Molecular complexes of cobalt(II) and Zinc(II) chlorides and bromides with 1-piperidinyl dimethylcarbamodithioate (L): Crystal structures of L and [ZnLBr2]

Article abstract of DOI:10.1134/S0036023611020252

Complexes of MX₂(M = Co, Zn; X = Cl, Br) with 1-piperidinyl dimethylcarbamodithioate (L) of composition [MLX₂] have been synthesized. The compounds have been studied by elemental analysis; X-ray diffraction; thermogravimetry; conductometry; magnetochemistry; and IR, ¹H NMR, and electronic absorption spectroscopy. The ligand molecule is coordinated to the metal atoms in a bidentate chelating mode through the thione sulfur atom and the sulfenamide nitrogen atom to form a five-membered chelate ring. The structures of L and [ZnLBr₂] have been determined by X-ray crystallography.

Full text of DOI:10.1134/S0036023611020252

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2011, Vol. 56, No. 2, pp. 184–189. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © I.I. Seifullina, G.N. Khitrich, A.V. Vologzhanina, 2011, published in Zhurnal Neorganicheskoi Khimii, 2011, Vol. 56, No. 2, pp. 222–227.
COORDINATION
COMPOUNDS
Molecular Complexes of Cobalt(II) and Zinc(II) Chlorides
and Bromides with 1ꢀPiperidinyl Dimethylcarbamodithioate (L):
Crystal Structures of L and [ZnLBr2]
I. I. Seifullinaa, G. N. Khitricha, and A. V. Vologzhaninab
a Mechnikov National University, Dvoryanskaya ul. 2, Odessa, 65026 Ukraine
b Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, ul. Vavilova 28, Moscow, 119991 Russia
Received June 16, 2009
Abstract—Complexes of MX2(M = Co, Zn; X = Cl, Br) with 1ꢀpiperidinyl dimethylcarbamodithioate (L) of
composition [MLX2] have been synthesized. The compounds have been studied by elemental analysis; Xꢀray
1
diffraction; thermogravimetry; conductometry; magnetochemistry; and IR, H NMR, and electronic
absorption spectroscopy. The ligand molecule is coordinated to the metal atoms in a bidentate chelating
mode through the thione sulfur atom and the sulfenamide nitrogen atom to form a fiveꢀmembered chelate
ring. The structures of L and [ZnLBr2] have been determined by Xꢀray crystallography.
DOI: 10.1134/S0036023611020252
Dithiocarbamic acid derivatives, as chelating polyꢀ
Complexes were synthesized by the reaction of satꢀ
dentate ligands, attract ever increasing attention of urated solutions of L in diethyl ether and equimolar
coordination chemists. These derivatives have been amounts of CoCl2 and CoBr2 in acetone or ZnCl2 and
used for synthesis of a large amount of different comꢀ ZnBr2 in diethyl ether. The precipitates formed immeꢀ
plexes, which are widely used in modern technologies diately after mixing the solutions were filtered off, washed
[1]. Unfortunately, this is not the case for thiocarbamꢀ with diethyl ether, and fried in air. Yield, 61–82%.
oylsulfenamides, presumably because of their low staꢀ
bility on storage [2, 3]. We are interested in studying
the possibility of increasing their stability by means of
complexation with transition metal ions. The presence
of active donor sites (S and N) and the labile S–N
bond in thiocarbamoylsulfenamides suggests the posꢀ
sibility to synthesize complexes of different composiꢀ
tion, electronic structure, and geometry, which will
exhibit high thermal stability, curing activity, catalytic
activity, and other valuable properties.
In this work, we determined the structure of 1ꢀpipꢀ
eridinyl dimethylcarbamodithioate (L) by Xꢀray crysꢀ
tallography, synthesized its molecular complexes with
cobalt(II) and zinc(II) chlorides and bromides, and
studied their composition, properties, and structure.
Cobalt and zinc in the complexes were determined
complexometrically [8]; chlorine, bromine, and sulfur
were determined by the Schoeniger method; and
nitrogen was determined by the Dumas method [9].
For C8H16N2S2Cl2Co (2) anal. calcd. (%): N, 8.38;
S, 19.19; Cl, 21.22; Co, 17.63.
Found (%): N, 8.49; S, 19.23; Cl, 21.16; Co, 17.68.
For C8H16N2S2Br2Co (3) anal. calcd. (%): N, 6.62;
S, 15.16; Br, 37.77; Co, 13.93.
Found (%): N, 6.81; S, 15.23; Br, 37.85; Co, 13.87.
For C8H16N2S2Cl2Zn (4) anal. calcd. (%): N, 8.82;
S, 18.83; Cl, 20.82; Zn, 19.19.
Found (%): N, 8.34; S, 18.97; Cl, 20.74; Zn, 19.23.
For C8H16N2S2Br2Zn (5) anal. calcd. (%): N, 6.52;
S, 14.93; Br, 37.20; Zn, 15.22.
Found (%): N, 6.64; S, 15.02; Br, 37.31; Zn, 15.18.
The thermal stability of the compounds was studied
EXPERIMENTAL
The reagents were CoCl2 and CoBr2 obtained by in platinum crucibles in the temperature range 20–
dehydration of CoCl2 · 6H2O and CoBr2 · 6H2O, ZnCl2 · 1000 on a PaulikꢀPaulikꢀErdey Q derivatograph in
1.5H2O, HBr, and KI (all of the pure for analysis air. Samples were heated at a rate of 10 K/min. The
grade), as well as zinc powder, Br2, I2, sodium N,N DTA and DTG sensitivity was 1/5 of the maximum
°
С
ꢀ
dimethyldithiocarbamate, and piperidine (all of the one. Al2O3 was used as a reference. The molar electric
pure grade). Zinc bromide was synthesized by the conductivity of the complexes was calculated from the
reaction of zinc powder with HBr and Br2 [4]. Organic resistances of their 0.001 M solutions in CH3CN meaꢀ
solvents were purified by common methods [5]. sured at 25
Ligand L ( ) was synthesized by oxidative condensaꢀ glass cell with platinum electrodes coated with platiꢀ
tion of sodium N,Nꢀdimethyldithiocarbamate and num black. The electronic absorption spectra of soluꢀ
piperidine in the presence of iodine [6, 7]. tions of the compounds in CH3CN were recorded on a
°
С on a L.C.R. E7ꢀ8 digital instrument in a
1
184

MOLECULAR COMPLEXES
185
Table 1. Crystallographic data and refinement parameters for the L and [ZnLBr2] structure
s
Compound
1
5
Molecular formula
FW
C8H16N2S2
204.36
C8H16Br2N2S2Zn
429.54
Symmetry system
Space group
Monoclinic
Orthorhombic
P
21/m
P212121
T
, K
100(2)
7.6401(13)
6.9050(13)
10.2956(16)
104.435(4)
526.0(2)
2
100(2)
12.8057(10)
12.8209(10)
17.2678(14)
90.00
a
, Å
, Å
b
c
, Å
β
V
Z
, deg
, Å3
2835.0(4)
8
F
(000)
ρcalcd, g/cm3
, mm–1
216
1680
1.277
2.013
μ
0.46
7.64
Crystal shape, color
Crystal size, mm
Colorless prism
Colorless prism
0.28
×
0.18
–
×
0.16
0.46
×
0.26 × 0.18
Correction for absorption
Semiempirical on the basis
of equivalents
Tmin
–
–
0.107
0.256
33669
Tmax
Number of measured reflection
Number of unique reflections
Number of observed reflections
Number of parameters
5264
1650 (
R
int = 0.030)
8222 (Rint = 0.085)
(I
> 2σ(I
))
1429
67
6735
275
R1
(
on F for reflections with
I
> 2σ(I
))
0.034
0.093
1.00
0.036
0.074
1.00
wR2
(
on F2 for all reflections
)
GOOF
2
w−1 = σ2 F 2 + aP + bP,
P = 1 3 F + 2F
( )
o c
2
2
Weight scheme
where
(
)
o
(
)
A
B
0.050
0.23
0.022
0.00
Residual electron density (max/min), e/Å3
0.43/–0.39
1.48/–0.73
0.038 (8)
Flack parameter
Specord UV VIS spectrophotometer in quarts cells tone were recorded on a Bruker MSL 400 spectromeꢀ
ter. TMS was used as the internal reference.
with a pathlength of 1 cm. The diffuse reflectance
spectra of the cobalt(II) complexes in the range 4000–
25000 cm–1 were recorded on a PerkinꢀElmer Lambda
9 UVꢀVISꢀNIR spectrophotometer. Magnetic suscepꢀ
tibility was measured by the Gouy method. Calibraꢀ
tion was against Co[Hg(CNS)4]. Diamagnetic correcꢀ
tions were introduced on the basis of increments taken
from [10]. The IR absorption spectra were recorded as
KBr pellets on a Specord 75 IR spectrophotometer in
Xꢀray crystallography. Colorless single crystals of L
and [ZnLBr2] were obtained by recrystallization from
acetone in diethyl ether vapor. An experimental reflecꢀ
tion set was collected at 100 K on a Bruker Apex II
CCD area detector diffractometer with a graphite
monochromator (
λ
Мо
К
,
ω
scan,
2θmax = 60 ). The
°
α
structures were solved by direct methods. All nonꢀ
hydrogen atoms were located from difference electron
Fh2kl
density maps and refined on
approximation. The hydrogen atoms were introduced
in the anisotropic
1
the range 400–4000 cm–1. THe H NMR spectra of
solutions of cobalt(II) and zinc(II) compounds in aceꢀ into geometrically calculated positions and refined as
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 2 2011

186
SEIFULLINA et al.
Table 2. Results of thermal analysis of the complex comꢀ
riding on their bonded carbon atoms with
1.5 eq(C) for the methyl groups and 1.2 eq(C) for the
other H atoms, where (C) is the equivalent temperaꢀ
Uiso(H) =
pounds
U
U
U
Temperature
range accordꢀ
ing to TG, °C
Total weight
loss accordꢀ
ing to TG, %
Comꢀ
pound
T
max according
ture factor of the carbon atom bound to the correꢀ
sponding H atom. All calculations were performed
with the SHELXTL PLUS 5 program package [11].
The crystallographic data and refinement parameters
for the L and [ZnLBr2] structures are summarized in
Table 1. The atomic coordinates and temperature
parameters have been deposited with the Cambridge
Crystallographic Data Centre (CCDC 732405 and
732406) and can be received free of charge through
www.ccdc.cam.uk/conts/retrieving.html (or from
CCDC, 12 Union Road, Cambridge CB2 1EZ; fax:
+44 1223 335 033; or deposit@ccdc.cam.ac.uk).
to DTA, C
°
50–100
0
77( )
1
120–410
87
200( ), 210( )
50–210
260–290
320–380
390–890
0
29
51
79
155( )
280( )
2
340( )
490( ), 570( ), 850( )
RESULTS AND DISCUSSION
50–180
220–280
340–400
430–820
0
21
38
88
155( )
According to elemental analysis data, the products
have the equimolar composition (MX2 : L = 1 : 1, M =
Co, Zn; X = Cl, Br). They are readily soluble in aceꢀ
tone, acetonitrile, ethanol, DMF, and DMSO; modꢀ
erately soluble in chloroform and benzene; and nearly
insoluble in water.
265(
)
3
390( )
460( ), 570( ), 750( )
Thermogravimetric analysis revealed significant
differences in the thermal behavior of L and the comꢀ
plexes. In particular, the DTA curve of 1ꢀpiperidinyl
50–270
290–450
500–820
17
48
85
190( )
dimethylcarbamodithioate at 77 С shows an endotꢀ
°
4
5
300( ), 400( )
620( ), 750( )
herm without weight loss (Table 2), corresponding to
melting. The subsequent thermal events are accompaꢀ
nied by strong weight loss and point to the almost
complete decomposition of L.
In contrast to L, the thermolysis of the complexes
(Table 2) is a stepwise process.
50–280
300–450
480–780
17
63
93
150( )
310( ), 420( )
590( ), 710( )
A specific feature of thermolysis of cobalt(II) comꢀ
pounds is the presence of wellꢀpronounced exotherms
Table 3. Parameters of electronic absorption spectra, molar electric conductivity in CH3CN, and effective magnetic moments
of the compounds at room temperature
Compound
λmax, nm
logε
Transition
λ
,
Ω
–1 cm2 mol–1
–
μeff, μB
345
279
235
1.87
3.95
3.96
n
n
π
π
*
–
1
σ
*
π
*
690, 637, 595
2.36–2.65
3.92
4A2
4T1
(P)
2
3
277
234
n
π
σ*
108
90
4.66
3.99
π
*
676, 621, 606
2.81–3.02
4.02
4A2
4T1
(P)
278
234
n
π
σ*
4.54
–
4.12
π*
278
239
3.81
3.81
n
π
σ
*
*
4
5
96
99
π
279
239
3.81
3.79
n
π
σ
*
*
–
π
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 2 2011

MOLECULAR COMPLEXES
(б)
187
(а)
C(1)
C(2)
C(2)
C(1)
N(1)
N(1)
C(3)
S(2)
S(1)
C(3)
S(2)
S(1)
N(2)
N(2)
C(7)
C(5)
C(8)
C(4A)
C(4)
Zn(1)
C(5A)
Br(1)
C(5)
C(6)
C(4)
C(6)
Br(2)
View of (a) L and (b) [ZnLBr ] (one of the two independent molecules is shown). Thermal ellipsoids are drawn at the 50% probꢀ
2
ability level.
4А2
4Т1
(F)
transitions in the range 6100–7100 and
at 155 С in the DTA curves, which are not accompaꢀ
°
nied by weight loss events on the corresponding TG
curves. At the same time, for the zinc(II) complexes,
no similar effects were observed.
The synthesized complexes have been characterꢀ
ized by physicochemical methods (Table 3). All the
complexes are nonꢀelectrolytes [12].
Comparison of the electronic absorption spectra of
L and those of the complexes shows that the latter lack
a weak band arising from the transition of one of the
electrons of the lone pair at the thione sulfur atom to
5900–7100 cm–1, respectively, which is evidence of
their tetrahedral structure [13]. The complexes are
paramagnetic and highꢀspin ones (Table 3). The
higher μeff values than the spinꢀonly value (3.87 μB) are
caused by the orbital contribution, which is a function
of the ligand field and complex symmetry. The temꢀ
Table 4. Selected vibrational frequencies (cm–1) in the IR
spectra of the compounds
the excited state in the antibonding
π
orbital. This is
evidence that L is coordinated to M through the
thione sulfur atom.
The electronic absorption spectra of the complexes
show an insignificant hypsochromic effect for the
strong absorption bands inherent in dithiocarbamic
Thioamide bands
Comꢀ
pound
I
II
III
IV
V
1
2
3
4
5
1510
1525
1540
1535
1530
1245 1140, 1160 985
1245 1140, 1160 970
1245 1145, 1160 970
1245 1140, 1160 970
1245 1145, 1160 970
560
560
560
560
560
acid derivatives [1] and related to transitions
n
σ
*
in the N–C=S group and * transitions of elecꢀ
π
π
trons from the bonding orbital of the ground state to
the higher energy orbital in the S–C=S group.
The diffuse reflectance spectra of [CoLCl2] and
[
CoLBr2] show the 4А2
4Т1
(
P
)
transitions in the
range 13800–16800 and 13800–17200 cm–1 and the
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 2 2011

188
SEIFULLINA et al.
Table 5. 1H NMR spectra
Compound
δ
, ppm
1
3
4
5
1.6 (m, 6H, CH2ꢀPip), 3.15 (s, 3H, CH3), 3.23 (br s, 3H, CH3), 3.9 (br s), 4.1 (br s, 4H, CH2ꢀPip)
1.2 (br s, 6H, CH2ꢀPip), 32.7 (s, 3H, CH3), 37.7 (br s, 3H, CH3), –19.2 (s), –21.0 (s, 4H, CH2ꢀPip
1.74 (br s, 6H, CH2ꢀPip), 3.2 (br s, 3H, CH3), 3.34 (s, 3H, CH3), 3.7 (br s), 3.9 (br s, 4H, CH2ꢀPip)
1.8 (br s, 6H, CH2ꢀPip), 3.32 (br s, 3H, CH3), 3.5 (s, 3H, CH3), 3.75 (br s), 3.82 (br s, 4H, CH2ꢀPip)
perature dependence of molar magnetic susceptibility
This representation and the concept of thioamide
in the range 100–300 K for [CoLBr2] obeys the Curie– bands [14–16] were used for comparative analysis of
the IR spectra of L and the complexes (Table 4).
2.807
Weiss law χМ
=
which is evidence of the
,
In the spectra, the thioamide I band id significantly
shifted toward higher frequencies and band IV is
slightly shifted toward lower frequencies, whereas the
positions of bands II, III, and V remain unaltered.
This is indicative of the increase in the C–N bond
multiplicity, the dominance of polar structure A, and
the involvement of the thione sulfur atom in coordinaꢀ
tion. It was difficult to conclude on the basis of IR data
whether the sulfenamide nitrogen atom was bound to
T + 23.2
mononuclear character of this complex.
The L molecule contains the dithiocarbamate fragꢀ
ment. Its structure can be represented by three canonꢀ
ical structures with different C–N bond length and
multiplicity:
–S
–S
R
S
R
–S
R
C N+
C N
C N
R'
1
M in the complexes; therefore, H NMR was used
R' –S
S
R'
(Table 5).
A
B
C
1
The H NMR spectrum of L demonstrates the
presence of nonequivalent protons of the methyl
groups at the thiocarbamoyl nitrogen atom, which is
caused by hindered rotation around the C(S)–N
bond. Due to its deshielding effect, one of the methyl
groups gives rise to a broadened singlet at lower field
than the other one. This is evidence of the dominance
of polar structure A. It is likely that the differences in
the chemical shifts of the proton signals of the methylꢀ
ene groups directly bound to the nitrogen atom of the
piperidine ring are caused by their asymmetric posiꢀ
tion with respect to the magnetic anisotropy cone of
the C=S bond.
In the 1H NMR spectra of the complexes, the sigꢀ
nals of the protons of the methyl groups at the thiocarꢀ
bamoyl nitrogen atom are shifted downfield, their
nonequivalence persisting as in the case of L. At the
same time, the proton signals of the methylene groups
at the sulfenamide nitrogen atom are shifted up field,
which is likely due to its involvement in coordination.
Table 6. Selected bond lengths and bond angles in the L and
[ZnLBr2] structures
d
, Å
Bond, Å
Zn(1)–Br
1
5
2.327(1)–2.362(1)
2.334(1)–2.327(1)
2.124(4)–2.139(4)
1.698(5)–1.700(5)
1.767(5)
Zn(1)–S(1)
Zn(1)–N(2)
C3–S(1)
C3–S(2)
C3–N(1)
1.667(2)
1.799(2)
1.334(2)
1.307(5)–1.315(5)
N(1)–C(sp3)*
S(2)–N(2)
1.463(3)–1.467(3) 1.450(6)–1.481(6)
1.655(2)
1.472(2)
1.741(4)–1.743(4)
1.502(6)–1.520(6)
N(2)–C(sp3
)
ω
,
deg
Angle
1
5
Combined IR and 1H NMR data allow us to conꢀ
clude that L acts as a bidentate ligand in the comꢀ
plexes. At the same time, as is known, ligands containꢀ
ing the thioamide group often function as monodenꢀ
tate Nꢀ or Sꢀligands. Therefore, the structure of the
complexes was determined by means of Xꢀray crystalꢀ
lographic study of L and [ZnLBr2] (figure, Table 6).
Br(1)Zn(1)Br(2)
N(2)Zn(1)Br(2)
S(1)Zn(1)Br(1)
S(1)ZnN(2)
113.99(3)–114.42(3)
110.9(1)–112.3(1)
116.70(4)–115.60(4)
88.6(1)–90.5(1)
C(sp3)N(1)C(sp3
S(1)C(3)N(1)
S(1)C(3)S(2)
S(2)C(3)N(1)
C(3)S(2)N(2)
)
114.7(2)
124.6(1)
121.2(1)
114.2(1)
108.3(1)
116.8(4)–117.5(4)
121.6(4)–122.4(3)
124.2(3)–124.7(3)
112.9(3)–114.2(4)
102.6(2)–103.9(2)
According to the data obtained, the lengths of sinꢀ
gle C–N and C–C bonds and bond angles in the N,N
ꢀ
dimethyl and piperidine moieties have common values
[17]. The heterocyclic ring has a chair conformation in
3
all cases, although, in both independent [ZnLBr2
]
* The symbol C(sp ) denotes the methyl carbon atoms bound to the
N(1) atom and the carbon atoms of the piperidine ring bound to
the N(2) atom.
molecules, this moiety is inverted with respect to the
N(2) atom as compared with the initial ligand in such
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 2 2011

MOLECULAR COMPLEXES
189
a manner that the chelating (S,N) coordination of L
ACKNOWLEDGMENTS
becomes possible (figure). This fact indicates that the
S–N bond is single, which is supported by its length
(Table 6) and the pyramidal geometry of substituents
at the N(2) atom (figure).
This work was supported by the Council for Grants
of the President of the Russian Federation (grant
nos. MKꢀ966.2008.3 and NShꢀ3019.2008.3).
The L molecule is coordinated to the zinc atom as
a bidentate chelating ligand to form a fiveꢀmembered
chelate ring. In addition to the sulfur and nitrogen
atoms of L, the zinc coordination sphere contains two
monodentate terminal bromide ions. The coordinaꢀ
tion polyhedron of zinc is a distorted tetrahedron,
which is caused by different natures of the coordinated
atoms. The presence of three types of surrounding
atoms (Br, S, N) is responsible for both different
lengths of coordination bonds and a wide range of
bond angles at the zinc atom. The largest bond angles
are SZnN and BrZnBr corresponding to maximum
repulsion of the lone pairs of bulky bromine and sulfur
atoms, and the SZnN bond angles are the smallest
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11. G. M. Sheldrick, SHELXTL, Ver. 5.10, Structure
Determination Software Suite, Bruker AXS, Madison,
WI, USA, 1998.
The N,Nꢀdimethyldithiocarbamate moiety of L is
roughly planar in both the free state (the deviation of
the atoms form the C(1)–C(2)–N(1)–C(3)–S(1)–
S(2) plane is 0.0(1) Å) and coordinated state (the deviꢀ
ation of the atoms is 0.1(1) Å). The N(1)–C(3) and
C(3)–S(1) bond lengths (
≈
1.3 and 1.7 Å, respecꢀ
≈
tively) are evidence of their multiple character. Hence,
the geometry of the N,Nꢀdimethyldithiocarbamate
moiety is consistent with IR spectroscopy evidence
about the dominance of polar resonance structure A
for the free ligand. Moreover, the coordination of L to
zinc leads to a pronounced elongation of the C=S and
N–S bonds (by 0.03–0.09 Å) and shortening of the
C–N and C–S bonds (by 0.03 Å), which indicates that
structure A persists in the coordinated ligand.
12. W. J. Geary, Coord. Chem. Rev. 7 (1), 81 (1971).
13. A. B. P. Lever, Inorganic Electronic Spectroscopy
(Elsevier, Amsterdam, 1984; Mir, Moscow, 1987).
14. C. N. R. Rao and R. Venkataraghavan, Spectrochim.
Acta 18 (3), 541 (1962).
Thus, Xꢀray crystallography, IR spectroscopy, and
1H NMR provide consistent data for L and [ZnLBr2].
Hence, we can conclude that the cobalt(II) and
zinc(II) complexes are isostructural, with the same
bidentate chelating coordination of 1ꢀpiperidinyl
dimethylcarbamodithioate through the thione sulfur
atom and the sulfenamide nitrogen atom.
15. K. A. Jensen and P. H. Nielssen, Acta Chem. Scand. 20
(3), 597 (1966).
16. C. Daescu, R. Bacaloglu, and G. Ostrogovich, Bul. Sti.
Tehn. Inst. Politehn. Timisoara. Ser. Chim. 18 (2), 121
(1973).
17. F. H. Allen, O. Kennard, D. G. Watson, et al., J. Chem.
Soc., Perkin Trans. 2, S1 (1987).
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