Structure and characterization of bis(N-p-chloro-phenyl-salicylideneaminate) Schiff base copper(II) complex: Cu[N-p-Cl-Ph-Sal]2

Article abstract of DOI:10.1023/A:1014366326391

The crystal and molecular structure of the title compound has been determined by X-ray crystallography. It crystallizes in the monoclinic system, space group P2₁/c, with lattice parameters a = 13.678(3), b = 10.729(2), c = 8.1996(2) A, β= 98.96°, V = 1188.7(4) A ³, and Z = 4. The crystal structure contains two centrosymmetric molecules of bis (N-p-chloro-phenyl-salicylideneaminate) Schiff base copper(II). Copper(II) ion is coordinated in a slightly distorted trans square-planar configuration, the distortion consisting of a reduction of the N-Cu-O angle with the chelate rings from the ideal value of 90°. The p-chlorophenyl rings with salicylidene moieties form a dihedral angle of 38.96°.

Full text of DOI:10.1023/A:1014366326391

C
Journal of Chemical Crystallography, Vol. 31, No. 5, May 2001 ( 2002)
Structure and characterization
of bis(N-p-chloro-phenyl-salicylideneaminate)
Schiff base copper(II) complex: Cu[N-p-Cl-Ph-Sal]2
Qiaofeng Han,(1) Fangfang Jian,(1) Lude Lu,(1) Xujie Yang,(1) and Xin Wang(1)*
Received January 28, 2001
The crystal and molecular structure of the title compound has been determined by X-ray
crystallography. It crystallizes in the monoclinic system, space group P21/c, with lattice
˚
parameters a = 13.678(3), b = 10.729(2), c = 8.1996(2) A, = 98.96 , V = 1188.7(4)
3
˚
A , and Z = 4. The crystal structure contains two centrosymmetric molecules of bis
(N-p-chloro-phenyl-salicylideneaminate) Schiff base copper(II). Copper(II) ion is coor-
dinated in a slightly distorted trans square-planar configuration, the distortion consisting of
a reduction of the N Cu O angle with the chelate rings from the ideal value of 90 . The
p-chlorophenyl rings with salicylidene moieties form a dihedral angle of 38.96 .
KEY WORDS: Copper complex; salicylideneaminate; Schiff base; square-planar.
lene producing alkylchrysanthemate3 and as in-
hibitors in the oxidation of polyethylene glycols
in solution.4 In this paper, we report the synthesis
of the Schiff base of p-chloroaniline with salicy-
laldehyde and the crystal structure of its copper(II)
complex.
Introduction
There is considerable current interest in the
coordination chemistry of transition metals with
the Schiff base family of ligands.1,2 In most
cases, it was found that chelation of the bases
with salts of transition metals occurred readily,
whereas those Schiff bases which are prepared
from ortho-hydroxy substituted aldehydes readily
form chelates similar to the type obtained from
8-hydroxyquinoline and its derivatives. We se-
lected the salicylidene Schiff base as a ligand
because it could promote chelation and provide
extra stability to the metal centers. Copper(II)
complexes of N-substituted salicylideneaminates
Experimental
All chemicals were of analytical grade and
used directly without further purification.
Synthesis of Schiff base
N-p-chloro-phenyl-salicylideneaminate (1)
---- == ----
(C6H6(O ) CH N R) may be used as active
catalysts for cyclopropanation of tetramethylethy-
A solution of salicylaldehyde (1 mol) in an-
hydrous ethanol (100 mL) was added dropwise
to a solution of p-chloroaniline (1 mol) also
in 100 mL of anhydrous ethanol. The reaction
mixture was stirred for 1 h at room temperature,
(1) Materials Chemistry Laboratory, Nanjing University of Science
and Technology, Nanjing 210094, People’s Republic of China.
* To whom correspondence should be addressed; e-mail: wxin@
public1.ptt.js.cn.
247
C
1074-1542/01/0500-0247/0 2002 Plenum Publishing Corporation

248
Han, Jian, Lu, Yang, and Wang
IR and UV analysis
and yielded a yellow precipitate. After filtration,
the yellow product was recrystallized with ethanol
and a yellow crystal was obtained (yield 90%).
The IR spectrum (KBr pellets, Bruker Vector
----
22 spectrometer) showed phenolic C O stretch-
1
----
ing bands at 1326 and 1089 cm for C Cl,
Synthesis of bis(N-p-chloro-phenyl-
salicylideneaminate) Schiff base copper(II)
complex (2)
1
1
==
1607 cm for C N, and 1445–1535 cm for
==
C C of the phenyl ring respectively. The absence
of v(O H) at 3100 cm 1 in the IR spectra of the
----
copper(II) complex 2, suggests that the ligand 1
liberates one proton upon complexation, thus act-
ing as a negatively charged bidentate chelate. The
band at 416 cm 1 is assigned to the vCu N stretch-
To a solution of 0.58 g of the ligand (1)
(2.5 mmol) in EtOH (30 mL) was added with stir-
ring 0.25 g of (CH3COO)2Cu H2O (1.25 mmol) in
EtOH(20mL). Thereactionlasteduntiltheyellow
color completely disappeared and a brown-green
solid precipitated. After filtration, the product was
dissolved in CHCl3 and evaporated at room tem-
perature. Brown rhombohedral crystals were ob-
tained. The C, H, and N content was determined
by elemental analysis (Found: C, 59.29; H, 3.46;
N, 5.42%, C26H18Cl2CuN2O2 Calcd: C, 59.43; H,
3.42; N, 5.33%).
1
ing vibration, and the band at 526 cm can be
assigned to the vCu O stretching vibration mode.
The UV spectra of the title complex show
two bands with maxima at about 276 and 242 nm.
The bands are assigned to the
–
transition of
==
==
C N and C C bands.
Single crystal analysis
Table 1. Summary of Crystallographic Results for Cu[N-p-Cl-
A summary of the key crystallographic in-
formation is given in Table 1. A selected crystal
was mounted on a four-circle CAD4 diffrac-
tometer. Intensities were corrected for Lorentz
Ph-Sal]2
Color/shape
Empirical formula
CCDC No.
Formula weight
Crystal size, nm
Crystal system
Space group
Brown/rhombohedral
C13H13ClCuNO
CCDC-1003/6045
298.23
0.20 0.40 0.30
Monoclinic
P21/c
3
2 a
˚
Table 2. Anisotropic Displacement Parameters (10 A )
U11 U22 U33 U23 U13 U12
40(1) 222(1) 180(1) 5(1)
˚
Unit cell dimensions
a = 13.678(3) A
˚
b = 10.729(2) A
˚
Cl(1)
Cu(1)
O(1)
N(1)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
74(1) 21(1)
7(1) 2(1)
15(1) 12(1)
c = 8.1996(16) A
43(1)
56(1)
38(1)
53(2)
59(2)
46(1)
58(1)
39(1)
64(2)
96(2)
38(1)
45(1)
41(1)
54(2)
66(2)
85(3)
5(1)
19(1)
5(1)
12(2)
29(2)
3(2)
12(2)
2(2)
5(1)
3(1)
6(1)
1(2)
3(2)
9(2)
4(1)
2(1)
= 98.96(3)
1188.7(4)
4
3
˚
Cell volume, A
Z
3(1)
11(2)
11(2)
28(2)
1(1)
3(1)
4(2)
5(2)
Density (Calculated), mg/m3
Absorption coefficient, mm
F(000)
1.666
2.042
608
1
34(2) 135(3)
50(2)
38(2)
39(2)
48(2)
42(2)
61(2)
71(2)
49(2)
39(2)
44(2)
96(3) 120(3)
42(2) 14(2)
˚
Radiation
Temperature, K
range, deg
Mo K ( = 0.71073 A)
67(2)
55(2)
36(2)
38(1)
39(2)
46(2)
60(2)
55(2)
40(2)
91(2)
43(2)
38(1)
35(1)
40(2)
50(2)
57(2)
50(2)
38(1)
19(2)
3(1)
1(1)
3(1)
0(1)
5(2)
2(1)
5(1)
2(1)
5(1)
293(2)
1.51–27.44
Limiting indices
17
0
h
17, 13
10
k
13,
l
Independent observed
reflections
1580 [R = 0.0306]
int
4(2) 22(2)
10(2) 19(2)
R[I > 2 (I)]
R1 = 0.0658, wR2 = 0.1080
R1 = 0.1077, wR2 = 0.1198
1.152
1(1)
1(1)
2(1)
0(1)
R indices (all data)
Goodness of fit on F2
Largest diffraction peak
0.294 and 0.323
2
aThe anisotropic displacement factor exponent takes the form:
[h2 a2 U11
+ 2h ka bU12].
2
3
˚
and hole, e/A
+

Crystal structure of Cu[N-p-Cl-Ph-Sal]2
249
and polarization effects and empirical absorp-
tion, and the data reduction was done using
SADABS5 program. The structure was solved by
direct methods and refined by least squares on
F2 on all data by using the SHELXTL6 soft-
ware package. All non-H atoms were anisotropi-
cally refined. The hydrogen atoms were located
from the different map and refined isotropi-
cally. Corrections for Lp factors and absorption
were applied and the final cycle of full-matrix
least-squares refinement gave final R = 0.0658
and wR = 0.1080, w = 1/[ 2 Fo2 + (0.0546P)2],
where P = (Fo2 + 2Fc2)/3. The molecular graph-
ics were plotted using SHELXTL.6 Atomic scat-
tering factors and anomalous dispersion correc-
tions were taken from International Tables for
X-rayCrystallography.7 Theanisotropic displace-
ment parameters are given in Table 2.
Fig. 1. The molecular structure of Cu[N-p-Cl-Ph-Sal]2 with
the atomic numbering scheme.
amino N atoms. The six-membered chelate ring
is planar with the mean deviation from the best
plane of 0.213(1) A. The copper atom is located
Results and discussion
˚
Figure 1 shows the molecular structure. Se-
lected bond lengths (A) and bond angles (deg) are
in the center of the coordination plane defined by
O(1), N(1), C(7), C(8), C(13) and O(1A), N(1A),
C(7A), C(8A), C(13A). This plane is nearly par-
allel to that of salicylaldehyde ring, and the di-
hedral angle between them is only 10.07 . The
p-chlorophenyl rings with the salicylidene group
form a dihedral angle of 38.96 . The bond dis-
˚
presented in Table 3. The crystal structure con-
tains two centrosymmetric molecules of Cu[N-
p-Cl-Ph-Sal]2. The copper(II) ion is coordinated
in a slightly distorted trans square-planar config-
uration, the distortion consisting of a reduction
---- ----
----
----
of the N Cu O angle with the chelate rings
tances of Cu O(1) and Cu N(1) for Cu[N-p-
˚
from the ideal value of 90 . The coordination ge-
Cl-Ph-Sal]2 are 1.887(2) and 2.040(2) A respec-
ometry of copper(II) is square planar with two
tively. All these parameters are in close agreement
----
----
equivalent Cu N and Cu O bonds. The Schiff
base loses a proton from the hydroxyl group and
acts as a single charged bidentate ligand coordi-
nating to copper(II) through the hydroxyl O and
with those reported for square-planar copper(II)
10
compounds.8
----
The C C, C Cl, C O, and
----
----
----
C
N bond lengths of the title compound are in
the normal range.
˚
Table 3. Selected Bond Lengths (A) and Bond Angles (deg) of the Title Compound
Bond lengths
Cu(1) O(1)
N(1) C(6)
C(13) O(1)
1.887(2) Cu(1) N(1)
1.433(4) N(1) C(7)
1.325(3) C(3) Cl(1)
2.042(2)
1.303(3)
1.749(4)
Bond angles
O(1) Cu(1) O(1A)
O(1) Cu(1) N(1A)
C(4) C(3) Cl(1)
180.0
88.55(9)
119.5(3)
O(1) Cu(1) N(1)
C(6) N(1) Cu(1)
N(1) C(7) C(8)
91.45(9)
121.95(17)
127.7(2)

250
Han, Jian, Lu, Yang, and Wang
6. Sheldrick, G.M. SHELXTL V5, Reference Manual;
Siemens Analytical X-ray Sysytems, Inc.: Madison, WI,
1996.
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