Novel copper(II) and cobalt(II) complexes with selenium substituted imidazolyl imines. the molecular and crystal structure of [N-(2-(phenylseleno) ethyl)-N-(imidazol-2-ylmethylene)amine]copper(II) dichloride

Article abstract of DOI:10.1016/j.poly.2012.11.039

A series of copper(II) and cobalt(II) complexes with novel selenium containing Schiff base ligands obtained from 2- or 3-aminoalkyl phenyl selenides and imidazole carbaldehydes have been synthesized by the interaction of corresponding organic ligands with MCl₂·6H₂O (M = Cu, Co). The crystal structure of a copper(II) complex with N-(2-(phenylseleno) ethyl)-N-(imidazolyl-2-ylmethylene)amine has been solved by a single-crystal X-ray diffraction method. The copper(II) ions are coordinated by the imine and imidazole nitrogen atoms of organic ligands and two chloride anions in a distorted square planar geometry. The electrochemical investigations of the synthesized ligands and complexes have been made by cyclic voltammetry method. It is established that the first stage of complexes reduction takes place to metal and the reduced forms of complexes are stable in the solution.

Full text of DOI:10.1016/j.poly.2012.11.039

Polyhedron 50 (2013) 425–433
Contents lists available at SciVerse ScienceDirect
Polyhedron
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Novel copper(II) and cobalt(II) complexes with selenium substituted imidazolyl
imines. The molecular and crystal structure of [N-(2-(phenylseleno)ethyl)-
N-(imidazol-2-ylmethylene)amine]copper(II) dichloride
⇑
Elena K. Beloglazkina , Alexander G. Majouga, Roman L. Antipin, Kseniya A. Myannik, Anna A. Moiseeva,
Nikolai V. Zyk
M.V. Lomonosov Moscow State University, Chemistry Department, Moscow 119992, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of copper(II) and cobalt(II) complexes with novel selenium containing Schiff base ligands
obtained from 2- or 3-aminoalkyl phenyl selenides and imidazole carbaldehydes have been synthesized
by the interaction of corresponding organic ligands with MCl2ꢀ6H2O (M = Cu, Co). The crystal structure of
Received 15 October 2012
Accepted 29 November 2012
Available online 8 December 2012
a
copper(II) complex with N-(2-(phenylseleno)ethyl)-N-(imidazolyl-2-ylmethylene)amine has been
solved by a single-crystal X-ray diffraction method. The copper(II) ions are coordinated by the imine
and imidazole nitrogen atoms of organic ligands and two chloride anions in a distorted square planar
geometry. The electrochemical investigations of the synthesized ligands and complexes have been made
by cyclic voltammetry method. It is established that the first stage of complexes reduction takes place to
metal and the reduced forms of complexes are stable in the solution.
Keywords:
Copper(II) and cobalt(II) complexes
X-ray crystal structure
Cyclic voltammetry
Semi-empirical calculations
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
possibility to coordinate metals of various nature and oxidation
state or to accomplish competing coordination of a certain metal
Organoselenium compounds represent an important class of
biologically active compounds. Selenium deficiency in human body
was found to increase the probability of cardio-vascular patholo-
gies, cancer, and arthritis [1–3]. The occurrence of selenium as an
integral component of a few redox-type enzymes in prokaryotes
has been known for several years, but until recently the only
known example in eukaryotes was glutathione peroxidase [4]
which can effectively reduce organic peroxides and thus protect
cells from damage due to reactive oxygen species. The ability of
this peroxidase to provided an explanation at the biochemical level
for the requirement of selenium as an essential trace element in
mammals and birds. The discovery during the past year provides
examples of an even more ubiquitous role of the element, namely
in growth and developmental processes of diverse animal species
including amphibian, and the plasma selenoprotein P with the
fundamental physiological importance [5–8].
atom. Such complexes can be used as cytostatic agents [9]. It is
shown that intramolecular interactions Se–N play an important role
in the antioxidant activity of these compounds [10]. In view of the
recent increased interest in effects of selenium as well as exciting
new developments at the basic biochemical level, rapid expansion
of our understanding of the roles of this trace element in biology
can be expected [5].
In recent publications we have described a series of new sulfur-
and seleno-substituted Schiff base ligands derived from 2- or 3-ami-
noalkyl phenyl selenides and 2-pyridine carbaldehyde [11] and their
coordination compound with Co(II) and Cu(II) [12]. In this work we
describe the synthesis of novel selenium containing organic ligands
N-(
x
-phenylseleno)ethyl)-N-(imidazolylmethylene)amines,
and
the results of their reactions with copper(II) and cobalt(II) chloride.
2. Experimental
High biological activity made selenium-containing organic com-
pounds an attractive class of ligands for studying of coordination
properties in the reactions with transition metals. Low-molecular
organic ligands containing both selenium and nitrogen atoms are
of special interest, since the presence of a powerful electron-donat-
ing nitrogen atom and weakly donating selenium atom gives them a
2.1. General
Diphenyl diselenide and imidazole carbaldehydes were obtained
from commercial sources and used as received. 2-(Phenylsele-
no)ethyl amine hydrochloride (1) and 3-(Phenylseleno)propyl
amine hydrochloride (2) were obtained according to the procedures
described earlier [13]. The melting points are uncorrected. 1H NMR
spectra were recorded on a Varian-XR-400 recorder (400 MHz for
⇑
Corresponding author. Tel.: +7 4953168202.
E-mail address: bel@org.chem.msu.ru (E.K. Beloglazkina).
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.11.039

426
E.K. Beloglazkina et al. / Polyhedron 50 (2013) 425–433
1H and 100 MHz for 13C). The IR spectra in Nujol (for solids) or film
(for oils) were recorded on a Perkin-Elmer 1430 spectrophotometer.
Electronic spectra in 10ꢁ3 mol Lꢁ1 CH3CN solution were obtained on
a Perkin–Elmer Lambda 35 UV–Vis spectrophotometer. Mass spec-
tra with laser ionization were recorded on a Autoflex II Bruker
mass-spectrometer (resolution FWHM 18000, nitrogen laser with
k = 337 nm, time-of-flight mass-spectrometer, potential accelerat-
ing 20 kV, recording of spectra in positive ions mode; the samples
were applied to polished steel plate; the resulting spectra were the
sum of 300 spectra, obtaining in different regions of a sample). Elec-
trochemical studies were carried out on a PI-50-1.1 potentiostat.
Glassy-carbon disk (2 mm in diameter) was used as the working
electrodes; a 0.05 M Bu4NClO4 solution in DMF served as the sup-
porting electrolyte; Ag/AgCl/KCl(sat.) was used as the reference
electrode. All measurements were carried out under argon; the sam-
ples were dissolved in the pre-deaerated solvent. Dimethylformam-
ide (high-purity grade) was purified by successive refluxing and
vacuum distillation over anhydrous CuSO4 and P2O5.
1H, Im), 3.9 (s, 3H, CH3), 3.67 (t, 2H, CH2N, J = 7.3 Hz), 3.00 (t, 2H,
CH2Se, J = 7.3 Hz), 2.07 (m, 2H, CH2). 13C NMR (CDCl3): 153.6,
143.0, 132.5, 130.2, 129.1, 126.7, 124.7, 61.1, 35.3, 31.3, 25.4. IR,
m
/cmꢁ1: 1655, 1580, 1490. MS (m/z): 308 (M+).
2.2.6. N-(2-(Phenylseleno)ethyl)-N-(imidazol-4-ylmethylene)amine
(7)
Brown powder (0.283 g, 60%). M.p. 146–147 °C. 1H NMR
(CDCl3): 8.12 (s, 1H, HC@N), 7.86 (m, 2H, Ph), 7.74(b.s., 2H, Im),
7.48 (v, 3H, Pn) 3.92 (m, 2H, CH2N), 3.26 (m, 2H, CH2Se). 13C
NMR (CDCl3): 154.0, 137.5, 134.4, 132.7, 129.7, 129.1, 127.0,
125.7, 60.7, 28.4. IR, m
/cmꢁ1: 1650, 1580, 2970. MS (m/z): 279 (M+).
2.2.7. N-(3-(Phenylseleno)propyl)-N-(imidazol-4-ylmethylene)amine
(8)
Brown oil (0.300 g, 62%). 1H NMR (CDCl3): 8.25 (s, 1H, HC@N),
7.73 (b.s., 2H, Im), 7.48 (d, J = 7.3 Uw, 2H, Ph), 7.24 (m, 3H, Ph),
3.72 (m, 2H, CH2N), 2.94 (m, 2H, CH2Se), 2.06 (m, 2H, CH2). 13C
NMR (CDCl3): 152.1, 139.5, 137.5, 132.7, 129.1, 129.9, 126.9,
PM3 calculation were performed by use the HYPERCHEM software
on PC. Geometry optimization of the molecules was carried out
127.2, 59.8, 31.0, 25.2. IR,
m
/cmꢁ1: 1655, 1580, 1480. MS (m/z):
with
a gradient less than 0.01 kcal/mol as the convergence
293 (M+).
criterion.
2.2.8. N-(2-(Phenylseleno)ethyl)-N-(5-methyl-imidazol-4-ylmethyl
ene)amine (9)
2.2. Synthesis of organic ligands
Yellow oil (0.421 g, 85%). 1H NMR (CDCl3): 8.10 (s, 1H, HC@N),
7.63 (s, 1H, Im), 7.52 (m, 3H, Ph) 7.29 (m, 2H, Ph), 3.9 (t, 2H,
CH2N, J = 6.7 Hz), 3.23 (t, 2H, CH2Se, J = 6.7 Hz), 2.41 (s, 3H, CH3).
13C NMR (CDCl3): 154.1, 142.2, 132.0, 129.9, 129.6, 126.3, 122.5,
2.2.1. Selenium-substituted imines 3–10 (typical procedure)
Solution of KOH (0.09 g, 1.7 mmol) in minimal amount of EtOH
was added to an equimolar amount of the stirred solution of com-
pound 1 or 2 in 5 ml of EtOH. After a complete precipitation of
white flakes of KCl the solid was filtered off and equimolar amount
of aldehyde in EtOH was added to the resulting solution. The mix-
ture was boiled for 7 h, then the solvent was removed in reduced
pressure and the resulting solid or oil was recrystallized from EtOH
of purified by flash chromatography (SiO2, ligroin).
61.1, 28.2, 20.5. IR, m
/cmꢁ1: 1640, 1580, 2990. MS (m/z): 293 (M+).
2.2.9. N-(3-(Phenylseleno)propyl)-N-(5-methyl-imidazol-4-ylmethyl
ene)amine (10)
Yellow-orange oil (0.283 g, 60%). 1H NMR (CDCl3): 8.20 (s, 1H,
HC@N), 7.59 (s, 1H, Im), 7.46 (m, 2H, Ph), 7.22 (dd, 3H, Ar,
J1 = 1.6 Hz, J2 = 7.4 Hz), 3.68 (m, 2H, CH2N), 2.95 (m, 2H, CH2Se),
2.37 (s, 3H, CH3), 2.05 (m, 2H, CH2). 13C NMR (CDCl3): 151.2,
149.2, 138.5, 132.8, 130.9, 129.1, 127.1, 59.3, 50.0, 28.0, 12.6. IR,
2.2.2. N-(2-(Phenylseleno)ethyl)-N-(imidazol-2-ylmethylene)amine
(3)
Brown powder (0.283 g, 60%). M.p. 149–150 °C. 1H NMR
(CDCl3): 8.19 (s, 1H, HC@N), 7.53 (m, 2H, Ph), 7.27 (m, 3H, Ph),
7.08 (b.s., 2H, Im), 3.92 (t, 2H, CH2N, J = 6.8 Hz), 3.21 (t, 2H, CH2Se,
J = 6.8 Hz). 13C NMR (CDCl3): 153.6, 143.9, 131.8, 129.7, 129.6,
m
/cmꢁ1: 1655, 1585, 1455. MS (m/z): 307 (M+).
2.3. Synthesis of copper(II) and cobalt(II) complexes
129.8, 127.0, 125.4, 60.3, 28.0. IR,
m
/cmꢁ1: 2940, 1650, 1500,
2.3.1. Synthesis of coordination compounds 11–26 (typical procedure)
Concentrated solutions of ligand 3–10 (0.05 g) in 1–2 ml of CH2-
1520. MS (m/z): 279 (M+).
.
Cl2 and equimolar amount of MCl2 6H2O (M = Cu, Co) in 1–2 ml of
2.2.3. N-(3-(Phenylseleno)propyl)-N-(imidazol-2-ylmethylene)amine
(4)
EtOH were mixed at room temperature and stand to the complex
precipitation. The forming solid was filtered off, washed by small
portions of Et2O and dried in air.
Light-brown oil (0.471 g, 95%). 1H NMR (CDCl3): 8.16 (s, 1H,
HC@N), 7.53 (d, 2H, Ph, J = 7.3 Hz), 7.24 (m, 4H, Im + Ph), 6.80
(b.s., 1H, Im), 3.68 (t, 2H, CH2N, J = 6.3 Hz), 2.94 (t, 2H, CH2Se,
J = 6.3 Hz), 2.12 (m, 2H,CH2). 13C NMR (CDCl3): 153.3, 143.0,
2.3.2. [N-(2-(Phenylseleno)ethyl)-N-(imidazol-2-ylmethylene)
amine]copper(II) dichloride (11)
133.5, 130.6, 129.8, 129.6, 127.7, 125.8, 60.3, 31.1, 22.2. IR,
m
/
Dark-green powder (0.040 g, 55%). M.p. 168–169 °C. IR, m :
/cmꢁ1
cmꢁ1: 2980, 1655, 1585, 1495. MS (m/z): 293 (M+).
1640, 1585, 1470. MS (m/z): 377 ([MꢁCl]+). Anal. Calc. for C12H13-
Cl2CuN3Se: C, 34.93; H, 3.18; N, 10.18. Found: C, 34.70; H, 3.33;
N, 10.56%.
2.2.4. N-(2-(Phenylseleno)ethyl)-N-(1-methyl-imidazol-2-ylmethylene)
amine (5)
Yellow oil (0.446 g, 90%). 1H NMR (CDCl3): 8.17 (s, 1H, HC@N),
7.55 (m, 2H, Ph), 7.32 (v, 3H, P), 7.12 (b.s., 1H, Im), 6.94 (b.s., 1H,
Im), 3.43 (m, 2H, NCH2), 3.64 (s, 3H, CH3), 3.01 (m, 2H, SeCH2).
13C NMR (CDCl3): 154.1, 142.8, 132.8, 129.9, 129.2, 129.0, 126.8,
2.3.3. [N-(2-(Phenylseleno)ethyl)-N-(imidazol-2-ylmethylene)
amine]cobalt(II) dichloride (12)
Dark-blue powder (0.029 g, 40%). M.p. 110–111 °C. IR, m :
/cmꢁ1
1600, 1520, 1470. UV–Vis, kmax, nm (e
, L molꢁ1 cmꢁ1) (CH3CN):
124.8, 61.5, 35.3, 28.7. IR,
m
/cmꢁ1: 1655, 1580, 1490. MS (m/z):
344 (5020), 718 (115). MS (m/z): 408 (M+). Anal. Calc. for C12H13Cl2-
293 (M+).
CoN3Se:C, 35.32; H, 3.21; N, 10.30. Found: C, 34.90; H, 3.08; N, 9.97%.
2.2.5. N-(3-(Phenylseleno)propyl)-N-(1-methyl-imidazol-2-ylmethyle
ne) amine (6)
2.3.4. [N-(3-(Phenylseleno)propyl)-N-(imidazol-2-ylmethylene)amine]
copper(II) dichloride (13)
Yellow oil (0.448 g, 90%). 1H NMR (CDCl3): 8,32 (s, 1H, HC@N),
7.51 (m, 2H, Ph), 7.23 (m, 3H, Ph), 7.11 (b.s., 1H, Im), 6.92 (b.s.,
Dark-green powder (0.043 g, 59%). M.p. 121–122 °C. IR, m :
/cmꢁ1
1644, 1580, 1473. MS (m/z): 391 ([MꢁCl]+). Anal. Calc. for C13H15-

E.K. Beloglazkina et al. / Polyhedron 50 (2013) 425–433
427
Cl2CuN3Se: C, 36.59; H, 3.54; N, 9.85. Found: C, 35.99; H, 3.51; N,
2.3.13. [N-(3-(Phenylseleno)propyl)-N-(imidazol-4-ylmethylene)
9.49%.
amine]cobalt(II) dichloride (22)
Dark-green powder (0.037 g, 52%). M.p. 178–180 °C. IR,
m
/cmꢁ1
e
, L molꢁ1 cmꢁ1) (CH3CN): 280
:
1640, 1587, 1575. UV–Vis, kmax, nm (
2.3.5. [N-(3-(Phenylseleno)propyl)-N-(imidazol-2-ylmethylene)
amine]cobalt(II) dichloride (14)
(1080), 743 (600). MS (m/z): 387 ([MꢁCl]+). ]+). Anal. Calc. for C13-
H15Cl2CoN3Se: C, 36.99; H, 3.58; N, 9.96. Found: C, 36.79; H, 3.47;
N, 9.71%.
Dark-green powder (0.039 g, 55%). M.p. 170–171 °C. IR,
m
/cmꢁ1
e
, L molꢁ1 cmꢁ1) (CH3CN): 244
:
1650, 1610, 1635. UV–Vis, kmax, nm (
(2630), 620 (120). MS (m/z): 387 ([MꢁCl]+). Anal. Calc. for C13H15-
Cl2CoN3Se: C, 36.99; H, 3.58; N, 9.96. Found: C, 36.92; H, 3.50; N,
9.89%.
2.3.14. [N-(2-(Phenylseleno)ethyl)-N-(5-methyl-imidazol-4-ylmethyl
ene)amine]copper(II) dichloride (23)
Green powder (0.044 g, 61%). M.p. 170–171 °C. IR,
m
/cmꢁ1
e
, L molꢁ1 cmꢁ1) (CH3CN):
:
1678, 1600, 1554. UV–Vis, kmax, nm (
2.3.6. [N-(2-(Phenylseleno)ethyl)-N-(1-methyl-imidazol-2-ylmethy
lene)amine]copper(II) dichloride (15)
Light-green powder (0.039 g, 55%). M.p. 146–147 °C. IR,
1625, 1580, 1545. UV–Vis, kmax, nm (
269 (3990), 700 (100). MS (m/z): 391 ([MꢁCl]+). Anal. Calc. for C13-
H15Cl2CuN3Se: C, 36.59; H, 3.54; N, 9.85. Found: C, 36.52; H, 3.43;
N, 9.75%.
m :
/cmꢁ1
e
, L molꢁ1 cmꢁ1) (CH3CN):
344.0 (14 315), 398.0 (15 030), 736.0 (600). MS (m/z): 391
([MꢁCl]+). Anal. Calc. for C13H15Cl2CuN3Se: C, 36.59; H, 3.54; N,
9.85. Found: C, 36.80; H, 3.66; N, 10.00%.
2.3.15. [N-(2-(Phenylseleno)ethyl)-N-(5-methyl-imidazol-4-ylmethyl
ene)amine]cobalt(II) dichloride (24)
Green powder (0.035 g, 49%). M.p. 165 °C. IR,
m
/cmꢁ1: 1622,
1580. UV–Vis, kmax, nm (e
, L molꢁ1 cmꢁ1) (CH3CN): 261 (447),
2.3.7. [N-(2-(Phenylseleno)ethyl)-N-(1-methyl-imidazol-2-
ylmethylene)amine]cobalt(II) dichloride (16)
298 (3260), 755 (150). MS (m/z): 387 ([MꢁCl]+). ]+). Anal. Calc.
for C13H15Cl2CoN3Se: C, 36.99; H, 3.58; N, 9.96. Found: C, 36.63;
H, 3.41; N, 9.79%.
Dark-green powder (0.032 g, 45%). M.p. 111–112 °C. IR,
m
/cmꢁ1
e
, L molꢁ1 cmꢁ1) (CH3CN): 288
:
1620, 1580, 1472. UV–Vis, kmax, nm (
(1325), 570 (150). MS (m/z): 387 ([MꢁCl]+). Anal. Calc. for C13H15-
Cl2CoN3Se: C, 36.99; H, 3.58; N, 9.96. Found: C, 36.77; H, 3.80; N,
9.70%.
2.3.16. [N-(3-(Phenylseleno)propyl)-N-(5-methyl-imidazol-4-ylmeth
ylene)amine]copper(II) dichloride (25)
Dark-green powder (0.047 g, 65%). M.p. 115–116 °C. IR,
m
/cmꢁ1
e
, L molꢁ1 cmꢁ1) (CH3CN): 250
:
1635, 1588, 1475. UV–Vis, kmax, nm (
2.3.8. [N-(3-(Phenylseleno)propyl)-N-(1-methyl-imidazol-2-
ylmethylene)amine]copper(II) dichloride (17)
(8700), 701 (100). MS (m/z): 405 ([MꢁCl]+). Anal. Calc. for C14H17-
Cl2CuN3Se: C, 38.15; H, 3.89; N, 9.53. Found: C, 37.96; H, 3.85; N,
9.50%.
Green powder (0.031 g, 43%). M.p. 165 °C. IR,
m
/cmꢁ1: 1642,
1520, 1475. UV–Vis, kmax, nm (e
, L molꢁ1 cmꢁ1) (CH3CN): 204
(1585), 264 (980), 300 (905), 743 (200). MS (m/z): 405 ([MꢁCl]+).
2.3.17. [N-(3-(Phenylseleno)propyl)-N-(5-methyl-imidazol-4-ylmeth
ylene)amine]cobalt(II) dichloride (26)
2.3.9. [N-(3-(Phenylseleno)propyl)-N-(1-methyl-imidazol-2-
Green powder (0.035 g, 49%). M.p. 149–150 °C. IR,
m
/cmꢁ1
e
, L.molꢁ1 cmꢁ1) (CH3CN):
:
ylmethylene)amine]cobalt(II) dichloride (18)
Green powder (0.017 g, 25%). M.p. 99–100 °C. IR, m
/cmꢁ1: 1650,
1635, 1610, 1470. UV–Vis, kmax, nm (
234 (9920), 720 (120). MS (m/z): 401 ([MꢁCl]+). Anal. Calc. for C14-
H17Cl2CoN3Se: C, 38.56; H, 3.93; N, 9.64. Found: C, 38.19; H, 3.44;
N, 9.41%.
1585, 1490. UV–Vis, kmax, nm (e
, L molꢁ1 cmꢁ1) (CH3CN): 230
(1120), 523 (150). MS (m/z): 401 ([MꢁCl]+). Anal. Calc. for C14H17-
Cl2CoN3Se: C, 38.56; H, 3.93; N, 9.64. Found: C, 38.38; H, 3.52; N,
9.38%.
2.3.18. [N-(2-(Phenylseleno)ethyl)-N-(imidazol-2-ylmethylene)amine]
copper(I) chloride (27)
2.3.10. [N-(2-(Phenylseleno)ethyl)-N-(imidazol-4-ylmethylene)
amine]copper(II) dichloride (19)
A solution of Cu(MeCN)4ClO4 (0.058 g, 0.1 mmol) and benzyl tri-
ethyl ammonium chloride (0.022 g, 0.1 mmol) in 3 ml of CH3CN
was slowly added to the solution of ligand 11 (0.028 g, 0.1 mmol)
in 3 ml of CH3Cl, and the reaction mixture, placed in an open
test-tube, was left at room temperature at a tightly capped vessel
containing 10 ml of diethyl ether. After three days the forming so-
lid of compound 27 was separated by centrifugation and dried in
air. Olive green powder (0.012 g, 30%). M.p. 160–161 °C. MS (m/
z): 342 ([MꢁCl]+).
Light-blue powder (0.035 g, 48%). M.p. 140–141 °C. IR,
m
/cmꢁ1
e
, L.molꢁ1.cmꢁ1) (CH3CN):
:
1679, 1640, 1580. UV–Vis, kmax, nm (
262 (5540), 707(140). MS (m/z): 377 ([MꢁCl]+). Anal. Calc. for C12-
H13Cl2CuN3Se: C, 34.93; H, 3.18; N, 10.18. Found: C, 34.85; H, 3.12;
N, 10.39%.
2.3.11. [N-(2-(Phenylseleno)ethyl)-N-(imidazol-4-ylmethylene)
amine]cobalt(II) dichloride (20)
Green powder (0.036 g, 50%). M.p. 178–180 oC. IR,
m
/cmꢁ1
:
1640, 1587, 1575. UV–Vis, kmax, nm (
e
, L molꢁ1 cmꢁ1) (CH3CN):
3. Results and discussion
344 (14 314), 398 (15 031), 736 (600). MS (m/z): 373 ([MꢁCl]+).
Anal. Calc. for C12H13Cl2CoN3Se: C, 35.32; H, 3.21; N, 10.30. Found:
C, 34.96; H, 3.18; N, 10.08%.
3.1. Synthesis of ligand and complexes
Selenium-substituted imines 3–10 were synthesized by the
condensation reactions of 2- or 4-imidazole carbaldehydes with
amino selenides 1 or 2 in EtOH (Scheme 1). According to NMR
spectra data, all Schiff bases 3–10 were isolated as single geometric
isomers, which were identified as the anti-isomers basing on the
results of NOE experiment performed on the example of compound
5 (NOE with the 1.5% intensity is observed for the protons of CH2N
groups (3.43 ppm) under the irradiation of HC@N protons
2.3.12. [N-(3-(Phenylseleno)propyl)-N-(imidazol-4-ylmethylene)
amine]copper(II) dichloride (21)
Dark-green powder (0.021 g, 30%). M.p. 170 °C. IR,
m
/cmꢁ1
e
, L molꢁ1 cmꢁ1) (CH3CN): 209
:
1640, 1475. UV–Vis, kmax, nm (
(1820), 734 (150). MS (m/z): 391 ([MꢁCl]+). Anal. Calc. for C13H15-
Cl2CuN3Se: C, 36.59; H, 3.54; N, 9.85. Found: C, 36.28; H, 3.41; N,
9.55%.

428
E.K. Beloglazkina et al. / Polyhedron 50 (2013) 425–433
Table 1
( )n
SePh
Crystal data and structure refinement for 11.a
N
CHO
N
R
R
R
EtOH
( )n
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
C12H13Cl2CuN3Se
412.65
100(2)
0.71073
monoclinic
C2/c
N
N
t oC
N
+
H2N
SePh
3, R = H, n = 1, 60%
4, R = H, n = 2, 95%
5, R = CH3, n = 1, 90%
6, R = CH3, n = 2, 95%
1, n = 1
2, n = 2
R = H, CH3
29.0194(14)
( )n
SePh
b (Å)
15.8127(8)
c (Å)
7.1159(3)
N
CHO
a
(°)
b (°)
(°)
90
R
EtOH
97.3990(10)
90
( )n
N
t oC
NH
c
N
+
H2N
SePh
NH
Volume (Å3)
3238.1(3)
7, R = H, n = 1, 85%
8, R = H, n = 2, 93%
9, R = CH3, n = 1, 80%
10, R = CH3, n = 2, 82%
Z
8
1, n = 1
2, n = 2
Dcalc (Mg/m3)
1.693
Absorption coefficient (mmꢁ1)
3.916
1624
F(000)
Crystal size (mm)
Theta range for data collection (°)
Index ranges
0.25 ꢂ 0.20 ꢂ 0.05
Scheme 1. Synthesis of ligands 3–10.
2.48–28.00
ꢁ38 6 h 6 38, 0 6 k 6 20,
0 6 l 6 9
3873
3873 [Rint = 0.0000]
98.8
semi-empirical from equivalents
0.823 and 0.440
full-matrix least-squares on F2
3873/0/176
Reflections collected
Independent reflections
Completeness to theta = 28.00° (%)
Absorption correction
Maximum and minimum transmissions
Refinement method
EtOH/CH2Cl2
.
MCl2 6H2O
LMCl2
11-26
L
+
3-10
M = Cu, Co
Scheme 2. Synthesis of complexes 11–26.
Data/restraints/parameters
Goodness-of-fit on F2
1.037
Final R indices [I > 2
R indices (all data)
Largest difference in peak and hole
(e Åꢁ3)
r
(I)]
R1 = 0.0441, wR2 = 0.1317
R1 = 0.0587, wR2 = 0.1390
1.126 and ꢁ0.897
(8.17 ppm)). Anti-configuration of ligand 3 was also confirmed by
the X-ray data for its copper complex 11 (see below).
IR spectra of all synthesized ligands display C@N and C@C
absorption bands in the region of 1450–1660 cmꢁ1. IR spectra of li-
gands 3, 4, 7, 8 show broad low-intensive band at 2900–3000 cmꢁ1
indicating the existence of hydrogen bond H–N, either intramolec-
ular (between imidazole NH protone and imino nitrogen atoms) or
intermolecular.
a
The solvent molecule (which is a superpositon of dichloromethane, ethanol and
diethyl ether) is disordered around an inversion center. Thereby, the contribution of
the solvent was removed from overall scattering by using PLATON
[18].
/SQUEEZE program
To obtain the coordination compounds, the ligand 3–10 solu-
tions in CH2Cl2 were mixed with eqimolar amount of CuCl2ꢀ6H2O
or CoCl2ꢀ6H2O solution in EtOH and the resulting mixture standing
to the solid precipitation. Complexes 11–26 (Scheme 2) with com-
position LꢀMCl2 (M = Cu, Co) were obtained in all cases (the collec-
tive designation «L» for organic ligands 3–10 will use below). All
complexes are reasonably soluble in CH3CN, DMF or DMSO.
IR spectra of complexes 11–26 show the shift of C@N and C@C
groups absorption bands at 1470–1680 cmꢁ1 compare to initial li-
gands which confirms the coordination of the metal ions with the
C@N nitrogen atoms.
Table 2
Selected bond lengths (Å) and angles (°) for 11.
Bond lengths
d (Å)
Bond angles
x (°)
Cu(1)–N(1)
Cu(1)–N(3)
Cu(1)–Cl(1)
Cu(1)–Cl(2)
N(3)–C(4)
C(1)–C(4)
N(1)–C(1)
N(1)–C(3)
C(2)–C(3)
N(2)–C(2)
N(2)–C(1)
1.973(3)
2.090(3)
2.2915(9)
2.2583(9)
1.278(5)
1.442(5)
1.321(4)
1.380(5)
1.373(5)
1.359(5)
1.343(5)
N(1)–Cu(1)–N(3)
N(1)–Cu(1)–Cl(1)
N(3)–Cu(1)–Cl(1)
N(1)–Cu(1)–Cl(2)
N(3)–Cu(1)–Cl(2)
Cl(2)–Cu(1)–Cl(1)
C(4)–N(3)–Cu(1)
C(1)–N(1)–Cu(1)
N(1)–C(1)–C(4)
C(4)–N(3)–C(5)
C(1)–N(1)–C(3)
80.32(12)
91.18(9)
170.49(9)
171.58(8)
93.61(9)
95.27(3)
112.4(2)
113.2(2)
118.3(3)
120.0(3)
106.6(3)
The electronic absorption spectra of complexes 11–26 display
weak d–d transition bands in the visible region at 520–755 nm
with e
= 100–600 L molꢁ1 cmꢁ1. According to literature, the square
planar compounds of Cu(II) possess a broad band in the 550–
750 nm region [14,15], which shows bathochromic shift upon
tetrahedral distortion [16]. The square planar cobalt complexes
normally have only one band in the visible region whereas three
bands at this area are commonly appeared for tetrahedral com-
plexes of Co(II) [17]. Thus, an observed pattern of the spectrum
and values of the molar absorption coefficient are typical for the
coordination compounds with the square planar or slightly tetra-
hedrally distorted ligand environment of the central ion Cu2+ or
Co2+. All complexes also have more strong charge transfer bands
in the UV region of their electronic spectra with the maximum at
204–398 nm.
diffractometer using graphite monochromated Mo K
( = 0.71 073 Å,
a
radiation
x
-scans) at 100 K. The structure was solved by direct
method and refined by the full-matrix least-squares against F2 in
anisotropic approximation for non-hydrogen atoms. Hydrogen
atoms were placed geometrically and refined in isotropic approxi-
mation in riding model. Crystallographic data and refinement
parameters for 11 are shown in Table 1, and selected bond lengths
are given in Table 2. Molecular structure of compound 11 together
with the atom numbering scheme is shown in Fig. 1. The crystals,
available for structural investigation, were made by slow diffusion
.
of diethyl ether to ethanolic solution of CuCl2 6H2O and ligand 11
(1:1). The coordination geometry of the copper(II) atom is nearly
square planar. The metal atom is surrounded by two chloride anions
and two nitrogen atoms of imidazole and imine fragments. Selenium
atom of ligand does not take part in the coordination of metal. The
3.1.1. Molecular and crystal structure of complex 11
The structure of complex 11 was established by X-ray diffraction.
Single crystal data for 11 were collected on a Bruker APEX2 DUO

E.K. Beloglazkina et al. / Polyhedron 50 (2013) 425–433
429
phenyl moiety and the selenium atom it is bound to are severely dis-
ordered by two positions. The 5-membered metallacycle Cu(1)–
N(3)–C(4)–C(1)–N(1) is practically planar.
In crystal structure of 11, isolated molecules are packed in lay-
ers parallel to each other and oriented toward the space diagonal
with respect to the unit cell (Fig. 2). The monomeric units of 11
are arranged in a chain-like fashion such that each copper ion is
coordinated additionally as axial ligands by two coordinated chlo-
ride of two neighboring monomeric units. These axial bonds are
however long (2.933(1) and 2.976(1) Å) and indicate a weak
interaction.
3.1.2. Electrochemistry
Some obtained ligands and complexes were studied by cyclic
voltammetry (CV) using a glass carbon (GC) electrode in DMF.
The electrochemical oxidation and reduction potentials are given
in Table 3.
Fig. 1. Molecular structure of complex 11. The minor component of the disordered
Ligands 3, 5, 6, 7 and 9 undergo a reduction at the potential
more negative than ꢁ1.7 V (see Table 3 and Fig. 3). Imidazoles 3,
5, 6, 7, 9 oxidize irreversible at the potentials 1.08–1.26 V. The
additional cathodic peaks at low potentials for complexes CV
curves (Figs. 3 and 4) correspond to reduction at the metal; the fol-
lowing cathodic peaks are due to reduction of the organic fragment
at more negative potentials that those for the free ligands.
The initial reduction of cobalt complex 12 occurs to metal at
ꢁ1.46 V. Note, that the reduced form of the complex is stable in
the solution which indicated by the absence of zerovalent metal
desorption peaks during the reverse anodic scans after the poten-
tial of ꢁ1.5 V, even when performing the electrolysis within 30 s.
Copper complexes 11, 15, 17, 19, 23 reduce at first stage quazy-
reversibly to metal at the anodic potential region (see Table 3 and
Figs. 3 and 4). The reduced form of complexes are stable at the time
scale of CVA method. The Cu(I) ? Cu(0) reductions peaks are ob-
served only for complexes 11, 17, 23. These peaks have very low
intensity, probably because of poor solubility characteristic for
copper(I) complexes [19–21].
Se-Ph fragment (with the occupancy ratio 0.559(8):0.441(8)) is not shown.
It should be especially note, that two peaks corresponding to
reduction Cu(II) ? Cu(I) at anodic potential region are observed
on CVA curves of synthesized complexes (Figs. 3 and 4). The inten-
sity of more anodic peak increases for second and the following
scans of CVA. These observations indicate the presence in the solu-
tion of two different complexes of copper(II) at one time.
This fact may be explained by the equilibrium of isomeric cop-
per complexes with the CuN2Cl2 and CuN2ClSe coordination
spheres, analogous to described in [22] for the N,N0,S,S0 scorpionate
ligands complexes. The proposed pattern of these equilibriums is
shown on Scheme 3. The reduction of original coordination com-
pounds may proceed with the removal of chloride anion resulting
in the formation of Cu(I)-containing intermediate A. This interme-
diate, having in the structure more soft copper(I) atom compare to
initial copper(II) complex, stabilizes by coordination with soft do-
nor, namely selenium atom of organic ligand, completing of coor-
dination sphere of copper ion with the formation of intermediate
B. The subsequent oxidation of B gives complex 11a, differing from
starting complex. Complex C may also be generated directly from
initial complex 11 as a result of intramolecular substitution of
chloride anion to selenium in copper coordination sphere.
To confirm this hypothesis, semi-empirical PM3 calculation for
complex 11, as well as species A, B and monocation 11a were per-
formed. The optimized structures are reported in Figs. 5 and 6. The
calculated structure of complex 11 is very much like to X-ray data
(square planar environment of copper coordination environment;
bond lengths and angles; see Fig. 5). The most significant difference
in the experimental and calculated structured of complex 11 is the
position of PhSe-groups: a plane of benzene ring in calculated
structure is practically perpendicular to imidazole fragment plane
Fig. 2. Fragment of the crystal packing of the compound 11 along the crystallo-
graphic axis c.

430
E.K. Beloglazkina et al. / Polyhedron 50 (2013) 425–433
Table 3
Electrochemical reduction potentials (ERed) and oxidation potentials (EOx) of the ligands 3, 5–7, 9 and their metal complexes
measured relative to Ag|AgCl|KCl(sat.) by the CV methods at a glassy-carbon electrode (DMF, 0.05 M Bu4NClO4, 200 mV sꢁ1). The
values after the slash marks represent the peak potentials for the reverse CV scans.
Red
Ox
Compound
Ep
Ep
1.08; 1.39
ꢁ1.77; ꢁ2.17; ꢁ2.37
3
N
Se Ph
H
N
N
+0.40/+0.52; +0.13/+0.52a; ꢁ0.78b; ꢁ2.03
1.23c
11
N
Se Ph
H
N
Cl
Cu
Cl
N
ꢁ1.46; ꢁ1.77; ꢁ2.06
1.16c
12
N
Se Ph
N
N
Cl
Co
Cl
ꢁ1.91; ꢁ2.40
1.26; 1.52
5
CH3
N
N
Se Ph
N
+0.44/+0.53; +0.14/+0.48a; ꢁ2.29
1.28
15
CH3
N
Se Ph
Se Ph
N
Cl
Cu
Cl
N
ꢁ2.25; ꢁ2.64
1.08; 1.20; 1.39
6
CH3
N
N
N
N
N
+0.40/+0.50; +0.06/+0.12a; ꢁ0.78b; ꢁ1.76; ꢁ2.11
1.16
17
CH3
N
Se Ph
Cl
Cu
Cl
ꢁ1.84; ꢁ2.38; ꢁ2.66
1.17
7
N
Se Ph
N
N
H
+0.38/+0.50; +0.10/+0.53a; ꢁ2.09; ꢁ2.48
1.16c
19
N
Se Ph
Cl
Cu
Cl
HN
N
ꢁ1.88; ꢁ2.37
1.14; 1.28
9
CH3
N
Se Ph
HN
N

E.K. Beloglazkina et al. / Polyhedron 50 (2013) 425–433
431
Table 3 (continued)
Compound
23
Red
Ox
Ep
Ep
1.17c
+0.36/+0.54; ꢁ0.09/+0.06a; ꢁ0.76b; ꢁ2.16
CH3
N
Se Ph
Cl
Cu
Cl
HN
N
a
b
c
The intensity of this peak increases under multiply potential scanning Cu(II) ꢀ Cu(I).
The reverse peak at ꢃ0 V corresponding to the desorption of Cu(0) is detected on CVA.
High-intensive peak corresponding to carrying at least three electrons.
N
H
Se Ph
Cl
Cl
N
CuI
Se Ph
H
N
+ e
N
CuII
N
- Cl-
N
Cl
11
A
+
N
CuII
Se Ph
N
Se Ph
H
- e
H
N
X-
N
CuI
X-
N
Cl
+
N
Cl
11a
B
Fig. 3. Cyclic voltammograms of ligand 6 (dashed line) and its copper complex 17
(solid line). DMF, 0.05 M Bu4NClO4, 10–3 M.
(X = Cl-, ClO4 )
-
Scheme 3. The proposed equilibriums between Cu-containing species in the
process of reduction and the following oxidation of complex 11.
Both structures A and B, according to calculation results, corre-
spond to the possible reduction intermediates. The calculated
heats of formation for species A and B are ꢁ55.52 and ꢁ60.11
kcal/mol, respectively. It appears that both A and B can exist in
the solution, but Se-coordinated form B is rather more stable.
As additional proof of the predominance of Se-coordinated cop-
per after the reduction of investigated complexes we also synthe-
sized the complex of ligand 11 with copper(I) by the interaction
of ligand 11 with Cu(MeCN)4ClO4 in the presence of equimolar
amount of benzyl triethyl ammonium chloride (Scheme 4). To pro-
pose a molecular geometry for the complex 27, PM3 calculation
were performed. The optimized structure is given in Fig. 6. In the
accordance with calculation results, copper(I) ion in complex 27
is located in a near square planar environment and bound with
one chlorine, one selenium and two nitrogen atoms (see Fig. 6).
The oxidation peaks for N-unsubstatued imidazoles complexes
11, 12, 19, 23 are high intensive, which may be explained by con-
temporary oxidation at the near potentials both organic ligand and
chloride anions.
Fig. 4. Cyclic voltammograms of complex 19: first scan (solid line); after the
multiply potential cycling Cu(II) ꢀ Cu(I) (dashed line).
4. Conclusion
whereas these cycles in actual structure are near coplanar. This dif-
In the conclusion, a series of mononuclear copper(II) and cobal-
t(II) complexes with novel organic ligands, forming as a result of
2- or 3-aminoalkyl phenyl selenides and imidazole carbaldehydes
interaction, have been prepared by the reactions of metal chloride
with ligand in EtOH/CH2Cl2 mixture. The complexes have been
characterized by IR, UV–vis spectroscopy and cyclic voltammetry.
The X-ray analysis of copper complex with 2-(phenylsele-
no)ethyl)-N-(imidazol-4-ylmethylene)amine revealed that the
copper(II) ion assumes a tetracoordinated square–planar geometry
with an N2Cl2 donor set.
ference is apparently due to the
p–p stacking of benzene rings of
neighbor ligand molecules in crystal structure, which do not take
into account at the calculations process. The similarity of
calculated complex 11 structure with X-ray data let we assume
that the calculations data are adequate characterize the copper
coordination geometry in the complexes under consideration. As
to monocation [11-Cl]+, in its optimized structure selenium atom
takes part in metal coordination with the formation of near square
planar copper ion coordination environment.

432
E.K. Beloglazkina et al. / Polyhedron 50 (2013) 425–433
Fig. 5. Comparison between the Cu(II) experimental geometry (X-ray) of the complex 11 (a) with the respective PM3-optimized species 11 (b) and monocation 11a (c).
in terms of formation of complexes with different composition
and geometry of copper coordination sphere.
Acknowledgment
We are grateful to the Russian Foundation of Basic Research
(Project 10-03-00677) for the financial support of this work.
Appendix A. Supplementary material
CCDC 898469 contains the supplementary crystallographic
data for complex 11. These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
Fig. 6. PM3-optimized structures of complex 27. Selected bond lendth and angles:
Cu-N(1) 1.878Å, Cu-N(3) 1.872Å, Cu-Cl 2.153Å, Cu-Se 2.211Å; N(1)-Cu(1)-N(3)
deposit@ccdc.cam.ac.uk.
90.88°; N(1)-Cu-Cl 94.81°; N(3)-Cu-Se 83.83°; Cl-Cu-Se 90.41°.
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