Synthesis and structural characterization of a dinuclear cadmiumS1070328410121085 complex derived from 2-[(2-dimethylaminoethylimino) methyl]-6-ethoxyphenol

Article abstract of DOI:10.1134/S1070328410121085

Self-assembly among the Schiff base 2-[(2-dimethylaminoethylimino)methyl]- 6-ethoxyphenol (HL) with ammonium thiocyanate and cadmium(II) acetate affords a dinuclear cadmium(II) complex [Cd₂L₂(NCS)₂]. The complex was struct

Full text of DOI:10.1134/S1070328410121085

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2011, Vol. 37, No. 2, pp. 107–110. © Pleiades Publishing, Ltd., 2011.
Synthesis and Structural Characterization of a Dinuclear
Cadmium(II) Complex Derived from 2ꢀ[(2ꢀ
Dimethylaminoethylimino)methyl]ꢀ6ꢀethoxyphenol1
J. F. Lu*, S. T. Min, and H. G. Ge
School of Chemistry and Environmental Science, Shaanxi University of Technology, Hanzhong 723000, P.R. China
*eꢀmail: jiufulu@163.com
Received April 28, 2010
Abstract—Selfꢀassembly among the Schiff base 2ꢀ[(2ꢀdimethylaminoethylimino)methyl]ꢀ6ꢀethoxyphenol (HL)
with ammonium thiocyanate and cadmium(II) acetate affords a dinuclear cadmium(II) complex [Cd2L2(NCS)2].
The complex was structurally characterized by elemental analysis, IR spectrum, and singleꢀcrystal Xꢀray diffracꢀ
tion. The crystal structure of the complex was investigated. Both Cd atoms are best described as distorted pentagꢀ
onal bipyramids. The crystal of the complex is triclinic: space group P1,
a
= 11.3719(2), b = 11.7972(3), c =
= 2.
15.0847(3) α = 70.1520(10) β = 83.4690(10) γ = 62.2470(10) V , Z
Å,
°,
°,
°,
= 1682.13(6) Å3
DOI: 10.1134/S107032841101009X
1
INTRODUCTION
Synthesis of the Schiff Base (HL)
3ꢀEthoxysalicylaldehyde (1.0 mmol, 0.166 g) and
N,Nꢀdimethylethaneꢀ1,2ꢀdiamine (1.0 mmol,
Schiff bases have been widely used as chelating
ligands in coordination chemistry. A large number of
metal complexes derived from Schiff bases have been
investigated both for their versatile structures and
interesting applications [1–5]. The thiocyanate anion
readily coordinates to the metal atoms either through
the terminal mode or through the bridging mode,
yielding novel structures [6–8]. 2ꢀ[(2ꢀDimethylamiꢀ
noethylimino)methyl]ꢀ6ꢀethoxyphenol (HL) is a typꢀ
ical and simple Schiff base compound bearing four
donor atoms; however, the metal complexes with HL
have never been reported so far. In the present work, a
new dinuclear cadmium(II) complex [Cd2L2(NCS)2]
0.088 g) were mixed and stirred in a methanol solution
(25 ml). The mixture was refluxed for 30 min, and the
methanol was evaporated to give a yellow oil of HL.
The product was used for the synthesis of the complex
without purification.
Synthesis of Complex
I
To the stirred methanol solution (20 ml) of HL
(1.0 mmol, 0.236 g) and ammonium thiocyanate
(1.0 mmol, 0.076 g) was added a methanol solution
(10 ml) of cadmium acetate (1.0 mmol, 0.266 g). The
mixture was stirred at room temperature for 2 h to give a
colorless solution. Colorless blockꢀshaped crystals of the
complex were formed by the slow evaporation of the soꢀ
lution in air. The crystals were isolated by filtration,
washed with water and methanol, and dried in air. The
yield was 0.320 g (79%).
(I) was synthesized and characterized by elemental
analysis, IR spectrum, and singleꢀcrystal Xꢀray difꢀ
fraction.
EXPERIMENTAL
Materials and Instruments
For C28H38N6O4S2Cd2
anal. calcd., %: C, 41.4;
Found, %: C, 41.7;
H, 4.7;
H, 4.8;
N, 10.4.
N, 10.2.
The chemicals with AR grade were used as purꢀ
chased from Aldrich without further purification. C,
H, and N elemental analyses were performed with a
PerkinElmer elemental analyzer. The IR spectrum was
recorded on a Nicolet 520 FTꢀIR spectrophotometer
with a KBr pellet.
Xꢀray structure determination. Diffraction intensiꢀ
ties for the complex were collected at 298(2) K using a
Bruker SMART APEX II area detector with Mo
K
α
radiation (
λ
= 0.71073 Å). The collected data were
1
The article is published in the original.
reduced using the SAINT program [9], and multiscan
107

108
LU et al.
Table 1. Crystallographic data and experimental details for
complex
absorption corrections were applied using the
SADABS program [10]. The structure was solved by a
direct method and refined against F2 by the fullꢀmatrix
leastꢀsquares method using the SHELXTL package
[11]. All of the nonꢀhydrogen atoms were refined
anisotropically. Hydrogen atoms were placed in calcuꢀ
lated positions and constrained to ride on their parent
atoms. The crystallographic data for the complex I are
summarized in Table 1. Selected bond lengths and
angles are given in Table 2.
I
Parameter
Value
Formula weight
Space group
811.6
Triclinic
Atomic coordinates and other structural parameꢀ
ters of the complex have been deposited with the Camꢀ
bridge Crystallographic Data Centre (no. 770098;
deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.
ac.uk).
Unit cell dimensions
P1
11.3719(2)
11.7972(3)
15.0847(3)
70.1520(10)
83.4690(10)
62.2470(10)
1682.13(6)
2
a
, Å
, Å
b
RESULTS AND DISCUSSION
c
, Å
, deg
, deg
The cadmium ion and the Schiff base are used in a
1 : 1 molar ratio, so that the thiocyanate anions can
coordinate to the cadmium center. The complex is airꢀ
stable and moistureꢀinsensitive, and soluble in comꢀ
mon polar organic solvents such as methanol, ethanol,
acetonitrile, dimethylformamide, and dimethylsulꢀ
foxide, but insoluble in water.
α
β
γ, deg
The molecular structure of the complex
in the figure. Singleꢀcrystal Xꢀray diffraction study
indicates that complexes contain a phenolate oxygen
I is shown
3
V
Z
ρ
, Å
I
bridged dinuclear cadmium(II) complex. The Schiff
base ligand coordinates to the Cd atoms through all
the donor atoms. The thiocyanate ligands adopt a terꢀ
minal coordination mode.
, g cm–3
1.602
calcd
The dimeric bridging unit Cd2O2 describes a rhomꢀ
bohedral plane. The rhombohedral angles are
μ
, mm–1
1.429
O(1)Cd(1)O(3),
107.35(13)
Cd(1)O(3)Cd(2) 109.13(13)
70.49(11)
O(1)Cd(2)O(3)
. The Cd···Cd distance is
°
;
Cd(1)O(1)Cd(2)
°
;
72.82(11)
°
;
F(000)
816
°
3.632(2) Å. The coordination polyhedron around each
cadmium center is best described as a distorted penꢀ
tagonal bipyramid. The Cd(1) atom is coordinated by
two phenolate oxygens, two imine nitrogens, and two
amine nitrogen atoms from two Schiff base ligands.
The Cd(2) atom is coordinated by two phenolate oxyꢀ
gen and two ether oxygen atoms from two Schiff base
ligands and by two nitrogen atoms from two thiocyanꢀ
ate ligands. It is notable that the bond lengths of
Cd(2)–O(2) and Cd(2)–O(4) are much longer than
those of the Cd(2)–O(1) and Cd(2)–O(3) bonds,
which are caused by the geometrical need of the molꢀ
ecule, and the phenomenon has been observed in
many similar complexes [12–14]. Even though, the
coordinate bond lengths are consistent with the correꢀ
sponding values of analogous cadmium(II) complexes
with Schiff bases [15–17].
θ
range, deg
1.44–26.99
9990
Reflections measured
Independent reflections
Observed reflections
Variables
7001
5969
385
Restraints
6
R1
(
I
≥
2
σ
(
I
))
))
0.0441
0.0980
0.0524
0.1039
wR2
(
I
≥
2σ
(
I
The weak and broad band centered at 3445 cm–1 is
assigned to the cohesive water molecule. The intense
absorption band at 2058 cm–1 is assigned to the
stretching vibration of the terminal coordinated thioꢀ
cyanate groups. The strong absorption band at
R
1 (all data)
wR2 (all data)
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 2
2011

SYNTHESIS AND STRUCTURAL CHARACTERIZATION
109
Table 2. Selected bond lengths (Å) and bond angles (deg) for the complex
Bond
d
, Å
Bond
d, Å
Cd(1)–O(1)
Cd(1)–N(1)
Cd(1)–N(3)
Cd(2)–O(1)
Cd(2)–N(5)
2.286(3)
2.309(4)
2.321(4)
2.221(3)
2.176(5)
Cd(1)–O(3)
Cd(1)–N(2)
Cd(1)–N(4)
Cd(2)–O(3)
Cd(2)–N(6)
2.259(3)
2.416(4)
2.431(4)
2.198(3)
2.175(5)
Angle
ω
, deg
Angle
ω
, deg
O(3)Cd(1)O(1)
O(1)Cd(1)N(1)
O(1)Cd(1)N(3)
O(3)Cd(1)N(2)
N(1)Cd(1)N(2)
O(3)Cd(1)N(4)
N(1)Cd(1)N(4)
N(2)Cd(1)N(4)
N(6)Cd(2)O(3)
N(6)Cd(2)O(1)
O(3)Cd(2)O(1)
70.49(11)
76.72(13)
125.92(14)
99.89(13)
74.37(14)
134.57(14)
92.22(15)
115.00(15)
101.84(18)
125.7(2)
O(3)Cd(1)N(1)
O(3)Cd(1)N(3)
N(1)Cd(1)N(3)
O(1)Cd(1)N(2)
N(3)Cd(1)N(2)
O(1)Cd(1)N(4)
N(3)Cd(1)N(4)
N(6)Cd(2)N(5)
N(5)Cd(2)O(3)
N(5)Cd(2)O(1)
125.99(14)
76.50(13)
154.86(15)
134.46(14)
92.00(15)
100.44(15)
74.22(14)
111.8(2)
133.12(19)
109.03(18)
72.82(11)
C(23)
C(24)
N(4)
C(6)
C(22)
C(7)
C(10)
C(8)
C(9)
N(2)
C(1)
N(1)
C(21)
C(5)
N(3)
C(4)
Cd(1)
C(2)
C(3)
O(1)
C(11)
C(20)
C(12)
O(3)
O(2)
N(5)
C(15)
C(14)
C(26)
C(13)
S(1)
Cd(2)
C(19)
N(6)
C(27)
C(16)
O(4)
C(25)
C(28)
C(18)
C(17)
S(2)
Molecular structure of the complex, showing 30% probability thermal ellipsoids. Hydrogen atoms are omitted for clarity.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37 No. 2 2011

110
LU et al.
1625 cm–1 is assigned to the stretching vibration of the
azomethine groups ( (C=N)).
8. Brooker, S., Plieger, P.G., Moubaraki, B., et al., Angew.
Chem. Int. Ed., 1999, vol. 38, no. 3, p. 408.
ν
9. SMART & SAINT. Software Reference Manuals, Version
6.22, Bruker AXS Analytic XꢀRay Systems Inc., Madiꢀ
son (WI, USA), 2000.
ACKNOWLEDGMENTS
The authors thank the Scientific Research Founꢀ
dation of the Shaanxi University of Technology for
financial support (project no. SLGQD0708).
10. Sheldrick, G.M., SADABS, Software for Empirical
Absorption Correction, Göttingen (Germany): Univ. of
Göttingen, 2000.
11. Sheldrick, G.M., SHELXTL Reference Manual, Verꢀ
sion 5.1, Bruker AXS, Analytic XꢀRay Systems Inc.,
Madison (WI, USA), 1997.
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