Synthesis and structure of the cobalt(II) coordination compounds with N,N-dimethyl-N',N'-dimethylthiocarbamoylsulfenamide

Article abstract of DOI:10.1134/S1070363211050070

The CoLX₂ complexes were obtained by the reaction of N,N-dimethyl-N',N'-dimethylthio-carbamoylsulfenamide (L) with CoX₂ (X = Cl, Br, I, NCS). The complexes were investigated by elemental and X-ray analysis, IR, ¹H NMR, and

Full text of DOI:10.1134/S1070363211050070

ISSN 1070-3632, Russian Journal of General Chemistry, 2011, Vol. 81, No. 5, pp. 840–844. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © G.N. Khitrich, I.I. Seifullin, N.V. Khitrich, 2011, published in Zhurnal Obshchei Khimii, 2011, Vol. 81, No. 5, pp. 753–757.
Synthesis and Structure of the Cobalt(II) Coordination
Compounds with N,N-Dimethyl-N',N'-
dimethylthiocarbamoylsulfenamide
G. N. Khitrich, I. I. Seifullin, and N. V. Khitrich
Mechnikov Odessa National University, Dvoryanskaya ul. 2, Odessa, 65082 Ukraine
e-mail: galina_khitrich@ukr.net
Received March 4, 2010
Abstract—The CoLX2 complexes were obtained by the reaction of N,N-dimethyl-N',N'- dimethylthio-carba-
moylsulfenamide (L) with CoX2 (X = Cl, Br, I, NCS). The complexes were investigated by elemental and X-
ray analysis, IR, 1H NMR, and electron spectroscopy, conductometry, magnetochemistry, thermogravimetry. It
is found that these compounds are high-spin complexes of pseudotetraedral structure with bidentate
coordination of L through the thione sulfur atom and sulfenamide nitrogen atom.
DOI: 10.1134/S1070363211050070
Interest in thiocarbamoylsulfenamides as poly-
dentate ligand systems is due to the presence of several
donor atoms (N, S) in their molecules, capable of
binding with the central atom in many ways, with the
formation of coordination compounds of various
composition and structure. The choice of cobalt(II) as
a complexing agent is due to its ability to exist in the
compounds with dithiocarbamic acid derivatives in the
degree of oxidation II, III, and IV [1]. The need for a
comprehensive study of thiocarbamoylsulfenamides
and their complexes complexes is connected not only
with scientific, but also with practical purposes. It is
known [2, 3] that thiocarbamoylsulfenamides are
effective accelerators of vulcanization of the com-
pounds based on natural and synthetic rubbers, ho-
wever they did not find industrial applications because
of their low stability. Therefore, it is urgent to study
the effect of complexation with transition metal ions
on the stability of the resulting compounds and the
prospects of their application in industrial processes.
nitrile, DMF, DMSO, acetone, ethanol, and poorly
soluble in chloroform and benzene, almost insoluble in
water. It should be noted that complex III is unstable:
Over time it changes color from green to brown, which
is probably due to its oxidation by atmospheric oxygen
and the formation of free iodine.
X-ray phase analysis of L and the complexes
showed that each compound was characterized by its
own set of interplanar distances (d, Å) and relative
intensities (I/I0). L: 2.16 (16), 2.49 (22), 2.59 (10), 2.76
(35), 2.8 (33), 2.83 (19), 2.98 (13), 3.12 (33), 3.33
(80), 3.73 (71), 4.59 (53), 4.608 (17), 4.82 (11), 5.23
(99), 5.313 (73), 7.4 (100). [CoLCl2] (I): 2.60 (20),
2.84 (26), 2.90 (29), 3.22 (27), 3.39 (22), 3.52 (26),
3.64 (33), 3.70 (21), 3.99 (26), 4.22 (24), 4.56 (31),
4.91 (100), 5.66 (31), 5.97 (39), 7.12 (53), 8.5 (26).
[CoLBr2] (II): 1.832 (13), 1.888 (14), 1.97 (16), 2.085
(10), 2.205 (11), 2.319 (21), 2.442 (15), 2.58 (12), 2.63
(23), 2.75 (13), 2.866 (44), 2.936 (30), 2.985 (34),
3.133 (34), 3.24 (71), 3.43 (33). [CoL(NCS)2] (IV):
1.82 (17), 1.97 (27), 2.03 (21), 2.14 (25), 2.22 (25),
2.36 (21), 2.43 (40), 2.56 (25), 2.75 (30), 2.84 (40),
2.95 (27), 3.01 (27), 3.25 (23), 3.39 (45), 3.58 (21),
3.88 (47).
This situation defined the purpose of this work:
synthesis, establishment of structure, and investigation
of physical and chemical properties of the new coor-
dinaton cobalt(II) compounds with N,N-dimethyl-N',N'-
dimethylthiocarbamoylsulfenamide (L).
These data point to the chemical idividuality and
crystalline nature of the compounds under study.
To establish the centers of coordination bond
localization, we carried out a comparative analysis of
By the reaction of cobalt(II) salts with L complexes
I–IV were obtained with molar ratio metal: ligand = 1: 1
(Table 1). The compounds are well soluble in aceto-
840

SYNTHESIS AND STRUCTURE OF THE COBALT(II) COORDINATION COMPOUNDS
Table 1. Analytical data of the synthesized complexes
841
Found, %
Calculated, %
Comp.
no.
Formula
N
S
Hlg
24.18
41.79
53.29
−
Co
N
S
Hlg
Co
9.66
7.45
5.99
16.64
21.86
16.81
14.01
37.85
20.11
15.43
12.38
17.39
C5H12N2S2Cl2Co
C5H12N2S2Br2Co
C5H12N2S2I2Co
C7H12N4S4Co
9.52
7.31
5.87
16.51
21.80
16.74
13.44
37.79
24.11
41.72
53.21
−
20.04
15.39
12.35
17.36
I
II
III
IV
infrared spectra of L and the complexes (Table 2)
using the concept of thioamide bands [10–12]. As is
known, the structure of the dithiocarbamate ion as a
fragment of the L molecule can be represented by three
equally probable canonical structures differing by the
length and the multiplicity of the C–N bond:
singlets (3.38, 3.14 ppm), due to the restricted rotation
with respect to the magnetic anisotropy cone of the
C=S bond. Because of deshielding influence of the
latter, one methyl group gives a signal at weaker field
than another. The presence of magnetically nonequi-
valent methyl groups confirms the polar nature of C–N
bond and equal probability of structures A, B, and C.
−S
S
−S
R
R
R
1
In the H NMR spectrum of II the methyl groups
C
N+
C
N
C
N
protons at thiocarbamoyl nitrogen atom remain non-
equivalent (46.6, 44.4 ppm). By comparison with them
the signals of methyl groups at the sulfenamide
nitrogen atom are noticeably broader and even more
displaced downfield (70 ppm), which clearly indicates
its involvement in coordination. Thus, we can
conclude that the bidentate ligand is coordinated to
cobalt(II) cations through the sulfur atom and sulfen-
amide nitrogen atom to form five-membered metal-
ocycle. This complex is paramagnetic and its central
atom is in the oxidation state +2.
−S
−S
S
R'
R'
R'
А
B
C
Table 2 shows that the thioamide I band containing
the main contribution of ν(C–N) undergoes the greatest
changes. A significant shift of this band to higher
frequencies indicates an increase in the multiplicity of
the C–N bond and the increasing contribution of polar
resonance structure A, which clearly indicates the
participation of the thione sulfur atom in the
coordination with cobalt(II).
Note that the ambident NCS group can be bonded
with the complex forming agent through the nitrogen
or sulfur atom or through both at once. According to
the criterion [13], the presence in the IR spectra of
complex IV of the absorption bands at 2065, 875 and
475 cm–1 assigned to ν(CN), ν(CS), and δ(NCS),
respectively, indicates the N-binding of NCS. Basing
on the composition of the complexes, as well as con-
sidering as the most probable the coordination number
of cobalt(II) equal to four, one can assume that the
second center of localization of the coordination bond
is the sulfenamide nitrogen atom. To test this hypo-
thesis we used the 1H NMR spectroscopy.
The values of molar conductivity (λ) of the
complexes in acetonitrile (Table 3) are lower than
those of two-ion electrolytes (120–160 Ω–1 cm2 mol–1
[14]), hence they are non-electrolytes. The exception is
complex III whose solution in acetonitrile is of brown
color, while the solutions of other cobalt(II) complexes
Table 2. Main vibrational frequencies (cm–1) in the infrared
spectra of compounds
Tioamide band, ν
Compound
I
II
III
IV
V
L
1500
1535
1535
1535
1540
1250 1155, 1045
1250 1155, 1055
1250 1160, 1055
1250 1155, 1055
1245 1155, 1055
980
980
985
990
975
560
575
575
580
565
1
I
In the H NMR spectrum of L a singlet (3.10 ppm)
is observed corresponding to six protons of two methyl
groups at the sulfenamide nitrogen atom. At the same
time, the protons of methyl groups at the thio-
carbamoyl nitrogen atom give rise to two broad
II
III
IV
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842
KHITRICH et al.
Table 3. Parameters of the EAS, the values of molar conductivity in CH3CN, and effective magnetic moments of compounds
at room temperature
Compound
L
λmax, nm (log ε)
Transition
n→π*
n→σ*
λ, Ω–1 cm2 mol–1
μeff, BM
345 (1.78)
277 (3.98)
231 (4.07)
690 (2.46), 595(2.58)
278 (3.89)
230 (4.07)
700 (2.72), 641 (2.52), 625(2.54)
275 (3.94)
–
–
π→π*
4A2→4T1(P)
n→σ*
92
99
4.41
4.51
I
π→π*
4A2→4T1(P)
n→σ*
II
233 (4.07)
π→π*
360 (4.12)
292 (4.25)
625 (2.26), 570 (2.74)
338 (3.64)
σg→σu*
σg→σu*
4A2→4T1(P)
n→π*
173
70
3.87
4.39
III
IV
278 (3.99)
n→σ*
230 (4.27)
π→π*
are of blue-green color. Apparently, in the case of III
iodide ion is oxidized by atmospheric oxygen to free
iodine, which is capable to form charge transfer
complexes with thiocarbonyl compounds [15]. The
presence of the absorption bands with maxima at ~ 360
and ~ 290 nm in the EAS of acetonitrile solution of III
(Table 3) characteristic of diiodoiodate(I) ion (πg → σu*
and σg → σug* transitions in the [I3]– ion) confirms this
assumption.
vibratonic structure, and distortion of symmetry of the
complexes.
Measurement of molar magnetic susceptibility of
CoLX2 compounds (Table 3) showed that they are
paramagnetic high-spin cobalt(II) complexes (S = 3/2).
Higher values of μeff than the pure spin value (3.87 BM)
are due to orbital contribution, which is a function of
the ligand field and the symmetry of the complexes.
Based on the analysis of the set of experimental
data the complexes CoLX2 structure can be represented
by V:
The electron spectrum of the L contains a band of
low intensity at ~345 nm associated with the transition
in the excited state on antibonding π-orbital of one of
two unshared electrons localized on the thione sulfur
atom. The absence of this band in the UV spectra of
the complexes clearly indicates the participation of the
thione sulfur atom in the coordination. Bands of high
intensity at ~277 and ~231 nm in the spectra of the
compounds are induced by n → σ* transitions in the
N–C=S group and π → π* transitions from the bonding
orbital of the ground state to the orbital with a higher
energy in S–C=S group typical for derivatives of
dithiocarbamic acid, respectively [1].
H3C
CH3
S
N
C
N
Co
X
H3C
CH3
S
X
V
The thermogravimetry (Table 4) revealed that
thermal decomposition of the complexes occurs in
steps. A feature of their thermal decomposition is the
presence of a distinct irreversible exothermic effect at
130–150°C that is not accompanied by changes in the
sample weight. At these temperatures the bright-blue
complexes are converted to the dark-green insoluble
modifications. The explanation of the nature of these
processes requires further research. The occurring
In the diffuse reflectance spectra (DRS) of the
compounds CoLX2 (see the figure) in the near infrared
and visible regions two bands appear, at 5500–7700
and 14200–16900 cm–1, corresponding to 4A2 → 4T1(F)
4
4
and A2 → T1(P) transitions in the tetrahedral co-
balt(II) complexes [16]. The width and multiplicity of
the DRS bands point to the spin–orbital interaction,
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SYNTHESIS AND STRUCTURE OF THE COBALT(II) COORDINATION COMPOUNDS
843
Table 4. The results of thermal analysis of systems
thermal transformations obviously are accompanied by
an energy gain. The final product of thermolysis of the
CoLX2 complexes is Co3O4 that at heating above 900°C
is decomposed to CoO, showing a reversible endo-
thermic effect in the DTA curve, with an insignificant
weight loss in the TG curve.
Total
Temperature range
t
max by DTA,
Compound
weight loss
on TG, %
for TG, °С
°С
75–200
200–280
280–390
390–650
650–870
870–920
50–190
150(↑)
215(↑)
335(↓)
460(↓), 530(↑)
695(↑), 855(↓)
870(↑),920(↓)
130(↑)
−
I
27
37
57
74
76
−
16
32
82
85
−
Thus, we first obtained pseudotetrahedric molecular
cobalt(II) complexes with N,N-dimethyl-N',N'- dimethyl-
thiocarbamoylsulfenamide and characterized them by a
set of physicochemical methods. The bidentate ligand
in these complexes is coordinated through the thione
sulfur atom and sulfenamde nitrogen atom to form
five-membered metallocycle.
II
190–290
290–390
390–690
840–940
100–180
180–310
500–560
760–810
900–920
270(↓)
360(↑)
565(↑), 690(↓)
920(↓)
140(↑)
235(↓)
560(↑)
800(↓)
910(↓)
EXPERIMENTAL
The starting reagents CoCl2, CoBr2, and CoI2 were
obtained by dehydration of CoCl2·6H2O, CoBr2·6H2O,
and CoI2·6H2O along the procedure in [4]. Co(NCS)2
and KI were of analytical grade, I2, sodium N,N-
dimethyldithiocarbamate and dimethylamine were of
pure grade. Organic solvents were purified by standard
methods [5].
IV
25
68
77
79
and Fe-filter. The IR absorption spectra of the samples
with KBr tablets were recorded on a Specord 75 IR
instrument in the frequency range 400–4000 cm–1. The
1H NMR spectra of solutions of compounds in
(CD3)2CO were recorded on a MSL–400 Bruker
spectrometer, internal reference TMS. Molar con-
ductivity of the complexes were calculated from the
values of the resistivity of 0.001 M solution in CH3CN
measured on a digital measuring unit LCR E7-8 in a
glass cell with platinum electrodes coated with
platinum black at 25°C. The electron absorption
spectra (EAS) of the solutions of compounds in
N,N-dimethyl-N',N'-dimethylthiocarbamoylsulfen-
amide was prepared by the reaction of sodium N,N-
dimethyldithiocarbamate with dimethylamine by the
procedure [6]. The resulting white precipitate was
filtered off, washed with water, and dried in air. It was
purified by a double crystallization from ethanol. The
purity of recrystallized L was monitored by TLC on
glass plates with a layer of neutral Al2O3, eluent CCl4–
hexane 1:2. Yield 76.8%, mp 51°C. The compound is
well soluble in the cold in the diethyl ether, dioxane,
acetone, chloroform, benzene, acetonitrile; in me-
thanol, ethanol at heating; in water it is practically
insoluble.
Synthesis of complexes was carried out by mixing
anhydrous cobalt(II) salts in diethyl ether (CoCl2 in
acetone) with saturated solutions of L in diethyl ether
in equimolar amounts at room temperature. The result-
ing blue (green in the case of CoI2) precipitates formed
were washed with a little diethyl ether and dried in air.
Yields 64–83%.
Cobalt in the compounds was determined by com-
plexonometry [7], chlorine, bromine, and sulfur, by the
Schoeniger method, and nitrogen, by the Dumas
method [8].
3
1
ν×10– , cm–
The diffractograms of the compounds were ob-
tained on a Dron-3 diffractometer with CoKα-radiation
Diffuse reflectance spectra of complexes (1) I, (2) II, and
(3) IV.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 5 2011

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KHITRICH et al.
6. Smith, G.E.P., Alliger, G., Carr, E.L., and Young, K.C.,
CH3CN were recorded on a Specord UV VIS spectro-
photometer in quartz cells with the absorbing layer
thickness 1 cm. The Diffuse reflectance spectra (DRS)
were recorded on a Perkin-Elmer Lambda 9 UV VIS
NIR spectrophotometer in the range 4000-25000 cm–1.
The magnetic susceptibility was measured at room
temperature by Gouy method, with calibration on
Co[Hg(CNS)4]. Diamagnetic corrections were
introduced using the increments from [9]. Thermal
stability of the compounds was studied on a Paulik-
Paulik-Erdey derivatograph in platinum crucibles in
the air in the temperature range 20–1000°C, heating at
a rate of 10 deg min–1. The DTA and DTG sensitivity
was 1/5 of the maximum sensitivity. As a reference
was used Al2O3.
J. Org. Chem., 1949, vol. 14, no. 6, pp. 935–945.
7. Schwarzenbach, G. and Flashka, H., Complexometric
Titrations, Moscow: Khimiya, 1970.
8. Klimova, V.A., Osnovnye mikrometody analiza organi-
cheskikh soedinenii (Basic Micromethods of Analysis of
Organic Compounds), 2nd ed., Moscow: Khimiya, 1975.
9. Kalinnikov, V.T. and Rakitin, Yu.V., Vvedenie v
magnetokhimiyu. Metod staticheskoi magnitnoi vospri-
imchivosti v khimii (Introduction to Magnetochemistry.
Method of Static Magnetic Susceptibility), Moscow:
Nauka, 1980.
10. Rao, C.N.R. and Venkataraghavan, R., Spectrochim.
Acta, 1962, vol. 18, no. 3, pp. 541–547.
11. Jensen, K.A. and Nielssen, P.H., Acta Chem. Scand.,
1966, vol. 20, no. 3, pp. 597–629.
REFERENCES
12. Daescu, C., Bacaloglu, R., and Ostrogovich, G., Bul. Sti.
Tehn. Inst. Politehn. Timisoara, Ser. Chim., 1973,
vol. 18, no. 2, pp. 121–129.
13. Nakamoto, K., IR and Roman Spectra of Inorganic and
Coordination Compounds, Moscow: Mir, 1991.
1. Byr’ko, V.M., Ditiocarbamates, Moscow: Nauka, 1984.
2. Blokh, G.A., Organicheskie uskoriteli vulkanizatsii
kauchukov (Organic Accelerators of Resin Vulcaniza-
tion), 2nd ed., Leningrad: Khimiya, 1972.
14. Geary’ W.J., Coord. Chem. Rev., 1971, vol. 7, no. 1,
3. Koval’, I.V., Usp. Khim., 1996, vol. 64, no. 5, pp. 452–
pp. 81–122.
472.
15. Grand’ A.F. and Tamres’, M., Inorg. Chem., 1969,
4. Handbook of Preparative Inorganic Chemistry, Brauer, G.,
vol. 8, no. 11, pp. 2495–2498.
Ed., vol. 5, Moscow: Mir, 1985.
5. Weisberger, A., Proskauer, E., Riddik, J., and Tups, E.,
16. Lever, A.B.P., Inorganic Electronic Spectroscopy,
Organic Solvents, Moscow: Inostrannaya Literarura, 1958.
part 2, Moscow: Mir, 1987.
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