Pergamon
SO277-5387(96)00258
The coordination chemistry of (2=thiazolin2-yl)hydrazine hydrochloride (TzHyHCl)-II.
Study of its interaction with zinc(I1) and
cadmium(I1)
A. Bernalte-Garcia,“*
M. A. Diaz-Diez,” F. J. Garcia-Barros,”
F. J. Higes-Rolando,”
A. M. Pizarro-Gal&n,” J. D. Martin-Ramosh
C. Valenzuela-Calahorro’
.‘Departamento
de Quimica
hDepartamento
de Mineralogia
‘Departamento
de Quimica
Inorginica,
Facultad de Ciencias,
Badajoz. Spain
Universidad
y Petrologia, Facultad de Ciencias.
Granada. Spain
Inorginica,
(Received
Facultad
de Farmacia,
Spain
I April 1996 ; accepted
de Extremadura.
Universidad
[Jniversidad
de Granada.
de Granada.
and
0607 I
18Oil
I807 I Granada,
17 May 1996)
Abstract-The
complexation
equilibria of (2-thiazolin-2-yl)hydrazine
hydrochloride
(TzHyHCl) with zinc( II)
and cadmium(I1) have been studied in aqueous solution at 298 K and 0.1 M ionic strength in NaCIO,. The
formation constants were determined
and are discussed in terms of the characteristics
of the ligand. The
nHzO have been isolated and their crystal structures
compounds
[ZnCl(TzHy),]Cl
and [Cd(TzHy)(p-Cl),];
determined.
In the Zn” compound,
the geometry around the central atom is a distorted trigonal-bipyramid
composed of four nitrogen atoms from two TzHy ligands and one chlorine. The Cd” complex is polymeric.
with octahedrally
coordinated
cadmium linked into infinite chains by double (p-chloro) bridges. The coordination sphere around each cadmium center is completed by two nitrogen atoms from a TzHy ligand. In both
cases, the crystal structure is stabilized by an extensive hydrogen-bond
network. Copyright
(‘ 1996 Elsevier
Science Ltd
Ke~~~rl.s: zinc(I1) complex : cadmium(I1)
complex ; thiazoline
In a previous paper [l], we have described the crystal
structure of (2-thiazolin-2-yl)hydrazine
hydrochloride
(TzHyHCI) together with its coordination
behaviour
and equilibria study with nickel(I1) in aqueous solution as well as the isolation and crystal structure
of the compound
diaquabis[(2-thiazolin-2-yl)hydrazine]nickell(II)
chloride dihydrate.
In this paper we
report our investigations
of the coordination
behaviour of TzHyHCI with Zn” and Cd” in aqueous solution. Likewise, the solid phase obtained
by the
reaction between the ligand and the aforementioned
* Author
to whom correspondence
: hydrazine.
divalent cations have been characterized
analysis. and X-ray diffraction.
by elemental
EXPERIMENTAL
Reqegrr1t.s
The
ligand
(2-thiazolin-2-yl)hydrazine
hydrochloride (TzHyHCI)
was prepared
according
to a
reported procedure [2], taking into account published
modifications
[3] and recrystallized from ethanol.
Zinc( II), and cadmium(l I) stock solutions were prepared and standardized as usual [4]. The ionic strength
of the solutions was adjusted to a perchlorate
con-
should be addressed.
297
298
A. Bernalte-Garcia
centration of 0.1 M by addition of sodium perchlorate.
Sodium hydroxide stock solutions were prepared by
dilution of a concentrated
solution of sodium hydroxide, according to Kolthoff et al. [.5]. These solutions
were kept under CO,-free
atmosphere
and standardized by titration
against potassium
hydrogen
phthalate.
All other chemicals were AR grade and
used without further purification.
Preparation
of the complexes
The crystals of Zn” and Cd” complexes
were
prepared, in the same manner as analogous
nickel
ones, by evaporation
of relevant water solutions, as
described elsewhere [l]. Found : C, 19.7 ; H, 3.7 ; N,
22.7; S, 17.2 ; Zn, 17.4. Calc. for C,H&l,N,S,Zn
: C,
19.4; H, 3.8; N, 22.7; S, 17.3; Zn, 17.6%. Found: C,
11.5; H, 2.7; N, 13.1; S, 9.0; Cd, 34.2. Calc. for
C,H,Cl?N,OSCd:
C, 11.3; H, 2.8; N, 13.2; S, 10.0;
Cd, 35.3%.
Instrumental
et al.
are given in Table 1. Examination
of three standard
reflections, monitored after 97 scans, showed no sign
of crystal deterioration.
The data were corrected for
Lorentz and polarization
effects, and were also corrected for absorption
effects using an empirical
method based on azimuthal scan data. The structures
were solved by direct methods and subsequent Fourier
differences using the SHELXTL-IRIS
program [8]
and refined by full-matrix least-squares. The H-atoms
were located from a differential Fourier synthesis, and
included in the calculation with estimated isotropic
displacement
parameters
without refinement (riding
model). All calculations were performed with a Silicon
Graphics Iris Indigo XS24.
Thermal parameters
and atom coordinates
have
been deposited with the Cambridge Crystallographic
Data Centre.
RESULTS
AND DISCUSSION
The analytical results agree with the molecular formulae C,H,,Cl,N,S,Zn
and C3H9Cl*N30SCd for the
colourless Zn” and Cd” complexes, respectively.
procedures
Potentiometric
Chemical analyses of carbon, hydrogen, nitrogen
and sulfur were performed
by means of microanalytical methods using a Perkin-Elmer
240C microanalyser. In both complexes, the metal content was
estimated by thermogravimetry
as oxide for the Zn”
and as sulfide in the case of Cd”. IR spectra were
recorded on a Perkin-Elmer
FT-IR 1720 spectrophotometer,
using KBr as dispersing
agent. TG
studies were carried out on a Mettler TA-4000 instrument. The procedures and apparatus used for potentiometric
measurements
were described
in detail
previously [l]. Briefly, measurements
were made at
25 fO.l”C and 0.1 M (NaClO,) ionic strength. The
electrode system was calibrated in terms of hydrogen
ion concentration
by performing
strong acid versus
strong base titrations [6]. Concentration
of ligand in
the experimental
solutions was always 2 x 10-j mol
dmm3, and successive 1 : 1, 2: 1 and 3 : 1 ligand-tometal ratios were investigated. The numerical analysis
of all the experimental
e.m.f. data were carried out
with the computer program SUPERQUAD
[7]. All
calculations
were performed
on an IBM RS/6000
computer (Computer Center, University of Extremadura). X-ray powder diffraction was obtained through
a Philips
PW-1700
diffractometer
using Cu-K,
radiation.
Crystal structure determinations
Crystal data, data collection and refinement details
for [ZnCl(TzHy),]Cl
and [Cd(TzHy)(p-Cl),];nH,O
studies
The final stoichiometries
and formation constants
of the complexes formed were determined by means of
the computer program SUPERQUAD
[7] to identify
that which, according to x2, best fitted the experimental data. The chemical models yielding the best
fits between the measured and calculated titration
curves, together with the refined formation constants,
and statistical parameters (SIGMA and x2), are compiled in Table 2. Metal hydrolysis reactions of the sort
described by Baes and Mesmer [9] were incorporated
into every chemical model tried. It was verified that
all the proposed species (denoted as M,(TzHy),H,)
existed in significant concentrations
over a reasonable
data range.
It can be seen that for the TzHyHCl/Zn”
system
while in the titration curve with a relation ligand:
metal of 1 : 1, the apparently
simple model of 111
satisfied the experimental
data ; in the titration curve
2 : 1 the combination
of complexes 111 and 122 gave
the best agreement.
With respect to the relation
ligand : metal of 3 : 1, the model chosen, formed by
122 and 133, resulted in a satisfactory numerical and
graphical fitting. With respect to the TzHyHCl/Cd”
system, it can also be seen from the aforementioned
Table 2 that all titration curves contain the complex
133. In addition to this species the existing experimental evidence was sufficient to determine with accuracy that the 111 complex is present in the titrations
with relative ligand : metal of 1 : 1 and 2 : 1. The experimental results show that in all M,(TzHy),H,
complexes detected q has the same value as that of r, which
may be taken as evidence that in the TzHyHCl/Zn”
Coordination
Table 1. Crystal
data, data collection
behaviour
and refinement
Crystal shape
Size (mm)
Chemical formula
Formula weight
Crystal system
Space group
0 (A)
h (A)
(’(A)
B()
Cell volume
%
Independent
reflections
Observed reflections
No. of refined parameters
R
R,,
GOF
P”,,. (e A-‘)
Table 2. Formation
details for [ZnCI(TzHy),]Cl
TzHyH+/Cd*+(2/1)
TzHyH+/Cd2+(3/1)
Prismatic
0.50 X 0.45 X 0.35
C,H,Cl,N,OSCd
318.5
Monoclinic
P2,/C
13.244(2)
10.349(l)
7.086(l)
102.84(l)
946.9(4)
4
2.234
30.41
616
Siemens P4
MO-K, (A = 0.71073 A)
20-e
2.G60.0
-18<h<l8;-14<k<l
_ I <I<9
2732
25 16 [F > 2a(F)]
100
0.027
0.036
1:[0~(F)+0.0005
FZ]
constants
Description
only
the
~_~~..
1.09
0.57, -0.55
(log 8) at 25 “C and I = 0.1 mol dm-’
-
and
TzHyHCl/Cd”
systems
(TzHyH)+ acts as ligand.
n&O
Pyramidal
0.40 X 0.22 X 0.20
C6H&lZN6S2Zn
370.6
Orthorhombic
Pna2,
9.242(l)
10.180(l)
14.636(2)
[Zn(TzHyH)13+
[Zn(TzHyH)13+
[Zn(TzHyH)$+
[Zn(TzHyH),]“+
[Zn(TzHyH)J’+
[Cd(TzHyH)13+
[Cd(TzHyH),]‘+
[Cd(TzHyH)IZ+
[Cd(TzHyH),]‘+
[Cd(TzHyH)#’
TzHyH+/Cd’+(l!‘l)
nH@
__.._
[Cd(TzHy)($l),l,.
Species
TzHyH’/Zn’+(3/1)
and [Cd(TzHy)(&l)J;
[ZnCI(TzHy),]CI
System
TzHyH+/Zt?‘(l/l)
TzHyH+/Zt?‘(2/1)
299
with Zn” and Cd”
1377.0(4)
4
1.788
24.62
752
Siemens P4
MO-K, (I. = 0.71073 E\)
28-0
2.0-55.0
-l<h<12;-l<k<l3
-1<1<18
1747
1623 [F > 2a(Q]
153
0.038
0.048
l/[u’(F) +0.0006 F’]
1.26
0.50, -0.43
(A’)
D, tg cm~ ‘)
b (cm ‘)
F (000)
Diffractometer
Radiation
Collection method
20 range
Index ranges
k.xl
of TzHyHCl
species
of the structures
The structure
of [ZnCl(TzHy),]Cl
consists
of
[ZnCl(TzHy),] + cations and chloride anions. Figure
1 shows the molecular structure of the cation complex
and the atom numbering system used. Selected bond
lengths. angles and the hydrogen contacts are listed in
Table 3. Within the cation, the geometry around the
log B
x2
x
9.80(l)
9.85(l)
20.69(2)
20.65(l)
28.78(2)
10.51(l)
30.32(8)
10.90(3)
31.35(l)
31.84(l)
10.00
9.33
2.9
1.7
8.67
1.4
3.53
3.1
10.57
0.9
11.20
-__
1.6
zinc atom may be described as a distorted trigonalbipyramid, according to the value of 0.84 found for
the index of trigonality Z[T = (j?-- u.)/60, where a and b
are the N(6)-Zn-N(3)
and N(4)-Zn-N(1)
bond
angles, respectively]
[lo]. The coordination
polyhedron comprises one chlorine atom [Cl(l)] and two
thiazolinic nitrogens [N(l), N(4)] in the equatorial
positions,
and two terminal
hydrazinic
nitrogens
[N(3), N(6)] in axial positions. The zinc atom lies
0.034 8, out of the plane of the N(l), N(4) and Cl( 1)
atoms toward the N(3) atom. The whole molecule
300
A. Bernalte-Garcia
et al.
Cl(l)
Fig.
1. Molecular
structure
of the [ZnCl(TzHy),]
Table 3. Selected bond lengths
Zn-Cl(
1)
Zn-N(1)
Zn-N(3)
S(l)-C(3)
S(2)-C(6)
N(4)-C(5)
N(l)-C(I)
N(3)-N(2)
C(2)-c(3)
C(5)-C(6)
Cl(l)-Zn-N(4)
N(4)-Zn-N(1)
N(4)-Zn-N(6)
Cl(l)-Zn-N(3)
N( I)-Zn-N(3)
C(l)-S(l)-C(3)
Zn-N(4)-C(4)
C(4)-N(4)-C(5)
Zn-N(l)-C(1)
Zn-N(6)-N(5)
N(6)-N(5)-C(4)
N(3)-N(2)-C(1)
S(l)-C(l)-N(2)
S(2)-C(4)-N(4)
N(4)-C(4)-N(5)
N(4)-C(5)-C(6)
2.271(2)
2.010(5)
2.231(5)
1.824(g)
1.772(11)
1.457(9)
1.291(8)
1.423(7)
1.523(9)
1.472(15)
117.6(2)
121.3(2)
76.2(2)
97.0(l)
79.1(2)
89.6(3)
116.1(4)
111.6(6)
114.3(4)
106.1(3)
117.5(5)
117.4(5)
118.1(4)
117.7(5)
123.0(6)
110.7(7)
Bond A..
Position
Cl(2).
Cl(2).
Cl(2).
Cl(2).
Cl(l).
Cl(l).
H-D
. .H(l4)-N(6)
.H(6)-N(3)
.H(13)-N(6)
.H(5)-N(2)
.H(7)-N(3)
.H(l2)-N(5)
+ cation, showing the atom-numbering
drawn at a 50% level.
(A), angles (“) and hydrogen
112-x. 1/2+y, 1/2+z
x,y. 1+z
--x, -y, 1/2+z
-1/2+x,
1/2-y,
1 +z
_ 1/2+x, 1/2-y, z
-x, -4’. -1/2+z
ellipsoids
bonds for [ZnCl(TzHy),JCl
S(I)-C(I)
S(2)-C(4)
N(4)-C(4)
N(l)-C(2)
N(6)-N(5)
N(5)-C(4)
N(2)-C(1)
2.046(6)
2.312(6)
1.745(6)
1.736(7)
1.296(8)
1.458(8)
1.407(8)
1.337(S)
1.331(7)
Cl( 1)-Zn-N(
1)
Cl(l)-Zn-N(6)
N(l)-Zn-N(6)
N(4)-Zn-N(3)
N(6)-Zn-N(3)
C(4)-S(2)-C(6)
Zn-N(4)-C(5)
Zn-N(
1)-C(2)
C(Z)-N(l)-C(1)
Zn-N(3)-N(2)
N(l)-C(2)-C(3)
S(l)-C(l)-N(1)
N(l)-C(l)-N(2)
S(2)-C(4)-N(5)
S(l)-C(3)-C(2)
S(2)-C(6)-C(5)
121.0(l)
90.9(l)
99.8(2)
97.1(2)
171.4(2)
89.6(4)
131.8(5)
132.4(4)
112.6(5)
105.3(3)
110.5(5)
118.4(4)
123.5(5)
119.3(5)
106.6(5)
109.0(6)
A.. .D (A)
A.. .H-D
3.249(5)
3.242(6)
3.302(5)
3.234(6)
3.492(5)
3.581(6)
162.9(l)
163.4(l)
129.2(l)
178.0(l)
139.2(l)
159.0(l)
Zn-N(4)
Zn-N(6)
of D
scheme. The thermal
(“)
are
Coordination
behaviour
of TzHyHCl
exhibits pseudo-C1 symmetry with the C, axis passing
through the Zn-Cl(l)
bond.
The Zn-Cl(l)
distance of 2.271(2) A is comparable to the value observed for other five-coordinate
zinc(l1) complexes [I 11. The Zn-N(axia1)
distances
[2.231(5) A and 2.312(6) A] are appreciably
longer
than the Zn-N(equatoria1)
distances [2.010(5) A and
2.046(6) A]. Several molecular orbital treatments
of
trigonal-bipyramidal
coordination
have predicted
Fig. 2. Stereoscopic
view of the hydrogen
with Zn” and Cd”
301
contradictory
results about the relative strength of
axial USequatorial bonds for (n - I)d”’ systems. In this
sense, Herlinger et al. [12] have pointed out that the
crystal packaging effects could play an important role
in the nonequivalency
of the bond lengths. According
to the above, and neglecting the electronic factors due
to the central atom. our data can be explained by
the result of two contributions:
one is the different
hybridation
of the nitrogen atoms in the hydrazine
bond network
of [ZnCI(TzHy)JCI.
302
A. Bernalte-Garcia
et al.
Fig. 3. View of the polymeric chain in [Cd(TzHy)(p-C1)J;nH20, showing the atom-numbering scheme. The thermal
ellipsoids are drawn at a 50% level.
( _.rp3) and in the thiazoline (- sp’) which leads to a
decrease of the covalent radius of nitrogen. The other
is the different behaviour of these atoms in the formation of hydrogen bonds. Thus, N(1) and N(4) do
not participate in hydrogen bonding, whereas N(6)
forms two strong hydrogen bonds and N(3) is
involved in one weak and one strong hydrogen bond.
The two five-membered chelate rings are essentially
with maximum
mean-plane
deviations
planar,
observed for the thiazolinic nitrogens [N(l) 0.046 A,
N(4) 0.076 A] ; the angle between the normals to the
best chelate planes is 53.2”. Bonds lengths and angles
in the organic ligands are similar to those obtained in
TzHyHCl and [Ni(TzHy)2(H,0)2]C12*2H20 [l] and
indicate that the organic moiety preserves the thiazoline-hydrazine form. The puckering parameters
for the S(l)-C( I)-N( I)-C(2)-C(3)
thiazoline
ring (q2= 0.150A and +2 = 135.1”) describe a slightly
distorted form intermediate between envelope and
half-chair conformations [13]. For the other thiazoline
ring, with q2 = 0.117A and & = 139.4”, the value is
close to the value (144”) appropriate to one envelope
conformation with apex at C(6).
As pointed out above, the crystal packaging is determined by a network of hydrogen bonds in which all
hydrazinic nitrogen atoms act as hydrogen donors,
while the chloride anion [C1(2)] and coordinated
chlorine [Cl(l)] act as acceptors. A stereoscopic view
showing this network is given in Fig. 2.
The cadmium compound contains water molecules
of crystallization
and polymeric [CdCl,(TzHy)],
chains in which the units are linked by double (pchloro) bridges. The chains run along the crystallographic c axis. A view of one segment of the polymer
is given in Fig. 3. Selected bond lengths, angles and
the hydrogen contacts are listed in Table 4. The octahedral coordination sphere of Cd” is completed by
two cis nitrogen atoms from the TzHy ligand which
acts as didentate. The octahedron is appreciably distorted with the ligand-metal-ligand
bite angles varying between 104.6(l)’ and 72.2(l)“.
The chlorine bridges are very asymmetric ; while the
Cd-Cl(la)
[2.556(l) A] and Cd-Cl(2a)
[2.605(l)
A] distances are similar to those found in several compounds involving chlorine bonded to two cadmium
atoms [1417], the Cd-Cl(l)
[2.745(l) A] and
Cd-U(2)
[2.719(l) A] distances are significantly
greater and are comparable with the distances found
for chlorine atoms bonded to three cadmium atoms
[ 17-201. In similar form to that observed in the zinc(I1)
complex, and for analogous reasons, the metal-hydrazinic nitrogen bond Cd-N(3)
[2.449(2) A] is longer
than the metal-thiazolinic nitrogen bond Cd-N( 1)
[2.241(2) A].
Likewise in the zinc(I1) complex, the chelate ring is
planar, with maximum mean-plane deviation for the
thiazolinic nitrogen N( 1) [0.042 A]. Complexation to
the metal does not dramatically affect the geometry
Coordination
behaviour
of TzHyHCl
303
with Zn” and Cd”
Table 4. Selected bond lengths (A), angles (“) and hydrogen bonds for [Cd(TzHy)(p-Cl),]. *nH,O
-Cd-N(3)
Cd-Cl(Z)
Cd-CI(
la)
S-C(I)
N(3)--N(2)
C(l)-N(1)
C(2)-N(1)
Cl(Z)-Cd(b)
N(3)-Cd-Cl(l)
Cl(l)-Cd-Cl(2)
Cl(l)-Cd-N(l)
N(3)-CId-Cl(la)
Cl(Z)-Cd-Cl(la)
N(3)-Cd-Cl(2a)
C1(2)-Cd-Cl(2a)
Cl(la)-Cd-Cl(2a)
Cd-N(3)-N(2)
S-C(I)-N(1)
C(3)-C(2)-N(
1)
N(3)-N(2)-C(
1)
Cd-Cl(Z)-Cd(b)
Cd-N(
l)-C(2‘1
2.449(2)
2.719(l)
2.566(l)
1.756(3)
1.421(3)
1.287(3)
1.471(3)
2.605(l)
86.9(l)
170.8(l)
95.6(l)
101.8(l)
84.5(l)
158.4(l)
104.6(l)
97.4(l)
107.0(2)
116.6(2)
107.9(2)
119.6(2)
94.2(l)
129.9(2)
Bond A.. .H-D
Position
0.. .H(5)-N(2)
0.. .H(6)-N(3)
Cl(l).
.H(7)-N(3)
Cl(l).
.H(2W)-0
‘J(2).
.H(IW)--0
_~ ~~ ---
l-x,
l-x,
I-x,
of D
1/2+y, 112-Z
-y, --I
-y, l-z
x, .Y,z
l-x,
-y,
C(l)-N(2)
C(2)-C(3)
Cl( 1)-Cd(a)
2.745(l)
2.241(2)
2.605(l)
1.808(4)
1.330(4)
1.520(5)
2.556( 1)
N(3)-Cd-Cl(2)
N(3)-Cd-N(l)
Cl(Z)-Cd-N(l)
Cl(l)-Cd-Cl(la)
N(l)-Cd-Cl(la)
Cl(l)-Cd-Cl(2a)
N(l)-Cd-CI(2a)
C(l)-S-C(3)
S-C(l)-N(2)
N(2)-C(l)-N(1)
S-C(3)-C(2)
Cd-Cl(l)-Cd(a)
Cd-N(I)-C(1)
C(l)-N(l)-C(2)
87.2(l)
72.2(l)
89.3(l)
89.8(l)
171.6(l)
83.2(l)
89.6(l)
89.2(l)
118.7(2)
124.6(3)
105.3(2)
94.5(l)
116.2(2)
112.6(2)
A. .D (A)
A. .H-D
2.890(3)
3.042(3)
3.452(2)
3.275(3)
3.206(2)
173.1(l)
159.7(l)
145.8(O)
127.8(l)
162.1(l)
Cd-Cl(I)
Cd-N(
1)
Cd-CI(2a)
S-C(3)
--i
( )
304
A. Bernalte-Garcia
Fig. 4. Stereoscopic
view of the hydrogen
of the organic ligand, although the thiazoline ring is
here more puckered than in the other compounds
containing the TzHy moiety [l]. The puckering parameters for the thiazoline ring (q2 = 0.293 A and
42 = 137.7”) indicate a conformation
near to envelope
with apex at C(3) [ 131.
Into the chains, the Cd.. Cd separations
3.901(l)
A (x, 0.5-y,
-0.5+2
and x, 0.5-y,
0.5+z) are in
good agreement with values obtained in ammonium
et al.
bond network
of [Cd(TzHy)(p-Cl),],
*nH,O.
cadmium chloride [21] and related complexes. The
shortest Cd. Cd separation intra chains is 6.643(l)
A (l-x,
-y, -z).
Besides normal van der Waals interactions,
the
structure is stabilized by a complicated
hydrogenbond network (Fig. 4) in which each water molecule
participates in four hydrogen bonds, acting as bridge
between three adjacent chains. Moreover,
contact
between neighbouring
chains is reinforced by direct
Coordination
behaviour
hydrogen bonds involving terminal hydrazinic
iw N(3) as donors and CI( I) as acceptors.
of TzHyHCl
nitro-
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