Synthesis and crystal structure of a novel copper(II) complex derived from N,N'-Bis(3-ethoxysalicylidene)-1,2-ethanediamine

Article abstract of DOI:10.1080/15533174.2011.591299

A novel mononuclear copper(II) complex, [CuL]₂C₂ H₁₀N₂·2ClO₄ (H₂L = N,N'-bis(3-ethoxysalicylidene)-1,2-ethanediamine), has been synthesized and characterized by elemental analysis and singl

Full text of DOI:10.1080/15533174.2011.591299

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 41:750–753, 2011
Copyright ꢀ Taylor & Francis Group, LLC
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ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2011.591299
Synthesis and Crystal Structure of a Novel
Copper(II) Complex Derived from
N,Nꢀ-Bis(3-ethoxysalicylidene)-1,2-ethanediamine
Yong-Ming Cui,1 Peng Hou,2 and Zhong-Lu You2
1Engineering Research Center for Clean Production of Textile Printing, Ministry of Education, Wuhan
Textile University, Wuhan, P. R. China
2Department of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, P. R. China
A
novel mononuclear copper(II) complex, [CuL]2·C2
(H2L
N,Nꢀ-bis(3-ethoxysalicylidene)-1,2-
H10N2·2ClO4
=
ethanediamine), has been synthesized and characterized by
elemental analysis and single-crystal x-ray diffraction. The com-
pound consists of two mononuclear copper(II) complex molecules,
two perchlorate anions, and one protonated ethane-1,2-diamine
molecule that bridges adjacent two copper(II) complex molecules
through hydrogen bonds. The CuII atom is four-coordinate in a
square-planar geometry, with two imino N and two phenolic O
atoms of the Schiff base ligand.
Keywords copper(II), crystal structure, hydrogen bonds, Schiff base,
EXPERIMENTAL
synthesis
Materials and Measurements
Commercially available 3-ethoxysalicylaldehyde and
ethane-1,2-diamine were purchased from Aldrich and used
without further purification. Other solvents and reagents were
made in China and used as obtained. C, H, and N elemental
analyses were performed with a Perkin-Elmer elemental
analyzer.
Caution: Metal perchlorate salts are potentially explosive.
Only a small amount of material should be prepared and it
should be handled with care.
INTRODUCTION
Metal-organic complexes containing bridging ligands are of
current interest because of their interesting molecular structures
and widely applications.[1–3] Copper is one of the most im-
portant transition metal ions in biological systems; it plays an
important role in transport and activation of molecular oxy-
gen.[4,5] The bidentate ligand ethane-1,2-diamine is a good
bridging group and forms a great many polynuclear com-
plexes with silver(I) ions.[6–10] However, for the copper(II)
complexes, only one ethane-1,2-diamino-bridged polynuclear
structure was reported.[11] In this article, a novel mononu-
clear copper(II) complex [CuL]2·C2H10N2·2ClO4 (H2L = N,Nꢁ-
bis(3-ethoxysalicylidene)-1,2-ethanediamine; see the scheme)
has been synthesized and structurally characterized.
Synthesis of the Schiff Base H2L
3-Ethoxysalicylaldehyde (2.0 mmol, 332.4 mg) and ethane-
1,2-diamine (1.0 mmol, 60.1 mg) were dissolved in ethanol (30
mL) with stirring. The mixture was stirred for about 10 min
to give an amount of yellow precipitate. The precipitate was
filtered out, washed three times with cold ethanol, and dried in
a vacuum over anhydrous CaCl2. Yield: 87%. Anal.: Calcd. for
C20H24N2O4 (FW 356.4): C, 67.4; H, 6.8; N, 7.9%. Found: C,
67.2; H, 6.9; N, 7.7%.
Received 9 October 2010; accepted 17 February 2011.
This work was financed by the Education Office of Hubei Province
(Q20101610).
Address correspondence to Zhong-Lu You, Department of Chem-
istry and Chemical Engineering, Liaoning Normal University,
Huanghe Road 850, Shahekou District, Dalian, P. R. China. E-mail:
youzhonglu@yahoo.com.cn
Synthesis of [CuL]2·C2H10N2·2ClO4
An ethanol solution (5 mL) of Cu(ClO4)·6H2O (0.1 mmol,
37.0 mg) was added to an ethanol solution (10 mL) of H2L (0.1
mmol, 35.6 mg) and stirred at room temperature for 10 min.
Then an ethanol solution (5 mL) of ethane-1,2-diamine (0.1
750

SYNTHESIS AND STRUCTURE OF NOVEL COPPER(II) COMPLEX
751
TABLE 1
Crystallographic and experimental data for the complex
Formula
Mr
C42H54Cl2Cu2N6O16
1096.89
Block/blue
0.23 × 0.20 × 0.20
Monoclinic
P21/c
18.988(2)
13.785(2)
18.430(2)
Dc/g cm−3
1.563
1.104
2272
0.0407
26796
10079
6043
12/619
0.7853/0.8094
µ/mm−1 (MoKα)
F(000)
Crystal shape/color
Crystal size/mm3
Crystal system
Space group
a/Å
Rint
Measured reflections
Unique reflections
Observed reflections I ≥ 2σ(I)
Restraints/parameters
Minimum and maximum
transmission
b/Å
c/Å
β/◦
V/Å3
Z
104.890(2)
4661.9(8)
4
Goodness of fit on F2
R1, wR2 [I ≥ 2σ(I)]a
R1, wR2 (all data)a
Large diff. peak and hole/(e.Å−3
)
1.034
0.0534, 0.1375
0.0969, 0.1644
0.576/–0.572
T/K
ꢀ
298(2)
ꢀ
ꢀ
ꢀ
2
2 2
2 2 1/2
aR1 = ||Fo|-|Fc||/ |Fo|, wR2 = [ w(Fo -Fc ) / w(Fo ) ]
.
TABLE 2
mmol, 6.0 mg) was added dropwise with continuous stirring.
The mixture was stirred for another 10 min at room temperature
to give a blue solution. Suitable blue single crystals for the
structure determination were obtained by slow evaporation of
the resulting solution in air. Yield: 45% on the basis of H2L.
Anal.: Calcd. for C42H54Cl2Cu2N6O16 (FW 1096.9): C, 46.0;
H, 5.0; N, 7.7%. Found: C, 46.4; H, 5.2; N, 7.9%.
Selected bond lengths (Å) and angles (◦) for the complex
Cu1-O1
Cu1-N1
Cu2-O5
Cu2-N3
1.907(3)
1.945(3)
1.912(2)
1.936(3)
Cu1-O2
Cu1-N2
Cu2-O6
Cu2-N4
1.917(3)
1.943(3)
1.911(3)
1.945(3)
O1-Cu1-O2 90.6(2)
O2-Cu1-N2 93.2(2)
O2-Cu1-N1 174.5(2)
O6-Cu2-O5 90.2(2)
O5-Cu2-N3 93.0(2)
O5-Cu2-N4 177.0(2)
O1-Cu1-N2 176.2(2)
O1-Cu1-N1 92.8(2)
N2-Cu1-N1 83.6(2)
O6-Cu2-N3 173.6(2)
O6-Cu2-N4 92.4(2)
N3-Cu2-N4 84.5(2)
TABLE 3
Hydrogen-bond geometry (Å, ◦) for the complex
D−H···A
D−H
H···A
D···A
D−H···A
N5−H5A···O14#1 0.89
N5−H5A···O13#1 0.89
N5−H5A···Cl2#1 0.89
2.25
2.53
2.89
2.04
2.21
1.93
2.24
1.99
2.20
2.09
2.09
2.10
2.87
3.090(5)
3.294(7)
3.754(3)
2.868(4)
2.760(4)
2.721(4)
2.922(4)
2.762(4)
2.924(4)
2.716(4)
2.863(5)
2.978(5)
3.699(3)
157
144
165
155
120
147
134
145
138
127
144
169
156
N5−H5B···O8
N5−H5B···O6
N5−H5C···O5
N5−H5C···O7
N6−H6A···O2#2
N6−H6A···O4#2
N6−H6B···O1#2
N6−H6B···O3#2
0.89
0.89
0.89
0.89
0.89
0.89
0.89
0.89
N6−H6C···O10#3 0.89
N6−H6C···Cl1#3 0.89
FIG. 1. The ethane-1,2-diamine bridged dimeric of Cu1 moieties. Displace-
ment ellipsoids are drawn at the 30% probability level. Hydrogen bonds are
shown as dashed lines.
Symmetry codes: #1: 1 – x, 1 – y, 1 – z; #2: x, y, 1 + z; #3: – x, 1 –
y, 1 – z.

752
Y.-M. CUI ET AL.
DATA COLLECTION, STRUCTURAL DETERMINATION,
AND REFINEMENT
Crystal Structure Determination
Diffraction intensities for the complex were collected at
298(2) K using a Bruker Smart 1000 CCD area-detector with
MoKα radiation (λ = 0.71073 Å). The collected data was re-
duced using the SAINT program,[12] and multiscan absorption
correction was performed using the SADABS program.[13] The
structure was solved by direct method and refined against F2 by
a full-matrix least-squares method using the SHELXTL pack-
age.[14] All of the nonhydrogen atoms were refined anisotrop-
ically. H atoms were placed in calculated positions and con-
strained to ride on their parent atoms. The crystallographic data
for the complex are summarized in Table 1. Selected bond
lengths and angles are given in Table 2. Hydrogen bonds are
listed in Table 3. Crystallographic data for the complex has
been deposited with the Cambridge Crystallographic Data Cen-
tre (CCDC 692177).
RESULTS AND DISCUSSION
Preparation of H2L and the Complex
H2L was prepared according to the standard method with
high yield. This compound was known to coordinate with
FIG. 2. The ethane-1,2-diamine bridged dimeric of Cu2 moieties. Displace-
ment ellipsoids are drawn at the 30% probability level. Hydrogen bonds are
shown as dashed lines.
FIG. 3. Molecular packing arrangement of the complex. Hydrogen bonds are shown as dashed lines.

SYNTHESIS AND STRUCTURE OF NOVEL COPPER(II) COMPLEX
753
transition metal atoms through the imino N and phenolic O
atoms, [15–17] and to coordinate with rare earth metal atoms
through the phenolic O and ether O atoms.[18–20] Ethane-1,2-
diamine was added to the reaction aiming at obtaining a
polynuclear complex; however, it bridges the adjacent com-
plex molecules through the hydrogen bonds, instead of the
coordination bonds. The preparation of the complex is sum-
marized in the following equation:
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H2L + Cu(ClO4) · 6H2O + NH2CH2CH2NH2
→ [CuL]2 · C2H10N2.2ClO4.
Structure Description of the Complex
The asymmetric unit of the complex consists of two mononu-
clear CuL moieties, one protonated ethane-1,2-diamine cation,
and two perchlorate anions. Adjacent CuL moieties are bridged
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bonds, forming centrosymmetric dimers (Figures 1 and 2).
The perchlorate anions are linked to the ethane-1,2-diamine
molecules through N–H···O hydrogen bonds. In each of the
CuL moieties, the CuII atom is four-coordinated by two imino N
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and two phenolic O atoms of L, forming a square-planar geom-
etry. The Cu1 and Cu2 atoms are respectively 0.030(2) Å and
0.034(2) Å out of the corresponding planes defined by the four
donor atoms. The bond angles for the five-membered chelate
rings are in the range 83.6(2)–84.5(2)◦. The overall molecular
structures of the dimers and the coordinate bond parameters are
very similar. The Cu–N and Cu–O bond lengths are comparable
to those reported for Schiff base copper(II) complexes.[21–23]
In the crystal structure, adjacent molecules are linked through
intermolecular N−H···O hydrogen bonds, forming dimers (Fig-
ure 3). There are no short contacts among the dimers.
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CONCLUSIONS
The Schiff base ligand N,Nꢁ-bis(3-ethoxysalicylidene)-1,2-
ethanediamine coordinates to the Cu atom through the two imino
N and two phenolic O atoms. The ethane-1,2-diamine molecule
can bridge adjacent complex molecules tightly with hydrogen
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metal atoms, but they are very easily located at the lattice of the
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