84
S. Ray et al. / Polyhedron 33 (2012) 82–89
off, washed several times with cold methanol and dried in vacuo
over fused CaCl2.
isolated by filtration and air-dried. Yield: (0.395 g, 61% with re-
spect to zinc). Anal. Calc. for C26H30N22Zn2: C, 40.06; H, 3.59; N,
L1: Yield: 2.10 g (81%); mp (°C) 140. Anal. Calc. for C13H15N5: C,
64.73; H, 6.22; N, 29.04. Found: C, 64.55; H, 6.15; N, 28.82%; IR
39.53. Found: C, 40.01; H, 3.51; N, 39.10%; IR (KBr,
m
/cmꢀ1): 2054
(vs) ( as, N3), 1579 (s) ( C@Npym), 1630 (
m
m
m
C@N); 1H NMR (d6-DMSO,
(KBr,
m
/cmꢀ1): 3270 (m) (
m
N–H), 2980 (w), 2920 (w) (
m
C–H), 1360
d/ppm): 2.41 (3H, d, 3.9 Hz, 40-CH3), 2.55 (3H, d, 3.9 Hz, 60-CH3),
2.58 (3H, s, @C–CH3), 6.95 (1H, br s, H-50), 7.65 (1H, br s, NH),
7.74 (1H, m, H-5), 8.09 (1H, br s, H-3), 8.18 (1H, br s, H-4), 8.50
(1H, br s, H-6).
(s) (dCH ), 1215 (ms) (mC@C), 1065 (m) (pym), 1640 (mC@Npym),
1635 (m3C@NH); H NMR (d6-DMSO, d/ppm): 2.46 (6H, s, 40-CH3 and
60-CH3), 2.52 (3H, s, @C–CH3), 6.81 (1H, s, H-50), 7.46 (1H, t,
7.8 Hz, H-4), 7.94 (1H, br d, 8.1 Hz, H-3), 8.69 (1H, dd, 4.0, 0.8 Hz,
H-6), 10.23 (1H, br s, NH).
1
2.4.2. Preparation of complex 2
The ligand L2 was prepared following the same procedure as
that of L1, but using pyridine-2-carbaldehyde (2.40 g, 10 mmol)
in place of 2-acetyl pyridine.
L2: Yield: 3.13 g (85%); mp (°C) 152. Anal. Calc. for C12H13N5: C,
63.43; H, 5.72; N, 30.83 Found: C, 63.22; H, 5.61; N, 30.20%; IR
Complex 2 was prepared by the same procedure as 1 using
Cd(ClO4)2ꢂ6H2O as the metal precursor. Yield: (0.548 g, 65.5%).
Anal. Calc. for C26H30N22Cd2: C, 35.64; H, 3.42; N, 35.20. Found:
C, 35.45; H, 3.39; N, 35.00%. IR (KBr,
m
/cmꢀ1): 2058 (vs) (
m
as, N3),
1575 (s) ( C@Npym), 1625 (
m
m
C@N); 1H NMR (d6-DMSO, d/ppm): 2.39
(KBr,
1570 (
m
m
/cmꢀ1): 3265 (m) (
C@NPy), 1640 (
m
N–H), 2975 (
mC–H), 1590 (mbr) (pym),
(3H, s, 40-CH3), 2.46 (3H, s, 60-CH3), 2.50 (3H, s, @C–CH3), 6.92
(1H, br s, H-50), 7.66 (2H, br s, H-5 and NH), 8.05 (1H, br s, H-3),
8.15 (1H, br s, H-4), 8.53 (1H, br s, H-6).
m
C@Npym), 1630 (
m
C@NH); 1H NMR (d6-DMSO,
d/ppm): 2.46 (6H, s, 40-CH3 and 60-CH3), 6.79 (1H, s, H-50), 7.46
(1H, dd, 7.8, 4.5 Hz, H-5), 7.96 (1H, t, 7.8 Hz, H-4), 8.13 (1H, br d,
8.1 Hz, H-3), 8.3 (1H, s, @C–H), 8.69 (1H, dd, 4.5 Hz, H-6), 11.54
(1H, br s, NH).
2.4.3. Preparation of complex 3
To a methanol solution (30 ml) of Cd(ClO4)2ꢂ6H2O (0.838 g,
2 mmol), a solution of the Schiff base L2 in the same solvent
(0.454 g, 2 mmol) was slowly added with stirring at room temper-
ature, followed by drop by drop addition of a 2 ml aqueous solution
of KSCN (0.388 g, 4 mmol). The stirring was continued for an addi-
tional 2 h and the solution was then filtered. The pale yellow solu-
tion was kept at room temperature, which produced yellow
hexagonal crystals suitable for X-ray diffraction after a week. The
crystals were isolated by filtration and air-dried. Yield: (0.556 g,
61.5%). Anal. Calc. for C28H26N14S4Cd2: C, 36.85; H, 2.85; N, 21.51.
2.4. Preparation of the complexes
2.4.1. Preparation of complex 1
To a methanol solution (30 ml) of Zn(ClO4)2ꢂ6H2O (0.744 g,
2 mmol), a solution of the Schiff base L1 in the same solvent
(0.482 g, 2 mmol) was slowly added, followed by a solution of so-
dium azide (0.260 g, 4 mmol) in a minimum volume of aqueous
methanol with constant stirring. The stirring was continued for
additional 2 h and filtered. The light yellow solution was kept at
room temperature, which produced yellow hexagonal crystals
suitable for X-ray diffraction after 10 days. The crystals were
Found: C, 36.67; H, 2.80; N, 21.30%. IR (KBr,
and 2098 (vs) ( as, NCS), 1578 (s) ( C@Npym), 1610 (
(d6-DMSO, d/ppm): 2.42 (3H, s, 40-CH3), 2.46 (s, 60-CH3), 6.94 (1H,
m
/cmꢀ1): 2098 (vs)
C@N); 1H NMR
m
m
m
Table 1
Experimental data for crystallographic analysis of 1, 2 and 3.
Complex
1
2
3
Empirical formula
Formula weight
T (K)
C
26H30N22Zn2
C26H30Cd2N22
875.54
100
C28H26Cd2N14S4
911.73
293
779.48
150
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
0.71073
monoclinic
C2/c
0.71073
monoclinic
C2/c
0.71073
triclinic
P1
ꢀ
16.670(4)
14.544(3)
14.556(3)
90
107.552(8)
90
3364.8(13)
4
1.539
16.927(4)
14.844(4)
14.249(4)
90
104.876(3)
90
3460.3(16)
4
1.681
1.284
9.311(5)
13.761(5)
16.253(5)
109.271(5)
92.116(5)
104.893(5)
1882.8(14)
2
1.608
1.392
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (mg mꢀ3
)
Absorption coefficient (mmꢀ1
F(000)
)
1.485
1592
1744
904
h range (°) for data collection
Index ranges
1.9–25.6
1.9–27.9
1.3–28.1
ꢀ20 6 h 6 20
ꢀ17 6 k 6 17
ꢀ17 6 l 6 17
2.021
ꢀ21 6 h 6 22
ꢀ19 6 k 6 18
ꢀ11 6 l 6 18
1.067
ꢀ12 6 h 6 11
ꢀ18 6 k 6 18
ꢀ19 6 l 6 19
1.033
Goodness-of-fit (GOF) on F2
Completeness to h = 25.00° (%)
98.7
97.2
93.8
Independent reflections [Rint
Absorption correction
Refinement method
Data/restraints/parameters
Reflections collected
]
3162 [Rint = 0.204]
multi-scan
full-matrix least squares on F2
3162/0/229
15358
3712 [Rint = 0.030]
multi-scan
full-matrix least squares on F2
3712/0/233
12588
8597 [Rint = 0.034]
multi-scan
full-matrix least squares on F2
8597/442/0
24938
Final R indices [I > 2
r(I)]
R1 = 0.0442 wR2 = 0.2240
0.87, ꢀ1.03
0.832 and 0.793
R1 = 0.0366 wR2 = 0.0793
0.950, ꢀ0.481
0.9042 and 0.7833
R1 = 0.0439 wR2 = 0.1225
ꢀ0.89, 1.03
0.8632 and 0.8446
Largest difference peak and hole (eÅꢀ3
Maximum and minimum transmission
)