N,S,O-Containing organic ligands based on salicylaldehyde and 2-thiosubstituted ethylamines and their complexes with CoII, Ni II, and CuII

Article abstract of DOI:10.1007/s11172-007-0210-1

The reaction of 2,2'-di(2-hydroxybenzaliminoethyl) disulfide (H ₂L¹) and 2-[(2-thioethyl)iminomethyl]phenol (H ₂L²) with MCl₂?xH₂O (M = Co, Ni, Cu) afforded the [M₂(L¹

Full text of DOI:10.1007/s11172-007-0210-1

Russian Chemical Bulletin, International Edition, Vol. 56, No. 7, pp. 1374—1379, July, 2007
1374
N,S,OꢀContaining organic ligands based on salicylaldehyde
and 2ꢀthiosubstituted ethylamines and their complexes
with CoII, NiII, and CuII
E. K. Beloglazkina,ꢀ A. G. Majouga, A. N. Chernysheva, R. D. Rakhimov, and N. V. Zyk
Department of Chemistry, M. V. Lomonosov Moscow State University,
1 Leninskie Gory, 119992 Moscow, Russian Federation.
Eꢀmail: bel@org.chem.msu.ru
The reaction of 2,2´ꢀdi(2ꢀhydroxybenzaliminoethyl) disulfide (H2L1) and 2ꢀ[(2ꢀthioꢀ
ethyl)iminomethyl]phenol (H2L2) with MCl2•хH2O (M = Co, Ni, Cu) afforded the [M2(L1)Cl2]
and [M(L2)]2 complexes, respectively. Their structures were determined by the data of elecꢀ
tronic and IR spectroscopy and PM3 quantum chemical calculations. The H2L1 ligand and the
complexes were studied by electrochemistry (CV and using a rotating disk electrode). The
primary electronic changes are localized on the ligand fragment upon the electrochemical
oxidation and reduction of the complexes.
Key words: 2,2´ꢀdi(2ꢀhydroxybenzaliminoethyl) disulfide, 2ꢀ[(2ꢀthioethyl)iminoꢀ
methyl]phenol, nickel(II), cobalt(II), copper(II), transition metal complexes, electrochemistry.
Scheme 1
Transition metal complexes, particularly, of nickel(II),
cobalt(II), and copper(II), with organic N,S,Oꢀcontainꢀ
ing ligands attract attention as models for metal enzymes
and electroactive catalysts.1—3 A series of enzymes of variꢀ
ous structural types containing in the active center one or
two transition metal atoms are presently known.4,5 Most
of them react according to the electron transfer mechaꢀ
nism (redox enzymes). In these redox enzymes, the metal
center usually has a squareꢀplanar or tetrahedral ligand
environment and is coordinated to the N, S, and O atoms
of the protein fragment of the molecule.
The purpose of this work is to synthesize complexes of
nickel(II), cobalt(II), and copper(II) with organic ligands
1 and 2 of the NSO type derived from salicylaldehyde and
2ꢀthiosubstituted alkylamines, which are potentially caꢀ
pable of forming binuclear metal complexes.
was proved by the NMR experiment using NOE. The
irradiation of the proton of HC=N (δ 8.40) results in the
NOE on the protons of the CH2N group at δ 3.94.
Ligand 2 formed from salicylaldehyde and cystamine
(2ꢀaminoethanethiol) via similar reaction (Scheme 2) canꢀ
not be isolated in the pure state: according to the NMR
spectroscopy data, a mixture of the target product, viz.,
benzothiazoline formed due to the interaction of the alꢀ
dehyde group of salicylaldehyde and the amino and
mercapto group of the starting amine,6 and, probably, the
product of oxidation of the target mercaptoimine 2 to the
corresponding disulfide. However, according to the data of
TLC and NMR spectroscopy, ligand 2 is stable in solution.
Results and Discussion
Ligand 1 was synthesized from salicylaldehyde and
cystamine (2,2´ꢀdiaminodiethyl disulfide) hydrochloride
(Scheme 1).
Compound 1 is formed as the single geometric isoꢀ
mer, in which the antiꢀconfiguration of the C=N bond
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1325—1330, July, 2007.
1066ꢀ5285/07/5607ꢀ1374 © 2007 Springer Science+Business Media, Inc.

Complexes of thioimines
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 7, July, 2007
1375
Table 1. UV—Vis spectra of compounds 1, 3, and 5—8
Therefore, further, when synthesizing the complexes of
ligand 2, the latter were not isolated from its ethanolic
solution and the formation of the product was monitored
by TLC (by the disappearance of the starting compounds).
(10–3 mol L–1, DMF)
Comꢀ
pound
λ/nm
Coordination mode
of metal ion
(ε/L mol–1 cm–1
)
1
3
318 (6947), 375 (108)
283 (29508), 321 (14207),
377 (20546), 527 (1464)
271 (122358), 301 (50056),
370 (48943), 675 (845)
290 (38760), 318 (19574),
370 (14729), 527 (2345)
360 (24419), 647 (1938)
318 (5614), 370 (4840),
555 (1016)
—
Scheme 2
Flattened
tetrahedron
Tetrahedron
5
6
Flattened
tetrahedron
Tetrahedron
Tetrahedron
7
8
electronic spectroscopy data: no pronounced absorption
bands are observed in the visible region of the spectrum.
However, the absorption intensity decreases gradually in
the region from 260 to 830 nm, i.e., the visible region
contain several absorption bands and the observed curve
is their envelope.
We failed to prepare crystals of complexes 3—5 suitꢀ
able for Xꢀray experiment. Two structures that satisfy the
elemental analysis and spectral data can be proposed for
the chloroꢀcontaining complexes: binuclear complex A,
in which two disulfide sulfur atoms are involved in coorꢀ
dination of two different metal ions, or structure B with
the bridging chloride anions in which the sulfur atom is
not involved in coordination. 2,2´ꢀDipyridyl disulfide is
described as a bidentate ligand coordinating the metal
atoms only through the nitrogen atoms.
The reactions of ligand 1 with nickel(II), cobalt(II),
and copper(II) chlorides (Scheme 3) afforded complexes
corresponding, according to the elemental analysis data,
to the simplest molecular formula M2(L1)Cl2 (M = Ni,
Co, Cu).
Scheme 3
M = Ni (3), Co (4), Cu (5)
The complexes were characterized by UV—Vis and IR
spectroscopy. According to the IR spectroscopy data,
the formation of the nickel and copper complexes is acꢀ
companied by the lowꢀfrequency shift of vibrations of the
С=N group by 10—15 cm–1 compared to the starting
ligand, indicating that the nitrogen atom of the imino
group is involved in coordination.
The results of studying compounds 1, 3, and 5 by
UV—Vis spectroscopy are presented in Table 1. Only
UV absorption bands corresponding to the π—π* and
n—π* transitions in an organic molecule are observed
for ligand 1. Additional bands of the resolved meꢀ
diumꢀintensity d—d transitions in the visible region
(500—830 nm) are observed for the complexes. Based on
the obtained results on absorption in the visible region
and literature data on the position and intensity of bands
of the d—d transitions for the tetrahedral, planarꢀsquare,
and octahedral nickel(II) and copper(II) complexes,7 we
can assert that the reactions with the copper and nickel
salts gave the complexes containing metal ions in the
tetrahedral and flattened tetrahedral ligand environments.
In the case of cobalt complex 4, no unambiguous conꢀ
clusion about the geometry of the coordination environꢀ
ment of the metal ion can be made on the basis of the
We optimized the geometric parameters of the nickel,
cobalt, and copper complexes of types A and B by the
PM3 semiempirical method8 in the HyperChem program
package (HyperCube Inc., FL, USA). The convergence
gradient is <10 cal Å–1 mol–1. The geometric parameters
of the cobalt and copper complexes were optimized for
the triplet and singlet states of the binuclear complex.
According to the calculation results, complexes 4 and 5

1376
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 7, July, 2007
Beloglazkina et al.
Scheme 4
a
M = Ni (6), Co (7), Cu (8)
b
М = Ni, Co, Cu
The results of IR spectral studies of complexes 6—8
indicate the presence of the С=N group. The electronic
spectroscopy data for compounds 6—8 are presented in
Table 1.
c
Complexes 6—8 contain the ligands with the sulfur
atoms, which is confirmed by the experiment on alkylaꢀ
tion of complex 6: no new compounds were formed upon
the addition of MeI excess to a solution of 6 in DMF.
According to Refs 10 and 11, the test for the bridging
sulfur atom is the ability to alkylate the complex at the
sulfur atom: the complexes with the nonbridging thiolate
ligands form complexes of the corresponding sulfides upon
the addition of alkyl halides, whereas the complexes conꢀ
taining the ligands with the bridging thiolate atoms do not
enter into these reactions.
Fig. 1. Optimized structures of complexes 5 (a), 6 (b), and 7 (c)
(PM3, convergence gradient <10 cal Å–1 mol–1).
should exist in singlet form A. The optimized structure of
complex 5 is shown in Fig. 1, a.
For complex 3, according to the calculation data,
the species with the bridging and nonbridging chlorine
atoms should possess approximately equal thermodynamic
stabilities. Nevertheless, the complex is nonbridged in
this case as well. This assumption is confirmed by a reꢀ
sembling behavior of all three complexes 3—5 during elecꢀ
trochemical investigation (see further).
In the case of ligand 2 (H2L2) capable of being
deprotonated to both the oxygen and sulfur atoms, powꢀ
dery precipitates of the complexes are formed immediꢀ
ately in the reactions with nickel chloride and nickel,
cobalt, and copper acetates (Scheme 4). According to the
elemental analysis data, the isolated complexes have
the molecular formula М(L2). However, for tridentate
ligand 2, according to earlier published data,9 the biꢀ
nuclear structure with the bridging sulfur atoms (C) seems
to be most probable.
The PM3 optimization of the geometry of the nickel,
cobalt, and copper complexes of ligand 2 showed that the
singlet species with the tetrahedral environment of the
metal ion is most stable for complexes 7 and 8 (Fig. 1, c).
At the same time, in the case of complex 6, the geometry
of the coordination environment of NiII represents a
strongly flattened tetrahedron (Fig. 1, b), which agrees
with the electronic spectroscopy data (see Table 1).
To reveal applicability of the synthesized complexes
as electroactive catalysts, we studied ligand 1 and comꢀ
plexes 3—8 by the electrochemical methods (CV and roꢀ
tating disk electrode (RDE)) at a platinum electrode in
a DMF solution.
The NiIIꢀcontaining metal centers in natural synthases
and reductases in the catalytic cycle undergo reduction to
NiI and subsequent methylation at nickel to form the
NiIII—Me organometallic compound, which is transꢀ
formed, in the case of synthase, into the acetyl compound
NiIII—COMe. These organic compounds of nickel(III)
are mediators of the Me groups from the sulfur atom of
the MeS—CoM or MeCO group to various substrates. To
The reactions of cobalt and copper chlorides also afꢀ
ford powdery complexes, whose IR spectra are analogous
to the spectrum of nickel complex 6; however, no satisꢀ
factory elemental analysis data were obtained for them.

Complexes of thioimines
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 7, July, 2007
1377
Table 2. Electrochemical redox potentials (V) for compounds 1
and 3—9 (DMF, Bu4NBF4, Ag/AgCl/KCl (sat.), 20 °С)
5 µA
Comꢀ
poꢀ
und
Oxidation
Reduction
ox
red
E1/2
Epox (reverse –E1/2
–Epred (reverse
anodic peaks)
cathodic peaks)
1
1.28
1.41
(–0.26, 0.40)
1.03 (–0.30, 0.30)
0.96 (–0.22, 0.34)
1.30
0.86
0.88, 1.52 (0.82)
3
4
5
—
—
1.21
—
—
0.58
0.84 (0.64)
0.94 (0.55)
0.90 (0.76)
A
1
B
2
(–0.40, 0.29)
1.01
0.91, 1.29
6
7
1.01
0.87,
1.36
0.70
1.31
0.83
0.78,
1.20
0.78
0.80
1.12 (1.05)
0.76
(0.30, 0.61)
0.78 (0.64)
0.83, 1.25
(1.08)
–2
–1
0
1
E/V
Fig. 2. CV curves for compounds 1 (1) and 9 (2) (DMF,
Bu4NBF4, Pt electrode, 10–3 mol L–1, 20 °C, vs. Ag/AgCl/KCl).
8
9
0.74 (0.34)
1.29
(–0.34, 0.40)
5 µA
use a complex as an electroactive catalyst mediating alkyl
groups, it is necessary that the transfer of at least the first
electron during reduction would be reversible.
The electrochemical redox potentials of compounds 1
and 3—8 are given in Table 2.
C
Compounds 1 and 3—5 are oxidized in one irreversꢀ
ible electrochemical step. Two reduction peaks of the
decomposition products of the oxidized compounds are
observed in the reverse cathodic scan (see Table 2, Figs 2
and 3, peaks А and В).
The compounds under study can be oxidized and reꢀ
duced either at the S—S bond or O—Х bond (Х = Н
or M). To answer the question at which fragment the
oxidation occurs, we carried out an additional electroꢀ
chemical study of 4,4´ꢀdi(benzalimino)ethyl disulfide 9
containing no hydroxyl group. Compound 9 is oxidized in
one twoꢀelectron irreversible step, and the reverse caꢀ
thodic scan also exhibits two reduction peaks of the oxiꢀ
dized products, and the peak potentials for compounds 1,
3—5, and 9 are very close (see Table 2). Our data indicate
A
B
–1
0
1
E/V
Fig. 3. CV curves for compound 5 (DMF, Bu4NBF4, Pt elecꢀ
trode, 10–3 mol L–1, 20 °C, vs. Ag/AgCl/KCl).
that these compounds are oxidized via the same mechaꢀ
nism, presumably the mechanism presented in Scheme 5.
The first reduction peak of the oxidation products of
compounds 1, 3—5, and 9 corresponds, most likely, to
the reduction of the radical formed upon the S—S bond
cleavage, whereas the second cathodic peak corresponds
to the reduction of the R+ species.
Scheme 5
P are products
+ = H+, CoCl+, NiCl+
R

1378
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 7, July, 2007
a
Beloglazkina et al.
d
b
c
e
f
Fig. 4. PM3ꢀcalculated HOMO (a—c) and LUMO (d—f ) for ligand 1 (a, b) and nickel complexes 3 (b, e) and 6 (c, f ).
For complex 5, the oxidation, possibly, involves both
the disulfide fragment and coordinated chloride anions
(this can be indicated by the presence of peak C in Fig. 3).
The compounds are reduced in one quasiꢀreversible
oneꢀelectron step forming radical anions that underwent
slow cleavage at the sulfur—sulfur bond. This is indicated
by the observed reduction peaks of the corresponding
S anions (0.46, 0.24, and 0.40 V for the reduction of
compounds 1, 2, and 4, respectively).
Table 2 and Fig. 4), is directed, most likely, to the imine
C=N bond (potential of the first reduction peak lies in the
region characteristic of imines13).
Thus, the results of the electrochemical study of the
complexes ligands 1 and 2 show that their redox processes
are localized on the ligand fragments rather than on the
metal atoms.
Experimental
To confirm the assignment of the electrochemical oxiꢀ
dation and reduction peaks, we calculated the frontier
orbitals of ligand 1 and its complexes 3—5 by the
PM3 method. The data obtained confirm the concluꢀ
sions: the lowest unoccupied MO (LUMO) of all the
studied compounds are localized at the S—S bond,
whereas the highest occupied MO (HOMO) are localized
at the S—S bond (for the ligand) or at the S—S bond and
coordinated chloride anion (for the complexes). Thereꢀ
fore, it is most probable that the primary electronic
changes are localized on the disulfide fragment. The
HOMO and LUMO of ligand 1 and complex 3 are shown
in Fig. 4.
In the case of complexes 6—8, the oxidation is diꢀ
rected, most likely, to the thiolate fragment, because the
potential of the first oxidation peak lies in the region
characteristic of organic disulfides12 (see Table 2). This is
also indicated by the results of quantum chemical calcuꢀ
lations, according to which the HOMO of all the three
complexes are localized mainly on the thiolate fragment
of the ligand (see Fig. 4).
1
Н
NMR spectra were recorded at 25 °С on a
Bruker—Evanceꢀ400 instrument (400 MHz) in CDCl3. IR specꢀ
tra were obtained on a URꢀ20 instrument in Nujol. Electronic
spectra were recorded on a Perkin—Elmer λꢀ25 instrument.
Electrochemical oxidation and reduction potentials were
measured with a PIꢀ50ꢀ1.1 potentiostat coupled with a PRꢀ8
programmer. Cyclic voltammograms and waves at the RDE were
recorded on a twoꢀcoordinate recorder. Tetrabutylammonium
perchlorate Bu4NBF4 (highest purification grade, 99.8%, Fluka)
served as a supporting electrolyte. The electrolyte concentration
was 0.05 mol L–1
.
2,2´ꢀDi(2ꢀhydroxybenzaliminoethyl) disulfide (1). A solution
of potassium hydroxide (0.5 g, 8 mmol) in a minimum amount
of boiling ethanol was added to a solution of cystamine (2 g,
8 mmol) in ethanol (10 mL). The reaction mixture was stirred
under reflux for 0.5 h. After cooling to ~20 °C, a flaky white
precipitate that formed was filtered off. Salicylaldehyde (2.17 g,
1.87 mL, 16 mmol) was added with stirring to the resulting
solution. The reaction mixture was stirred for 5 h and cooled
to –10 °C. Needleꢀlike yellow crystals that formed were filtered
off and washed with a minor amount of ethanol. After drying in
air, compound 1 (1.55 g, 49%) was obtained as light yellow
crystals, m.p. 76—77 °C. Found (%): С, 59.97; H, 5.44; N, 7.72.
The reduction of complexes 6—8, according to the
electrochemical data and results of calculations (see
C
18H20O2N2S2. Calculated (%): С, 60.00; H, 5.56; N, 7.78.

Complexes of thioimines
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 7, July, 2007
1379
1H NMR, δ: 13.02 (s, 2 Н, ОН); 8.40 (s, 2 H, CHN); 7.32 (dt,
2 H, Ar, J = 7.2 Hz); 7.25 (dd, 2 H, Ar, J = 7.6 Hz); 6.96 (d, 2 Н,
Ar, J = 8.2 Hz); 6.88 (dt, 2 Н, Ar, J = 7.4 Hz); 3.94, 3.04 (both t,
4 Н each, СН2, J = 6.65 Hz). IR, ν/cm–1: 1635 (С=N); 1580,
1500, 1470, 1380, 1340.
Synthesis of complexes with ligand 1 (general procedure).
Compound 1 (1 equiv.) was dissolved in a minimum amount of
methanol on heating, and a solution of a metal salt (2 equiv.) in
methanol and triethylamine (2 equiv.) were added. The reaction
mixture was refluxed for 3—5 h. The crystals that precipitated
were filtered off, washed with MeOH and diethyl ether, and
dried in air.
[2,2´ꢀDi(2ꢀhydroxybenzaliminoethyl) disulfide]dinuckel(II)
dichloride (3). Complex 3 (0.05 g, 42%) was synthesized
from compound 1 (0.08 g, 0.2 mmol), NiCl2•6H2O (0.11 g,
0.4 mmol), and triethylamine (0.06 mL, 0.05 g, 0.4 mmol).
Green powder, m.p. 170 °C (with decomp.). Found (%):
С, 39.75; H, 3.33; N, 5.23. C18H18Cl2N2Ni2O2S2. Calcuꢀ
lated (%): С, 39.54; H, 3.32; N, 5.12. IR, ν/cm–1: 1620 (С=N);
1545, 1475, 1460, 1380, 1335.
[2,2´ꢀDi(2ꢀhydroxybenzaliminoethyl) disulfide]dicobalt(II)
dichloride (4). Complex 4 (0.24 g, 80%) was synthesized
from compound 1 (0.2 g, 0.55 mmol), CoCl2•6H2O (0.26 g,
1.1 mmol), and triethylamine (0.15 mL, 0.11 g, 1.1 mmol).
Dark brown powder, m.p. 180 °C (with decomp.). Found (%):
С, 39.41; H, 3.57; N, 5.16. C18H18Cl2Co2N2O2S2. Calcuꢀ
lated (%): С, 39.51; H, 3.32; N, 5.12. IR, ν/cm–1: 1620 (С=N);
1600, 1545, 1455, 1380, 1350, 1320.
IR, ν/cm–1: 1635, 1620 (C=N); 1600, 1540, 1470, 1455, 1380,
1350, 1325.
Bis{2ꢀ[(2ꢀthioethyl)iminomethyl]phenoxy}dicopper(II) (8).
Complex 8 (0.18 g, 42%) was synthesized in the reaction with
Cu(OAc)2•H2O (0.35 g, 1.76 mmol). Black powder, m.p.
>300 °C. Found (%): С, 44.50; H, 3.75; N, 5.87.
C
18H18Сu2N2O2S2. Calculated (%): С, 44.52; H, 3.74; N, 5.77.
IR, ν/cm–1: 1630, 1620 (C=N); 1600, 1540, 1500, 1470, 1455,
1400, 1380, 1355, 1330.
Di(2ꢀbenzalimino)diethyl disulfide (9). A solution of potasꢀ
sium hydroxide (0.26 g, 4.6 mmol) in a minimum amount of
boiling ethanol was added to a solution of cystamine (2 g,
2.3 mmol) in ethanol (10 mL). The reaction mixture was stirred
on heating for 1 h. After the reaction mixture was cooled to
~20 °C, the flakes were separated by filtration, benzaldehyde
(0.5 g, 0.48 mL, 4.6 mmol) was added with stirring to the resultꢀ
ing solution, and the mixture was stirred for 12 h. The solvent
was removed on a rotary evaporator. An oil was formed and
added with CHCl3 (10 mL), and an orange powder that formed
was filtered off and dried in air. The yield was 0.3 g (40%).
Found (%): С, 65.50; H, 6.05; N, 8.87. C18H20N2S2. Calcuꢀ
lated (%): С, 65.81; H, 6.14; N, 8.52. 1H NMR, δ: 8.33 (s, 2 Н,
НС=N); 8.13 (d, 1 Н, Ar, J = 7.4 Hz); 7.91 (d, 1 H, Ar, J =
7.0 Hz); 7.75 (d+t, 4 Н, Ar); 7.65 (t, 1 Н, Ar, J = 7.4 Hz); 7.56
(t, 1 Н, Ar, J = 7.6 Hz); 7.45 (d, 2 Н, Ar); 3.97, 3.10 (both t,
4 Н each, CH2, J = 6.65 Hz).
References
[2,2´ꢀDi(2ꢀhydroxybenzaliminoethyl) disulfide]dicopper(II)
dichloride (5). Complex 5 (0.33 g, 96%) was synthesized from
compound 1 (0.2 g, 0.55 mmol), CuCl2•2H2O (0.27 g,
1.1 mmol), and triethylamine (0.15 mL, 0.11 g, 1.1 mmol).
Green powder, m.p. 142 °C (with decomp.). Found (%):
С, 38.06; H, 3.86; N, 5.46. C18H18Cl2Cu2N2O2S2. Calcuꢀ
lated (%): С, 38.85; H, 3.26; N, 5.03. IR, ν/cm–1: 1620 (С=N);
1600, 1545, 1475, 1460, 1400, 1380, 1355, 1340.
Complexes 6—8 (general procedure). Potassium hydroxide
(0.098 g, 1.76 mmol) was dissolved in a minimum amount of
ethanol on heating and added to a solution of 2ꢀaminoethanethiol
hydrochloride (0.2 g, 1.76 mmol) in ethanol (2 mL). The reacꢀ
tion mixture was stirred on heating for 1 h until white flakes of
potassium chloride stopped precipitating. The KCl precipitate
was separated by filtration. Salicylaldehyde (0.185 mL, 0.22 g,
1.76 mmol) was added to the resulting solution, and in the
reactions with metal chlorides triethylamine (0.18 g, 0.24 mL,
1.76 mmol) was additionally added. The reaction mixture was
refluxed for 3.5 h. The precipitate that formed was filtered off,
washed with diethyl ether, and dried in air.
Bis{2ꢀ[(2ꢀthioethyl)iminomethyl]phenoxy}dinickel(II) (6). In
the reaction with NiCl2•6H2O (0.42 g, 1.76 mmol) the yield of
complex 6 was 0.27 g (64%), whereas in the reaction with
Ni(OAc)2•4H2O (0.44 g, 1.76 mmol) the yield was 0.25 g (52%).
Brown powder, m.p. >300 °C. Found (%): С, 44.24; H, 4.06;
N, 6.00. C18H18N2Ni2O2S2. Calculated (%): С, 45.43, H, 3.79;
N, 5.89. IR, ν/cm–1: 1620 (C=N); 1590, 1520, 1465, 1445,
1400, 1380, 1350, 1310.
Bis{2ꢀ[(2ꢀthioethyl)iminomethyl]phenoxy}dicobalt(II) (7).
Complex 7 (0.28 g, 64%) was synthesized in the reaction with
Co(OAc)2•4H2O salt (0.44 g, 1.76 mmol). Dark brown powꢀ
der, m.p. >300 °C. Found (%): С, 44.90; H, 3.92; N, 5.98.
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C
18H18Со2N2O2S2. Calculated (%): С, 45.43; H, 3.79; N, 5.89.
Received December 8, 2006