2
S. Sarkar et al. / Polyhedron 28 (2009) 1–6
using TMS as an internal standard in CDCl3. The room temperature
magnetic susceptibility measurements were performed by using a
vibrating sample magnetometer PAR 155 model. Molar conduc-
tance (KM) were measured in a systronics conductivity meter
304 model using ꢀ10ꢁ3 mol Lꢁ1 solutions in acetonitrile. The mea-
surement of pH of the reaction mixture was done with a systronics
digital pH meter (Model 335). The separation and detection of the
species in the reaction mixture were carried out using the hyphen-
ated GC–MS system (Schimadzu, model GCMS-QP5050A). Electro-
chemical measurements were recorded on a computer controlled
EG & G PAR model 270 VERSTAT electrochemical instruments
using Ag/AgCl electrodes with TBAP as supporting electrolyte. All
the measurements were made at 298 K with acetonitrile as solvent
for complexes 1 and 2 and dimethylformamide for 3, using a con-
centration ca. 10ꢁ3–10ꢁ4 M purged with dry nitrogen for 3–4 min
in order to remove dissolved oxygen.
2.4. Preparation of the copper(I) complex of 1,4-bis(2-
pyridylmethylthio)butane (4)
The solution of complex 3 in DMF was stirred for 1 h at room
temperature in presence of air. After few days, the colorless single
crystals of complex 4 were collected by slow evaporation of this
solution
[Cu2(L3)2](ClO4)2,0.5H2O (4): Anal. Calc. for C32H41Cl2Cu2-
N4O8.5S4: C, 40.68; H, 4.34; N, 5.93, Cu, 13.45. Found: C, 40.01; H,
4.21; N, 5.88; Cu, 13.34%. IR (cmꢁ1):
1092 and 623.
mC@N, 1479; mC–S, 758; mClO4,
2.5. X-ray crystal structure analysis
Single crystals suitable for X-ray diffraction analysis were
grown by slow evaporation of acetonitrile solutions of complex 1
and 2 at ambient temperature, while crystals of complex 4 were
obtained from dimethylformamide solution of copper(II) complex
3 by slow evaporation at room temperature in presence of air.
Crystal data and details of data collections and refinements for
the structures reported are summarized in Table 1. Diffraction data
of 1 and 2 were collected at 150(2) K on Oxford Diffraction X-Cal-
ibur CCD System, data collection of 4 were carried out, at room
2.2. Preparation of the ligands
The syntheses of the ligands were carried out following the
reported procedure [6] with slight modification.
A common
procedure has been performed to obtain the ligands. The procedure
for the preparation of 1,2-bis(2-pyridylmethylthio)ethane, (L1) is
here described. An ethanolic solution of 2-picolyl chloride,
hydrochloride (1.64 g, 10.0 mmol) was added to 1,2-ethandithiol
(0.47 g, 5.0 mmol) in dry ethanol containing sodium ethoxide
(0.46 g 20.0 mmol) at low temperature (0–5 °C). Then this mixture
was allowed to stir at room temperature for 0.5 h and then it was
refluxed for 2 h. The mixture was cooled to room temperature,
water was added and finally the ethanol was off by rotary
evaporator. The product was extracted into dichloromethane and
dried by using NaHSO3. The product, 1,2-bis(2-pyridylmethyl-
thio)ethane (L1) was obtained as a yellow oil by removing the
dichloromethane by rotary evaporator. The other products were
also obtained as liquids. Finally the products were verified by 1H
NMR spectroscopy.
temperature, on a Nonius DIP-1030H system, by using Mo Ka radi-
ation, k = 0.71073 Å in both cases. Cell refinement, indexing and
scaling of all the data sets were performed using programs Crys
Alis [7], Denzo and Scalepack [8]. All the structures were solved
by direct methods and subsequent Fourier analyses and refined
by the full-matrix least-squares method based on F2 with all ob-
served reflections [9]. A residual in the difference Fourier map of
4, located on a two-fold axis, was assigned to a water oxygen with
occupancy 0.25. The contribution of hydrogen atoms at calculated
positions were included in final cycles of refinement. All the calcu-
lations were performed using the WinGX System, Ver 1.70.01 [10].
3. Result and discussion
2.3. Preparation of the copper(II) complexes
3.1. Synthesis and characterization
The copper(II) complexes were synthesized following a com-
mon procedure as described below, using copper(II) perchlorate
hexahydrate and the respective organic compounds in equimolar
ratio. For complex 1, L1 (276.0 mg, 1.0 mmol), for complex 2, L2
(292.0 mg, 1.0 mmol) and for complex 3, L3 (306.0 mg, 1.0 mmol)
were mixed with 1.0 mmol of copper(II) perchlorate hexahydrate,
and the mixture was stirred for 4 h in methanol. Then sodium chlo-
ride (1.0 mmol) was added to the resulting mixture and stirred for
another 1 h at room temperature. The green coloured complexes
were precipitated out and the solid complexes were filtered,
washed with water, cold methanol and dried in vacuo. Yield:
84–85%.
The organic compounds (L) were synthesized by the reaction of
the respective alkyl dithiol compound with 2-picolyl chloride in
Table 1
Crystal data and details of refinements for 1, 2 and 4
1
2
4.0 ꢂ 5H2O
Empirical formula C14H16Cl2CuN2O4S2 C15H18Cl2CuN2O4S2 C32H41Cl2Cu2N4O8.5S4
Formula weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
474.85
triclinic
P
488.87
monoclinic
P21/a
8.5188(5)
24.783(3)
9.0438(12)
90.00
92.586(7)
90.00
1907.4(3)
4
943.91
orthorhombic
Iba2
20.331(4)
21.310(4)
9.988(3)
90.00
90.00
90.00
4327.3(18)
4
1.449
8.2345(9)
10.2758(10)
12.1620(11)
109.456(9)
96.603(8)
111.400(9)
870.03(15)
2
[Cu(L1)Cl]ClO4 (1): Anal. Calc. for C14H16Cl2CuN2O4S2: C, 35.37;
H, 3.37; N, 5.90, Cu, 13.37. Found: C, 35.52; H, 3.46; N, 5.74, Cu,
a
(°)
b (°)
(°)
13.21%. IR0020(cmꢁ1):
Magnetic moment (
m
C@N, 1476;
mC–S, 758; mClO , 1090 and 621.
4
ꢁ1 cm2
c
l
, B.M.): 1.81. Conductivity (Ko, X
Volume (Å3)
Z
molꢁ1) in acetonitrile: 145.
[Cu(L2)Cl]ClO4 (2): Anal. Calc. for C15H18Cl2CuN2O4S2: C, 36.82;
qcalc (g/cm3)
F(000)
1.813
482
1.702
996
H, 3.68; N, 5.73, Cu, 12.99. Found: C, 37.22; H, 3.77; N, 5.81, Cu,
1940
13.11%. IR (cmꢁ1):
m
C@N, 1465;
m
C–S, 758;
m
ClO4, 1088 and 624. Mag-
h Range (°)
2.74–30.00
2.40–30.00
1.668
2.97–25.02
1.349
ꢁ1 cm2 molꢁ1) in
l
(Mo Ka ) 1.825
) (mm-1
netic moment (l, B.M.): 1.79. Conductivity (Ko, X
Independent
4824
5519
3598
acetonitrile: 140.
reflections
[Cu2(L3)2Cl2](ClO4)2 (3): Anal. Calc. for C32H40Cl4Cu2N4O8S4: C,
Reflections with
3343
2129
2454
I > 2r(I)
38.18; H, 3.98; N, 5.57, Cu,12.63. Found: C, 37.82; H, 4.02; N,
5.79, Cu, 12.47%. IR (cmꢁ1):
m
C@N, 1478;
, B.M.): 1.45 per Cu atom. Conductivity
Ko, X
ꢁ1 cm2 molꢁ1) in DMF: 150.
mC–S, 760, mClO4, 1088 and
R1
wR2
Goodness-of-fit
0.0570
0.1469
1.028
0.0418
0.0760
0.764
0.0664
0.1728
0.975
622. Magnetic moment (
l
(