A.H. Kianfar et al. / Polyhedron 85 (2015) 488–492
489
3
Fig. 1. The structure of [Ni(Salen)], DDQ and [Ni(Salen)].DDH complexes.
2.2. Synthesis of Schiff base and nickel complex
Table 1
Crystallographic data and structure refinements data for [Ni(Salen)].DDH.
The Schiff base ligand, H2Salen, was prepared according to the
literature [17] by condensation between 1,2-etyhylenediamine
and 2-hydroxybenzaldehyde(2:1 mole ratio) in methanol and
recrystallized by dichloromethane/methanol mixed solvent through
the partial evaporation of dichloromethane. The [Ni(Salen)] complex
was prepared according to a method described previously [18].
The general procedure for the synthesis of the [Ni(Salen)].DDQ
adduct is as follows:
A dichloromethane solution containing an appropriate amount
of DDQ (0.227 g, 1.0 mmol) was added to a solution (20 mL) of
[Ni(Salen)] (0.325 g, 1.0 mmol) in dichloromethane. The color of
solution was changed to green immediately. n-Hexane was added
to the solution dropwise until the green precipitates were formed.
The precipitates were filtered and washed with n-hexane/dichloro-
methane. Suitable crystals were formed by the recrystallization of
precipitates in dichloromethane/chloroform. The needle crystals
were formed during a week.
[Ni(Salen)].DDQ.0.2CH2Cl2, Yield (80%). Anal. Calc. for C24.2H14.4
Cl2.4N4O4Ni: C, 51.08; H, 2.55; N, 9.85. Found: C, 51.07; H, 2.61; N,
9.98%. 1H NMR (CDCl3, dH)([Ni(Salen)].DDH): 3.45 (s, 4H, CH2CH2),
5.06 (S, 2H, phenolic OH), 6.53–6.84 (t, 2H, aromatic protons),
6.89–6.92 (d, 2H, aromatic protons), 7.01–7.06 (d, 2H, aromatic
protons), 7.11–7.26 (t, 2H, aromatic protons), and 7.53 (S, 1H,
HC@N).
Formula
C24H16Cl2N4NiO4
554.02
100(2)
Formula weight
Temperature (K)
Wavelength k (Å)
Crystal system
Space group
Crystal size (mm)
a (Å)
0.71073
triclinic
ꢀ
P1
0.21 Â 0.13 Â 0.09
8.5663 (7)
11.1559 (9)
13.9130 (11)
111.965 (1)
103.449 (2)
92.788 (2)
1185.63 (17)
1.552
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V
Dcalc (g cmÀ3
)
Z
2
h ranges for data collection
F(000)
1.64–30.1
564
Absorption coefficient
Index ranges
1.083
À12 6 h 6 12, À15 6 k 6 15,
À19 6 l 6 19
24736
Data collected
Unique data (Rint
)
6879, (0.037)
325/0
0.0421, 0.1220
0.0591, 0.1345
1.035
Parameters/restraints
a
Final R1, wR2 (Observed data)
a
Final R1, wR2 (All data)
Goodness of fit (GOF) on F2 (S)
Largest difference peak and hole
(e Å3)
1.77À0.35
a
R1
=
R
||Fo| À |Fc||/
R
|Fo|, wR2 = [
R
(w(F2o À F2c)2)/
R .
w(F2o)2]1/2
2.3. Crystal structure determination and refinement of
[Ni(Salen)].DDH
density, most probably, the disordered dichloromethane solvent
molecule, was treated with the SQUEEZE routine in PLATON [23].
The yellow plate crystal of [Ni(Salen)].DDH complex with a
dimension of 0.21 Â 0.13 Â 0.09 mm was chosen and mounted on
a glass fiber and used for data collection. Cell constants and an ori-
entation matrix for data collection were obtained by least-squares
refinement of diffraction data from 6879 unique reflections. Data
were collected at a temperature of 100 K to a maximum 2h value
3. Results and discussion
3.1. IR characteristics
of 60.2° in a series of
the Stoe X-AREA software package. The numerical absorption
coefficient, , for Mo K
radiation was 0.710 mmÀ1
x
scans at 1° oscillations and integrated using
The IR spectra of [Ni(Salen)], DDQ, [Ni(Salen)].DDQ and [Ni(Sa-
len)].DDH compounds studied in this work have been listed in
Table 2.
l
a
.
A numerical absorption correction was applied using X-RED and
X-SHAPE [19] softwares. The data were corrected for Lorentz and
Polarization effects. The structures were solved by direct methods
[20] and subsequent difference Fourier maps and then refined on
F2 by a full-matrix least-squares procedure using anisotropic
displacement parameters [21]. All hydrogen atoms were located
in a difference Fourier map and then refined isotropically. Atomic
factors were from International tables for X-ray crystallography.
All refinements were performed using the X-STEP32 crystallo-
graphic software package [22]. A summary of the crystal data,
experimental details and refinement results can be seen in Table 1
for [Ni(Salen)].DDH compound. A region of disordered electron
The strong band of IR at about 1616 cmÀ1 was assigned to C@N
band characteristic of [Ni(Salen)] complex [24]. The ring skeletal
vibrations (C@C) of Schiff base coordinated to the nickel ion were
seen at 1451 and 1535 cmÀ1. Important DDQ stretching frequen-
cies containing nitrile (N„C) and carbonyl (C@O) groups appeared
in 2233 and 1674 cmÀ1
, respectively. Carbonyl stretching
frequency of [Ni(Salen)].DDQ appeared at about 1675 cmÀ1 while
the nitrile vibrational frequency was seen at 2230 cmÀ1 as a week
peak. In the crystalline product, [Ni(Salen)].DDH, the vibrational
frequency of the carbonyl group disappeared completely and the
nitrile stretching frequency was seen at 2230 cmÀ1 as a medium
peak.