxed for I h to ensure the completion of the
(s~FC6H4hSb(OCOCH20Rh
where
R=
reaction. The triethylammonium
chloride was
-OC6H5-nCln;
n= 1-3, with a view to studying
filtered off as white amorphous powder (m.p. 248°C)
the coordination
behaviour
of ex-halo- and
and the filtrate on concentration and addition of pet.
ex-aryloxyacetate
ligands
with
such
ether (40-M°C) afforded a white crystalline solid
phenylantimony(V)
derivatives having m- and
which was recrystallized from benzene pet.ether
p-ftuoro substitution on benzene ring.
(40-60°C) mixture (20:80); m.p. 63"C, yield 0.76 g.
(72%).
Experimental
Results and discussion
Phenoxy-ja-chlorophenoxy-acetic
acid, tris(mIn the present investigation,
a series of
ftuorophenyl) / (p-fluorophenyl)
antimony (V)
949
NOTES
tris(s-fluorophenyl)antimony(
V) diacetates have
been synthesized by the reaction of tris(sfluorophenyl)antimony(V) dichloride (s = m and p)
with sodium/potassium
salt of acids (acetic-, r:thaloacetic- and o-aryloxyacetic acid) in the presence
of 15-crown-5/18-crown-6
as phase transfer
catalysts or by the reaction of tris(s-fluorophenyl)antimony(V) dichloride with aryloxyacetic acids in
the presence of triethylamine. The yields were noticed
higher in the former case as compared to the latter
one. All the products are white crystalline sharp
melting solids, soluble in usual organic solvents. The
molecular weights and van't Hoff factor 'i'
(0.98-1.05) of the chelates were determined
cryoscopically in nitrobenzene which showed them
to be monomeric in nature. The elemental analysis
(Table 1) was found to be well in agreement with the
proposed structure
The molar conductance of the compounds were
recorded in methanol and found in the range
18-40 ohm -1 em- mol-I, which confirmed the nonconducting nature of these compounds.
The UV absorption spectra of ligands and their
Table I-Analytical
SI.
No.
Mol.
form.
tris(s-fluorophenyl)antimony(V)
derivatives were
recorded in chloroform in the range 200-400 nm. The
- COO groups showed UV absorption in range
'" 259 nm in all the cases. The aryloxyacetates
exhibited two further absorption bands at ,....,
270 nm
and", 292 nm due to aryloxy moities. As there was no
significant change in absorption peaks of derivatives
and li~ands, it appeared that the - C = 0 and
- C - 0 - Ar centres of e-haloacetates
and
o-aryloxyacetates
are not coordinated
with
antimony in all the compounds prepared.
The
IR
spectra
of ce-haloacetate
and
ce-aryloxyacetate
derivatives
of
tris(s-fluorophenyl)antimony(V)
have
been
recorded both in solid and solution using potassium
bromide and chloroform respectively.
The disappearance
of characteristic
v(OH)
absorption band of ligands at '" 3400 cm - 1 and
presence ofv(C=O) bands at 1645 ± 3,1700 ± 10
and 1690 ± 5 em -1 for acetate, o-haloacetatc and
o-aryloxyacetate
derivatives
respectively
and
v(C - 0 - C) deformation band at '" 805 em -1 for
data of tris(s-fluorophenyl)antimony(V)
m.p.
Cc)
a
Found (Calc.), %
b
C22HISf304Sb
206
92
II
C22HI2FQ04Sb
44
90
III
C22H12F3C1604Sb
178
86
IV
C22HI4F3CI4Sb
135
80
V
C22HI6F3Ch04Sb
76
85
VI
C22H JsF 304Sb
175
88
VII
C22H12F904Sb
79
86
VIII
C22HJ2F3Cl604Sb
140
90
IX
C22H 14F3Cl404Sb
96
85
X
C22H16F3C1206Sb
105
80
XI
C34H26F306Sb
63
83
72
XII
C34H22F3CI206Sb
76
83
70
XIII
C34H22F3Cl406Sb
70
86
74
XIV
C34H20F3Cl606Sb
58
84
73
,/"
a = Yields obtained using triethylamine.
b = Yields obtained using sodium/potassium
salt of acids.
diacetates
Yield (%)
50.29
(50.32)
41.72
(41.73)
36.08
(36.10)
39.83
(39.86)
44.45
(44.48)
50.23
(50.32)
41.69
(41.73)
36.08
(36.10)
39.82
(39.86)
44.43
(44.48)
57.52
(57.57)
52.43
(52.47)
49.35
(49.37)
44.53
C
H
3.42
(3.45)
1.89
(1.90)
1.63
(1.65)
2.09
(2.12)
2.69
(2.71)
3.42
(3.45)
1.90
(1.91)
1.62
(1.65)
2.13
(2.12)
2.69
(2.71)
3.66
(3.69)
3.12
(3.10)
2.66
(2.68)
2.23
23.09
(23.18)
19.20
(19.23)
16.62
(16.62)
18.33
(18.36)
20.46
(20.49)
23.16
(23.18)
19.21
(19.23)
16.60
(16.63)
18.32
(18.36)
20.43
(20.49)
17.17
(\ 7.17)
15.63
(15.64)
14.72
( 14.71)
13.30
Sb
(44.58)
(2.20)
(13.31)
950
INDIAN J CHEM, SEe. A, OCTOBER
vsi -
aryloxy derivatives and
CO) band at 1390 ± 12
ern -I for all the compounds indicated the formation
of diacetates'. The comparison of IR spectra of the
compound with respective ligands in solid and
solution did not show any significant shift in
vas(C = 0), vsy(C- 0) and v(C - 0 - C) deformation
bands which in turn showed the lack of coordination
of antimony' through - C = 0 or C - 0 - Ar centre
of the Iigands.
The 1H NMR spectra of the compounds (Xl-X/V)
were recorded in CDCl3 using TMS as internal
reference. The disappearance - OH proton signals
(89.1 ppm) present in Jigands indicated the formation
of acetate derivatives. The singlet for - CH2 protons
in the derivatives at 84.70 ± 0.17 ppm showed that
both the ligands were equivalent and thus seemed to
be in one plane. The phenyl protons of m-FC6H4
derivatives being multiplet in the range (87.50 ± 0.6
ppm) were not amenable for interpretation but
phenyl protons of p-fluorophenyl group (compound
VI-X) clearly showed a doublet of doublet at 08.0 ±
0.1 ppm for o-protons and a triplet for m-protons at
87.18 ± 0.9 ppm. These results further indicated that
all the three phenyl rings were in one plane otherwise
there would have been two sets of protons for every
corresponding 0- and m-protons.
The 13C NMR spectra of some representative
compounds (1, 11, VI, IX and XII) have also been
recorded. A signal for - C = 0 group appeared at a
very low field (8174 ± 6 ppm) as expected due to the
presence of strong electronegative oxygen a tom 14.
Due to m-fluorine, there appeared six signals for the
benzene ring in tris(m-fluorophenyl)antimony(V)
diacetates (compound land II) while four 13Csignals
appeared for tris (p-fluorophenyl) antimony(V)
diacetates (compound VI and IX)'4. The singlet for
-CH3, - CF3 and - CH - (compound 1.11 and IX)
indicates that the ligands were equivalent and thus
may be assumed in one plane. The insignificant
change in chemical shift of - C = 0 and C I of
phenoxy ring in the derivatives compared to that of
corresponding ligands '? further denoted the lack of
coordination from carbonyl or aryloxy sites with
central antimony atom. Therefore the ligands in such
cases appeared
as unidentate.
Among the
aryloxyacetates, the 13C NMR of compound XU
has been only studied, in which the - C = 0 and
- CH2 signals appeared in normal range as in other
o-haloacetates'".
The 13C NMR signals for
m-FC6H4- and 4-CIC6H40- appeared in close
proximities, hence were not conclusive.
The 19F NMR spectra of the compounds (I-X)
were recorded in CDCh using CF 3COOH as
reference at 84.26 MHz. The signals for both m- and
1994
p-tluorine appeared in normal range (0 -107.5
± 3.5
ppm)'>. The appearance of one signal for both m- and
p-fluorine in these derivatives confirmed that the
fluorobenzene rings were equivalent and in one plane
otherwise there would have been two signals in the
ratio of2: 1for each fluorine. Similarly, one signal for
- CF 3 chemical shift in tris(s-fluorophenyl)antimony(V) bis(trifluoroacetates) (compound II and
VII) further gave an indication that both the ligands
were equivalent and thus occupied trans position i.e.
an apical.
Thus on the basis of the spectral data enumerated
above, it may be tentatively concluded that all the
acetates under the present study behaved as
un identate ligands and it can be reasonably
concluded that the tris(s-fluorophenyl)antimony(V)
-diacetates and -diaryloxyaccetates were pentacoordinated and have trigonal bipyramidal structure
with more electronegative acetate groups below
and above the plane and less electronegative
group (m- or p-FC6H4) in one plane i.e. equatorial
position": A tentative diagrammatic representation
of the pentacoordinated
structure of the compounds is as follows (Structure-I),
-
Ar
Ar
(I)
WHERE Ar:
m -
FC6H,-.
P - FC6H,-
L =-OOCR(R=-CH3•
-cHll.
-CHCI2,
-CCI3, - CF3,C6HS-' '-CIC6H,OCH2-,
2,' -CI2C6HpCH2-.
2, '.5 - C~C6H20CH2-)
Acknowledgement
We are thankful to the Director, DMSRDE, for
necessary encouragement and permission to publish
the work.
References
1 Mehrotra R C & Bohra R. Metal carboxylate (Academic
Press. London) 1983 and reference therein.
2 Goel R G. Can J Chem, 47 (1969) 4607.
3 Meinema H A & Noltes J G. J organometal Chern, 36 (1972)
313.
4 Goel R G & Ridley D R, J organometal Chem. 38 (1972) 83.
5 Schmidbaur V H. Mitschke K H & Wiidlein S.Zanorg AlIg
Chern, 386 (1971) 147.
6 Frohn H J & Maurer H. Lfiuorine Chern, 343 (1986) 129.
7 Hall M. Sowerby D B & Falshaw C P, J organometal Chern, 315
(1986) 321.
8 Harris G S. Khan A & Lennon I. Jfiuorine Chern, 37 (1987)
247.
NOTES
9 Wieber M, Fetzer-Kremlung I, Reith H & Burschlca C, Z
Naturforch B Chern Soc. 42B (1987) 815.
10 Saxena A K, Ranjan Ashok & Venkataramani P S, Jfluorine
Chern. 64 (1993) 107.
II Vogel A I, Practical organic chemistry (Longmans, London)
1971.
12 Nevett B A & Perry A, Spectrochim Acta A, 3~ (1975) 101.
.--
(
951
13 Schuek & Wofstadt W. Z Anal Chern, 108 (1937) 400.
14 Levy G C, Lichter R L & Nelson G L, Carbon-I3 nuclear
magnetic resonance spectroscopy, 2nd Edn (John Wiley. New
York) 1980.
15 Boden N, Ensley J W, Feeney J & Sutcliffe L H. Malec Phys, 8
(1964) 133.
16 Muetterties E L & Schunn R A. Quart Rev. 20 (1966) 259.