The construction of a novel bromido-and azido-bridged dinuclear copper(II) complex derived from 4-chloro-2-[(2-hydroxyethylimino)methyl]phenol

Article abstract of DOI:10.1080/15533174.2012.753623

A novel bromido- and azido-bridged dinuclear copper(II) complex, [Cu ₂Br₂L₂]·[Cu₂Br(N ₃)L₂]·H₂O, where L is the deprotonated form of the Schiff base 4-chloro-2-[(2-hydroxyethylimino)methyl]phenol, has been prepared and structurally characterized by elemental analysis, IR spectra, and single crystal X-ray crystallography. Each Cu atom in the complex is coordinated by three donor atoms of Schiff base ligand and by two bridging atoms, forming a square pyramidal geometry. The bromide and azide ligands are preferred bridging groups for the construction of dinuclear copper complexes with Schiff bases. Copyright Taylor and Francis Group, LLC.

Full text of DOI:10.1080/15533174.2012.753623

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The Construction of a Novel Bromido- and Azido-
Bridged Dinuclear Copper(II) Complex Derived From 4-
Chloro-2-[(2-hydroxyethylimino)methyl]phenol
Shao-Song Qian a , Hai-Hua Li b , Xiao-Shan Cheng b , Zhong-Lu You b & Hai-Liang Zhu a
a School of Life Sciences , Shandong University of Technology , ZiBo , P. R. China
b Department of Chemistry and Chemical Engineering , Liaoning Normal University , Dalian ,
P. R. China
Accepted author version posted online: 03 Jan 2013.Published online: 13 Mar 2013.
To cite this article: Shao-Song Qian , Hai-Hua Li , Xiao-Shan Cheng , Zhong-Lu You & Hai-Liang Zhu (2013) The
Construction of a Novel Bromido- and Azido-Bridged Dinuclear Copper(II) Complex Derived From 4-Chloro-2-[(2-
hydroxyethylimino)methyl]phenol, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:6,
687-690, DOI: 10.1080/15533174.2012.753623
To link to this article: http://dx.doi.org/10.1080/15533174.2012.753623
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:687–690, 2013
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.753623
The Construction of a Novel Bromido- and Azido-Bridged
Dinuclear Copper(II) Complex Derived
From 4-Chloro-2-[(2-hydroxyethylimino)methyl]phenol
Shao-Song Qian,1 Hai-Hua Li,2 Xiao-Shan Cheng,2 Zhong-Lu You,2
and Hai-Liang Zhu1
1School of Life Sciences, Shandong University of Technology, ZiBo, P. R. China
2Department of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, P. R. China
Cl
A
novel bromido- and azido-bridged dinuclear cop-
N
per(II) complex, [Cu2Br2L2]·[Cu2Br(N3)L2]·H2O, where L is
the deprotonated form of the Schiff base 4-chloro-2-[(2-
hydroxyethylimino)methyl]phenol, has been prepared and struc-
turally characterized by elemental analysis, IR spectra, and single
crystal X-ray crystallography. Each Cu atom in the complex is
coordinated by three donor atoms of Schiff base ligand and by
two bridging atoms, forming a square pyramidal geometry. The
bromide and azide ligands are preferred bridging groups for the
construction of dinuclear copper complexes with Schiff bases.
OH
OH
SCH. 1. The Schiff base HL.
EXPERIMENTAL
General Methods and Materials
Starting materials, reagents and solvents with AR grade were
purchased from commercial suppliers and used without further
purification. Elemental analyses were performed on a Perkin-
Elmer 240C elemental analyzer (Nanjing University, China).
The IR spectra were recorded on a Jasco FT/IR-4000 spec-
trometer (Liaoning Normal University, China) as KBr pellets
in the 4000–200 cm−1 region. Single crystal structural X-ray
diffraction was carried out on a Bruker SMART 1000 CCD area
diffractometer (Shandong University of Technology, China).
Caution: Sodium azide is potentially explosive, only small
quantity should be used and handled with great care.
Keywords copper complex, crystal structure, dinuclear complex,
Schiff base
INTRODUCTION
Dinuclear complexes with bridging groups are currently at-
tracting much attention for their interesting structures and wide
applications.[1–3] The Schiff bases derived from salicylaldehyde
and its derivatives are a kind of versatile ligands in coordi-
nation chemistry. The rational design and construction of din-
uclear complexes with Schiff bases are of particular interest
in coordination and structural chemistry. As is well known, Synthesis of the Schiff Base
the halide and pseudohalide groups can link two or more
metal atoms, yielding various polynuclear complexes.[4–9] To
our knowledge, there are no bromido-bridged dinuclear cop-
per complexes with Schiff bases derived from salicylaldehyde
and its derivatives have been reported so far. In this study, a
novel dinuclear Schiff base copper(II) complex with bromide
and azide bridges, [Cu2Br2L2]·[Cu2Br(N3)L2]·H2O, where L
is the deprotonated form of the Schiff base 4-chloro-2-[(2-
hydroxyethylimino)methyl]phenol (HL; Scheme 1), was suc-
cessfully prepared and characterized.
To the methanolic solution (30 mL) of the 5-chlorosalicy
laldehyde (1.0 mmol, 0.16 g) was added a methanolic solution
(20 mL) of 2-aminoethanol (1.0 mmol, 0.06 g) with stirring.
The mixture was stirred for 30 min at room temperature to
give yellow solution. The solvent was evaporated to give yellow
powder, which was washed with cold methanol and dried in air.
Yield 83%. Characteristic IR data: 1637 cm−1. Anal. Calcd. for
C9H10ClNO2 (%): C, 54.2; H, 5.0; N, 7.0. Found (%): C, 54.0;
H, 5.1; N, 7.1.
Synthesis of the Complex
To the methanolic solution (5 mL) of HL (0.1 mmol, 0.020 g)
was added a methanolic solution (5 mL) of CuBr2 (0.1 mmol,
0.022 g) and an aqueous solution (1 mL) of NaN3 (0.1 mmol,
0.006 g) with stirring. The mixture was stirred for 10 min at
room temperature, and then transferred to a stainless steel bomb,
Received 12 June 2012; accepted 21 November 2012.
Address correspondence to Hai-Liang Zhu, School of Life Sciences,
Shandong University of Technology, ZiBo 255049, P. R. China. E-mail:
hailiang zhu@163.com
687

688
S.-S. QIAN ET AL.
TABLE 1
Crystal data for the complex
TABLE 2
Selected bond lengths (Å) and angles (◦)
Formula
Mr
T (K)
Crystal shape/color
Crystal size (mm3)
Crystal system
Space group
a (Å)
C36H38Br3Cl4Cu4N7O9 Cu(1)-O(1)
1.914(7) Cu(1)-O(2)
1.938(9) Cu(1)-N(5)
2.000(7)
2.003(8)
1.898(7)
1.918(8)
2.801(2)
2.012(7)
2.905(2)
1.959(9)
2.005(7)
1348.4
Cu(1)-N(1)
298(2)
Cu(1)-Br(1)
2.766(2) Cu(2)-O(3)
2.015(6) Cu(2)-N(2)
2.005(8) Cu(2)-Br(1)
1.905(7) Cu(3)-O(6)
1.933(9) Cu(3)-Br(2)
2.432(2) Cu(4)-N(4)
1.910(7) Cu(4)-O(8)
2.384(2)
92.7(4) O(1)-Cu(1)-O(2)
83.0(4) O(1)-Cu(1)-N(5)
168.0(4) O(2)-Cu(1)-N(5)
93.4(2) N(1)-Cu(1)-Br(1)
94.9(2) N(5)-Cu(1)-Br(1)
95.0(3) O(3)-Cu(2)-N(5)
167.1(3) O(3)-Cu(2)-O(4)
81.8(3) N(5)-Cu(2)-O(4)
Block/blue
0.30 × 0.27 × 0.27
Monoclinic
P21/n
Cu(2)-O(4)
Cu(2)-N(5)
Cu(3)-O(5)
Cu(3)-N(3)
Cu(3)-Br3
Cu(4)-O(7)
Cu(4)-Br(2)
17.267(3)
13.119(3)
20.549(3)
91.746(2)
4652.7(15)
4
1.925
4.668
2656
9933
b (Å)
c (Å)
β (◦)
O(1)-Cu(1)-N(1)
N(1)-Cu(1)-O(2)
N(1)-Cu(1)-N(5)
O(1)-Cu(1)-Br(1)
O(2)-Cu(1)-Br(1)
O(3)-Cu(2)-N(2)
N(2)-Cu(2)-N(5)
N(2)-Cu(2)-O(4)
171.3(3)
90.0(3)
92.8(3)
102.1(3)
89.4(2)
94.0(3)
169.2(3)
87.7(3)
99.1(2)
90.6(2)
173.0(3)
90.1(2)
93.1(2)
91.1(3)
97.8(1)
173.0(3)
92.8(2)
93.2(2)
V (Å3)
Z
Dc (g cm−3
)
μ (Mo-Kα) (mm−1
F(000)
)
Independent reflections
Observed reflections (I ≥ 2σ(I))
Min. and max. transmission
Parameters
4177
O(3)-Cu(2)-Br(1) 100.1(2) N(2)-Cu(2)-Br(1)
0.335 and 0.365
574
9
0.964
0.0695, 0.1692
0.1879, 0.2339
N(5)-Cu(2)-Br(1)
O(5)-Cu(3)-N(3)
N(3)-Cu(3)-O(6)
88.4(2) O(4)-Cu(2)-Br(1)
93.7(3) O(5)-Cu(3)-O(6)
82.1(3) O(5)-Cu(3)-Br(3)
Restraints
Goodness-of-fit on F2
R1, wR2 [I ≥ 2σ(I)]a
R1, wR2 (all data)a
ꢀ
N(3)-Cu(3)-Br(3) 169.9(3) O(6)-Cu(3)-Br(3)
O(5)-Cu(3)-Br(2)
O(6)-Cu(3)-Br(2)
O(7)-Cu(4)-N(4)
N(4)-Cu(4)-O(8)
96.9(2) N(3)-Cu(3)-Br(2)
88.8(2) Br(3)-Cu(3)-Br(2)
94.3(3) O(7)-Cu(4)-O(8)
81.6(3) O(7)-Cu(4)-Br(2)
ꢀ
aR1 = Fo – Fc/Fo, wR2 = [ w(Fo2 – Fc2)/ w(Fo ) ]
.
2 2 1/2
N(4)-Cu(4)-Br(2) 156.0(3) O(8)-Cu(4)-Br(2)
which was sealed, heated at 150◦C for 12 h, and cooled gradually
to room temperature. Blue block-shaped crystals of the complex,
suitable for X-ray crystal structural determination, were formed
at the bottom of the bomb. The crystals were isolated by filtra-
tion, washed three times with methanol, and dried in air. Yield
35%. Characteristic IR data (cm−1): 2089 (s), 1645 (s), 1178
(m). Anal. Calcd. for C36H38Br3Cl4Cu4N7O9 (%): C, 32.1; H,
2.8; N, 7.3. Found (%): C, 30.9; H, 3.0; N, 7.1.
in Table 1. Selected bond lengths and angles are given in
Table 2.
RESULTS AND DISCUSSION
Chemistry
X-Ray Crystallography
The Schiff base HL was synthesized by the reaction
of equimolar quantities of 5-chlorosalicylaldehyde with 2-
aminoethanol in methanol. The air-stable yellow product of the
Schiff base is soluble in DMSO, DMF, methanol, ethanol, ace-
tonitrile, and chloroform, and insoluble in water. The elemental
analyses are in good agreement with the chemical formula pro-
posed for the compound. The complex was synthesized by the
reaction of the Schiff base with CuBr2 and sodium azide in
methanol at solvothermal condition.
Diffraction intensities for the complex were collected at
298(2) K using a Bruker SMART 1000 CCD area-detector
diffractometer (Shandong University Technology, China) with
MoKα radiation (λ = 0.71073 Å). The collected data were re-
duced with the SAINT program,[10] and multiscan absorption
correction was performed using the SADABS program.[11] The
structure was solved by direct methods, and refined against F2
by full-matrix least-squares method using the SHELXTL pack-
age.[12] All of the non-hydrogen atoms were refined anisotrop-
ically. The water H atoms in the complex were located from
a difference Fourier map and refined isotropically, with O–H
Structure Description of the Complex
The molecular structure of the complex is shown in Figure 1.
and H···H distances restrained to 0.85(1) and 1.37(2) Å, respec- The asymmetric unit of the complex contains a doubly
tively. The remaining hydrogen atoms were placed in calcu- bromido-bridged dinuclear copper(II) complex molecule,
lated positions and constrained to ride on their parent atoms. a mixed bromido and azido-bridged dinuclear copper(II)
The crystallographic data for the complexes are summarized complex molecule, and a water molecule of crystallization. The

BROMIDO- AND AZIDO-BRIDGED DINUCLEAR COPPER(II) COMPLEX
689
FIG. 1. A perspective view of the molecular structure of the complex with the
atom labeling scheme. The thermal ellipsoids are drawn at the 30% probability
level.
intramolecular Cu···Cu distances in the complex are 3.245(1)
and 3.406(1) Å. The Schiff bases behave as monoanionic and
tridentate ligands, which coordinate to the Cu atoms through
the three NNO donor atoms. Each Cu atom in the complex
is five-coordinated in a square pyramidal geometry, with the
FIG. 2. The molecular packing structure of the complex. Hydrogen bonds are
drawn as dashed lines.
The coordination number 5 for copper(II) complexes is very
basal plane defined by the NNO donor atoms of the Schiff common. The question arises as to whether the coordination
base ligand, and by one Br or N atom, and with the apical polyhedra around the Cu atoms can be described as distorted
position occupied by another Br or N atom. The average trans square pyramid or trigonal bipyramid. Further information can
angles are 169.6(2)◦ for Cu1, 168.2(2)◦ for Cu2, 171.4(2)◦ for be obtained by determining the structural index τ[18] that rep-
Cu3, and 164.5(2)◦ for Cu4. The Cu atoms deviate from the resents the relative amount of trigonality (square pyramid, τ =
least-squares planes defined by the four basal donor atoms by 0; trigonal bipyramid, τ = 1); τ = (β – α)/60◦, α and β being
0.167(1) Å for Cu1, 0.160(1) Å for Cu2, 0.137(1) Å for Cu3, the two largest angles around the metal atom. For the present
and 0.174(1) Å for Cu4, toward the apical donor atoms. In the complex, the values of τ are 0.06 (Cu1), 0.04 (Cu2), 0.05 (Cu3),
two molecules, the coordinate bond lengths related to the Cu and 0.28 (Cu4), indicating that all the Cu atoms in the complex
atoms are comparable to each other and also comparable to the adopt distorted square pyramidal coordination.
corresponding values observed in other similar halido-bridged
In the crystal structure of the complex, the copper com-
plex molecules and the water molecules are linked together by
copper(II) complexes with Schiff bases.[4,13–17]
TABLE 3
Hydrogen bond distances (Å) and bond angles (◦) for the complex
D–H···A
d(D–H)
d(H···A)
d(D···A)
Angle (D–H···A)
O(9)–H(9D)···O(3)i
O(9)–H(9C)···Br(3)ii
O(9)–H(9C)···O(5)ii
O(8)–H(8C)···O(9)iii
O(6)–H(6A)···O(7)
O(2)–H(2A)···O(9)iv
0.85(1)
0.85(1)
0.85(1)
0.93
0.93
0.93
1.94(2)
3.00(8)
1.94(2)
2.24
2.15
2.04
2.790(10)
3.428(7)
2.782(9)
2.781(11)
2.643(10)
2.651(11)
174(11)
113(7)
172(10)
116
112
122
Symmetry codes: i) x, y, 1 + z; ii): –1/2 + x, 1/2 – y, 1/2 + z; iii): 1/2 + x, 1/2 – y, –1/2 + z; iv) x, y, –1 + z.

690
S.-S. QIAN ET AL.
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IR Spectra
In the IR spectra of the complexes, the middle and broad
band centered at 3354 cm−1 is attributed to the vibration of
the water molecules. The strong absorption band at 1645 cm−1
can be assigned to the azomethine stretching frequencies of
the Schiff base ligand, whereas for the free Schiff base the
corresponding band was observed at 1637 cm−1. The shift of
these bands toward lower frequencies on complexation suggests
coordination to the Cu atoms through the imine N atoms.
The ν(C–O) mode is present as middle band at 1178 cm−1
.
The intense band at 2089 cm−1 is assigned to the stretching
vibration of the azide ligand. The weak bands indicative of
the Cu–O, Cu–N, and Cu–Br bonds are located in the region
600–300 cm−1
.
CONCLUSION
The present article reports the synthesis and crystal structure
of a novel bromido- and azido-bridged dinuclear copper(II)
complex with the tridentate Schiff base 4-chloro-2-[(2-
hydroxyethylimino)methyl]phenol. The bromide and azide
ligands are preferred bridging groups for the construction of
dinuclear copper(II) complexes with Schiff bases. The complex
may serve as interesting magnetic material, which deserve
further study.
12. Sheldrick, G. M. SHELXTL V5.1 Software Reference Manual; Bruker AXS,
Inc., Madison, WI, 1997.
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P. Chlorido-bridged polymeric and dinuclear copper(II) complexes with
tridentate Schiff base: Synthesis, crystal structure and magnetic properties.
Crystallogr. Rep. 2008, 53, 619–625.
SUPPLEMENTARY MATERIALS
CCDC 843682 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge 15. Zhang, N.; You, Z.-L. Syntheses and crystal structures of two tetranuclear
copper(II) complexes with Schiff bases. Transition Met. Chem. 2010, 35,
437–440.
16. Nayak, S.; Gamez, P.; Kozlevcar, B.; Pevec, A.; Roubeau, O.; Dehnen, S.;
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from
the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223–336-033; or e-mail:
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deposit@ccdc.cam.ac.uk.
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