The construction of halido-bridged dinuclear copper(II) complexes with tridentate schiff bases

Article abstract of DOI:10.1080/15533174.2012.684237

Two new halido-bridged dinuclear copper(II) complexes, [Cu ₂Cl₂L₂]·1.5H₂O (1) and [Cu₂Br₂L₂]·H₂O (2), where L is the deprotonated form of the Schiff base 4-bromo-2-[(2-hydroxypropylimino) methyl]phenol, have been prepared and structurally characterized by elemental analysis, IR spectra, and single-crystal X-ray crystallography. Each Cu atom in the complexes is coordinated by three donor atoms of Schiff bases and by two halide atoms, forming a square pyramidal geometry. The Cl and Br atoms are preferred bridging groups for the construction of dinuclear copper complexes with Schiff bases. Copyright Taylor & Francis Group, LLC 2013.

Full text of DOI:10.1080/15533174.2012.684237

This article was downloaded by: [Laurentian University]
On: 08 October 2014, At: 10:13
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Synthesis and Reactivity in Inorganic, Metal-Organic,
and Nano-Metal Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/lsrt20
The Construction of Halido-Bridged Dinuclear
Copper(II) Complexes With Tridentate Schiff Bases
Shao-Song Qian a , Yao Lu 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: 12 Sep 2012.Published online: 03 Dec 2012.
To cite this article: Shao-Song Qian , Yao Lu , Zhong-Lu You & Hai-Liang Zhu (2013) The Construction of Halido-Bridged
Dinuclear Copper(II) Complexes With Tridentate Schiff Bases, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-
Metal Chemistry, 43:1, 107-110, DOI: 10.1080/15533174.2012.684237
To link to this article: http://dx.doi.org/10.1080/15533174.2012.684237
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the
Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and
should be independently verified with primary sources of information. Taylor and Francis shall not be liable for
any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever
or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of
the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:107–110, 2013
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.684237
The Construction of Halido-Bridged Dinuclear Copper(II)
Complexes With Tridentate Schiff Bases
Shao-Song Qian,1 Yao Lu,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
Br
N
Two new halido-bridged dinuclear copper(II) complexes,
OH
[Cu2Cl2L2]·1.5H2O (1) and [Cu2Br2L2]·H2O (2), where
L
OH
is the deprotonated form of the Schiff base 4-bromo-2-[(2-
hydroxypropylimino)methyl]phenol, have been prepared and
structurally characterized by elemental analysis, IR spectra, and
single-crystal X-ray crystallography. Each Cu atom in the com-
plexes is coordinated by three donor atoms of Schiff bases and by
two halide atoms, forming a square pyramidal geometry. The Cl
and Br atoms are preferred bridging groups for the construction
of dinuclear copper complexes with Schiff bases.
SCH. 1. The Schiff base HL.
EXPERIMENTAL
Materials and Measurements
Starting materials, reagents, and solvents with AR grade
were purchased from commercial suppliers and were used with-
out 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
spectrometer (Liaoning Normal University, China) as KBr pel-
lets 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).
Keywords crystal structure, Cu complex, 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 coordina-
tion chemistry. The rational design and construction of dinu-
clear complexes with Schiff bases are of particular interest in
coordination and structural chemistry. As is well known, the
halide and pseudohalide groups can link two or more metal
atoms, yielding various polynuclear complexes.[4–8] The search
in the Cambridge Crystallographic Database (CSD; version 5.32
with addenda up to February 2011)[9] has revealed that only 19
chlorido-bridged dinuclear copper complexes with Schiff bases
derived from salicylaldehyde and its derivatives have been re-
ported, and no such complexes with bromide bridges. In this
paper, two new dinuclear Schiff base copper(II) complexes
with chloride and bromide bridges, [Cu2Cl2L2]·1.5H2O (1) and
[Cu2Br2L2]·H2O (2), where L is the deprotonated form of the
Schiff base 4-bromo-2-[(2-hydroxypropylimino)methyl]phenol
(HL) (Scheme 1), were successfully prepared and characterized.
Synthesis of the Schiff Base
To the methanolic solution (30 mL) of 5-bromosali-
cylaldehyde (1.0 mmol, 0.201 g) was added a methanolic solu-
tion (30 mL) of 1-aminopropan-2-ol (1.0 mmol, 0.075 g) with
stirring. The mixture was stirred for 30 min at room temperature
to give yellow solution. The solvent was evaporated to give yel-
low powder, which was washed with cold methanol and dried in
air. Yield 92%. Characteristic IR data: 1635 cm−1. Anal. Calcd.
for C10H12BrNO2: C, 46.5; H, 4.7; N, 5.4. Found (%): C, 46.6;
H, 4.8; N, 5.5.
Synthesis of the Complexes
For [Cu2Cl2(L4)2]·1.5H2O (1), to the methanolic solution
(5 mL) of HL (0.1 mmol, 0.026 g) was added a methanolic
solution (5 mL) of CuCl2·2H2O (0.1 mmol, 0.017 g) with stir-
ring. The mixture was stirred for 10 min at room tempera-
ture, and then transferred to a stainless steel bomb, which was
sealed, heated at 150◦C for 12 h, and cooled gradually to room
temperature. Blue block-shaped crystals of 1, suitable for X-
ray crystal structural determination, were formed at the bottom
of the bomb. The crystals were isolated by filtration, washed
three times with methanol, and dried in air. Yield: 47%. Char-
acteristic IR data (cm−1): 1643 (s), 1180 (m). Anal. Calcd. for
Received 22 February 2012; accepted 8 April 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
107

108
S.-S. QIAN ET AL.
C20H25Br2Cl2Cu2N2O5.5: C, 32.5; H, 3.4; N, 3.8. Found (%):
C, 32.4; H, 3.6; N, 3.6.
X-Ray Crystallography
Diffraction intensities for the complexes were collected at
298(2) K using a Bruker SMART 1000 CCD area-detector
diffractometer (Shandong University of Technology, China)
with MoKα radiation (λ = 0.71073 Å). The collected data
were reduced with the SAINT program,[10] and multiscan ab-
sorption correction was performed using the SADABS.[11] The
structures were solved by direct methods. The complexes were
refined against F2 by full-matrix least-squares method using the
SHELXTL package.[12] All of the non-hydrogen atoms were
refined anisotropically. The water H atoms in 1 were located
from difference Fourier maps and refined isotropically, with
O–H and H···H distances restrained to 0.85(1) and 1.37(2) Å,
respectively. The remaining hydrogen atoms were placed in cal-
culated positions and constrained to ride on their parent atoms.
The crystallographic data for the complexes are summarized in
Table 1. Selected bond lengths and angles are given in Table 2.
For [Cu2Br2(L4)2]·H2O (2), complex 2 was synthesized by
the similar method as that described for 1, with CuCl2·2H2O
replaced by CuBr2 (0.022 g, 0.1 mmol). The blue block-
shaped single crystals of 2 were isolated, washed three times
with methanol, and dried in air. Yield: 33%. Characteris-
tic IR data (cm−1): 1643 (s), 1179 (m). Anal. Calcd. for
C20H24Br4Cu2N2O5: C, 29.3; H, 3.0; N, 3.4. Found (%): C,
29.5; H, 3.1; N, 3.3.
TABLE 1
Crystallographic and experimental data for complexes 1 and 2
Complex
Formula
1
2
C40H50Br4
Cl4Cu4N4O11
1478.4
C20H24Br4
Cu2N2O5
819.1
Mr
TABLE 2
Selected bond lengths (Å) and angles (◦)
T (K)
298(2)
298(2)
Crystal
shape/color
Crystal size
(mm3)
Crystal system
Space group
a (Å)
Block/blue
Block/blue
1
Cu1-O1
Cu1-N1
Cu1-Cl2
Cu2-O4
1.876 (7)
1.950 (8)
2.261 (3)
1.966 (7)
2.257 (3)
93.2 (3)
82.8 (3)
159.6 (3)
94.4 (2)
86.4 (2)
94.1 (4)
81.2 (4)
161.7 (3)
91.9 (2)
89.1 (2)
Cu1-O2
Cu1-Cl1
Cu2-O3
Cu2-N2
Cu2-Cl2
O1-Cu1-O2
O1-Cu1-Cl2
O2-Cu1-Cl2
N1-Cu1-Cl1
Cl2-Cu1-Cl1
O3-Cu2-O4
O3-Cu2-Cl1
O4-Cu2-Cl1
N2-Cu2-Cl2
Cl1-Cu2-Cl2
1.995 (7)
2.726 (3)
1.879 (8)
1.937 (9)
2.718 (3)
176.0 (3)
93.4 (2)
90.4 (2)
105.5 (2)
93.2 (1)
175.3 (3)
92.4 (2)
92.1 (2)
103.4 (2)
93.5 (1)
0.23×0.21×0.18
0.10×0.08×0.07
Monoclinic
P21/n
Monoclinic
P21/n
Cu2-Cl1
14.513(3)
7.818(2)
23.689(3)
92.218(2)
2685.8(10)
2
14.593(3)
8.037(2)
23.549(3)
90.03(2)
2761.8(9)
4
O1-Cu1-N1
N1-Cu1-O2
N1-Cu1-Cl2
O1-Cu1-Cl1
O2-Cu1-Cl1
O3-Cu2-N2
N2-Cu2-O4
N2-Cu2-Cl1
O3-Cu2-Cl2
O4-Cu2-Cl2
2
b (Å)
c (Å)
β (◦)
V (Å3)
Z
Dc (g cm−3
)
1.828
4.793
1.970
7.359
μ (Mo-Kα)
(mm−1
)
F(000)
1460
5754
1584
3565
Independent
reflections
Observed
Cu1-O1
Cu1-N1
Cu1-Br4
Cu2-O4
1.892 (9)
1.944 (11)
2.837 (2)
1.986 (8)
2.834 (2)
93.4 (5)
82.4 (4)
156.7 (3)
93.0 (3)
86.8 (2)
93.7 (5)
81.6 (5)
159.6 (4)
92.0 (3)
88.7 (2)
Cu1-O2
Cu1-Br3
Cu2-O3
Cu2-N2
Cu2-Br4
O1-Cu1-O2
O1-Cu1-Br3
O2-Cu1-Br3
N1-Cu1-Br4
Br3-Cu1-Br4
O3-Cu2-O4
O3-Cu2-Br4
O4-Cu2-Br4
N2-Cu2-Br3
Br4-Cu2-Br3
1.989 (8)
2.415 (2)
1.910 (10)
1.945 (13)
2.407 (2)
175.6 (4)
94.1 (3)
90.2 (2)
105.2 (3)
96.4 (1)
175.3 (4)
92.9 (3)
91.7 (3)
102.4 (3)
96.7 (1)
2141
1553
reflections (I ≥
2σ(I))
Min. and max.
transmission
Parameters
Restraints
Goodness-of-fit
on F2
0.405 and 0.479
0.526 and 0.627
Cu2-Br3
O1-Cu1-N1
N1-Cu1-O2
N1-Cu1-Br3
O1-Cu1-Br4
O2-Cu1-Br4
O3-Cu2-N2
N2-Cu2-O4
N2-Cu2-Br4
O3-Cu2-Br3
O4-Cu2-Br3
318
19
0.950
300
0
0.819
R1, wR2 [I ≥
0.0688, 0.1725
0.1981, 0.2347
ꢀ
0.0604, 0.1202
0.1386, 0.1405
2σ(I)]a
R1, wR2 (all
data)a
ꢀ
aR1 = Fo – Fc/Fo, wR2 = [ w(Fo2 – Fc2)/ w(Fo ) ]
2 2 1/2

HALIDO-BRIDGED DINUCLEAR COPPER(II) COMPLEXES
109
Structure Description of the Complexes
The single-crystal X-ray diffraction shows that the complexes
are structurally similar halido-bridged dinuclear copper(II) com-
pounds (Figure 1 for 1, Figure 2 for 2). The asymmetric unit
of the complex 1 contains a dichlorido-bridged dinuclear cop-
per(II) complex molecule and 1.5 water molecules of crys-
tallization. The asymmetric unit of the complex 2 contains a
dibromido-bridged dinuclear copper(II) complex molecule and
a water molecule of crystallization. The Cu···Cu distances are
3.377(1) Å in 1, and 3.434(1) Å in 2, which are within the val-
ues observed in the 19 chlorido-bridged Schiff base copper(II)
complexes in CSD.
In the complexes, 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 complexes
is five-coordinated in a square pyramidal geometry, with the
basal plane defined by the NNO donor atoms of the Schiff base
ligand, and by one Cl or Br atom, and with the apical position
occupied by another halide atom. The average trans angles are
167.8(2)◦ for Cu1 and 168.5(2)◦ for Cu2 in 1, and 166.2(3)◦
for Cu1 and 167.4(3)◦ for Cu2 in 2. The Cu atoms deviate
from the least-squares planes defined by the four basal donor
atoms by 0.178(1) Å for Cu1, and 0.159(1) Å for Cu2 in 1,
and 0.201(1) Å for Cu1, and 0.183(1) Å for Cu2 in 2, toward
the apical donor atoms. The coordinate bond lengths related to
the Cu atoms in both complexes are comparable to each other
and also comparable to the corresponding values observed in
other similar halido-bridged copper(II) complexes with Schiff
bases.[4,13–17]
The coordination number 5 for copper(II) complexes is very
common. The question arises as to whether the coordination
polyhedra around the Cu atoms can be described as distorted
square pyramid or trigonal bipyramid. Further information can
be obtained by determining the structural index τ,[18] which
represents the relative amount of trigonality (square pyramid,
τ = 0; trigonal bipyramid, τ = 1); τ = (β – α)/60◦, α and β
FIG. 1. A perspective view of the molecular structure of 1 with the atom
labeling scheme. The thermal ellipsoids are drawn at the 30% probability level.
RESULTS AND DISCUSSION
Chemistry
The Schiff base HL was synthesized by the reaction
of equimolar quantities of 5-bromosalicylaldehyde with 1-
aminopropan-2-ol in methanol. The air-stable yellow product of
the Schiff base is soluble in DMSO, DMF, methanol, ethanol,
acetonitrile, and chloroform, and insoluble in water. The ele-
mental analyses are in good agreement with the chemical for-
mula proposed for the compound. The complexes 1 and 2 were
synthesized by the reaction of the Schiff base with CuCl2·2H2O
or CuBr2 in methanol at solvothermal condition. All the com-
plexes are stable in air at room temperature for at least two
months.
FIG. 2. A perspective view of the molecular structure of 2 with the atom labeling scheme. The thermal ellipsoids are drawn at the 30% probability level.

110
S.-S. QIAN ET AL.
being the two largest angles around the metal atom. The values
of τ are 0.27 (Cu1) and 0.23 (Cu2) in 1, and 0.32 (Cu1) and
0.26 (Cu2) in 2. From the τ values, it can be concluded that all
the Cu atoms in the complexes adopt distorted square pyramidal
coordination.
3. Peng, S.-J.; Zeng, J.-L.; Wei, C.; Fang, F. Synthesis and crystal structure of a
phenolato-bridged dinuclear oxovanadium(V) complex derived from Nꢁ–[1-
(2-hydroxyphenyl)ethylidene]-1H-indole-3-carbohydrazide. Synth. React.
Inorg. Met.-Org. Nano-Met. Chem. 2011, 41, 1052–1055.
4. Thakurta, S.; Roy, P.; Rosair, G.; Go´mez-Garc´ıa, C.J.; Garribba, E.; Mitra,
S. Ferromagnetic exchange coupling in a new bis(mu-chloro)-bridged cop-
per(II) Schiff base complex: Synthesis, structure, magnetic properties and
catalytic oxidation of cycloalkanes. Polyhedron 2009, 28, 695–702.
5. Nepveu, F.; Bormuth, F.-J.; Walz, L. Synthesis, X-ray structure, and
magnetic-properties of di-μ-chloro-bis-[N-(2-hydroxy-2-phenylethyl)sali-
cylideneiminatocopper(II)]. J. Chem. Soc., Dalton Trans. 1986, 1213–1216.
6. Bluhm, M.E.; Ciesielski, M.; Gorls, H.; Walter, O.; Doring, M. Com-
plexes of Schiff bases and intermediates in the copper-catalyzed oxidative
heterocyclization by atmospheric oxygen. Inorg. Chem. 2003, 42, 8878–
8885.
IR Spectra
In the IR spectra of the complexes, the strong absorption
bands at ca. 1644 cm−1 for 1 and 2 can be assigned to the
azomethine stretching frequencies of the Schiff base ligands,
whereas for the free Schiff bases the corresponding bands are
observed at 1635 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 bands at 1178–1180 cm−1 for the complexes. The
weak bands indicative of the Cu–O, Cu–N, Cu–Cl, and Cu–Br
7. You, Z.-L.; Zhu, H.-L. Syntheses, crystal structures, and antibacterial activ-
ities of four Schiff base copper(II), zinc(II), and cadmium(II) complexes de-
rived from 2–[(2-dimethylaminoethylimino)methyl]phenol. Z. Anorg. Allg.
Chem. 2006, 632, 140–146.
bonds are located in the region 600–300 cm−1
.
8. Manzur, J.; Garcia, A.M.; Vega, A.; Ibanez, A. Synthesis and structure of
copper (II) complexes with L-OH (L-OH = 2,6-bis–[N-(2-pyridylethyl)-
formidoyl]-4-methyl-phenol). Polyhedron 2007, 26, 115–122.
9. Allen, F.H. The Cambridge Structural Database: a quarter of a million
crystal structures and rising. Acta Crystallogr. 2002, B58, 380–388.
10. Bruker. SMART and SAINT; Bruker AXS Inc., Madison, WI, 2002.
11. Sheldrick, G.M. SADABS: Program for Empirical Absorption Correction
of Area Detector; University of Go¨ttingen, Go¨ttingen, Germany, 1996.
12. Sheldrick, G.M. SHELXTL V5.1 Software Reference Manual; Bruker AXS,
Inc., Madison, WI, 1997.
CONCLUSION
Here we reports the synthesis and crystal structures of two
new halido-bridged dinuclear copper(II) complexes with a tri-
dentate Schiff base ligand. Complex 2 is the first reported
bromido-bridged dinuclear Schiff base copper(II) compound.
The Cl and Br anions are preferred bridging groups for the
construction of dinuclear copper(II) complexes with tridentate
Schiff bases.
13. Liu, H.-Y.; Gao, F.; Niu, D.-Z.; Tian, J.-L. Chlorido-bridged polymeric and
dinuclear copper(II) complexes with tridentate Schiff base: synthesis, crys-
tal structure and magnetic properties. Inorg. Chim. Acta 2009, 362, 4179–
4184.
14. Chumakov, Y.M.; Tsapkov, V.I.; Filippova, I.G.; Bocelli, G.; Gulea, A.P.
Crystalstructuresofcopper(II)and nickel(II)nitrateand chloride complexes
with 4-bromo-2–[(2-hydroxyethylimino)-methyl]phenol. Crystallogr. Rep.
2008, 53, 619–625.
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.; Reedijk, J. Coordination compounds from the planar tridentate Schiff-
base ligand 2-methoxy-6-((quinolin-8-ylimino)methyl)phenol (mqmpH)
with several transition metal ions: Use off [FeIII(mqmp)(CH3OH)Cl2] in
the catalytic oxidation of alkanes and alkenes. Polyhedron 2010, 29, 2291–
2296.
SUPPLEMENTARY MATERIALS
CCDC 843683 (1) and 843684 (2) contain the supplemen-
tary crystallographic data for this paper. These data can be
obtained free of charge 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: deposit@ccdc.cam.ac.uk.
REFERENCES
1. Yildiz, E.; Cetinkol, T.; Serindag, O. Synthesis and characterization of
mono- and dinuclear metal complexes with novel azo compounds and their
dyeing properties. Synth. React. Inorg. Met.-Org. Nano-Met. Chem. 2010,
40, 19–26.
17. Adams, H.; Fenton, D.E.; Haque, S.R.; Heath, S.L.; Ohba, M.; Okawa, H.;
Spey, S.E. Diversity in the reactions of unsymmetric dinucleating Schiff
base ligands with Cu-II and Ni-II. J. Chem. Soc., Dalton Trans. 2000,
1849–1856.
2. Hui, R.-H.; Zhou, P.; You, Z.-L. Syntheses and crystal structures of
two end-on thiocyanato-bridged dinuclear copper(II) complexes derived
from 2–[(2-ethylaminoethylimino)methyl]phenol and 2,4-dichloro-6-[(2-
methylaminoethylimino)methyl]phenol. Synth. React. Inorg. Met.-Org.
Nano-Met. Chem. 2009, 39, 495–499.
18. Addison, A.W.; Rao, T.N.; Reedijk, J.; van Rijn, J.; Verschoor, G.C. Synthe-
sis, structure, and spectroscopic properties of copper(II) compounds con-
taining nitrogen sulfur donor ligands – The crystal and molecular-structure
of aqua[1,7-bis(N-methylbenzimidazol-2ꢁ-yl)-2,6-dithiaheptane]copper(II)
perchlorate. J. Chem. Soc., Dalton Trans. 1984, 1349–1356.