Synthesis, characterization and crystal structure of a mononuclear copper(II) complex derived from 2-methoxy-6-[(pyridin-2-ylmethylimino)methyl] phenol

Article abstract of DOI:10.1007/s10870-010-9718-6

Blue needle-shaped crystals of bromo{2-methoxy- 6-[(pyridin-2- ylmethylimino)methyl]phenolate}copper( II), [CuBr(C₁₄H ₁₃N₂O₂)], have been obtained and characterized by elemental analysis, IR spectrum, and single

Full text of DOI:10.1007/s10870-010-9718-6

J Chem Crystallogr (2010) 40:672–674
DOI 10.1007/s10870-010-9718-6
ORIGINAL PAPER
Synthesis, Characterization and Crystal Structure
of a Mononuclear Copper(II) Complex Derived
from 2-Methoxy-6-[(pyridin-2-ylmethylimino)methyl]phenol
Xiao-Ling Wang
Cheng-Lu Zhang
•
Zhong-Lu You
•
Xiao Han
•
Received: 23 July 2006 / Accepted: 16 January 2010 / Published online: 2 February 2010
Ó Springer Science+Business Media, LLC 2010
Abstract Blue needle-shaped crystals of bromo{2-meth-
oxy-6-[(pyridin-2-ylmethylimino)methyl]phenolate}cop-
per(II), [CuBr(C H N O )], have been obtained and
the multi-copper oxidases. The Cu center found in nitrous
A
oxide reductase and cytochrome c oxidase is a delocalized
mixed-valence dicopper center [9, 10]. Many model com-
plexes of transition metals with various ligands have been
prepared and characterized [11–13]. Some of these model
complexes are potent antiviral agents, and some have been
used as catalysts [14, 15]. Schiff base complexes play an
important role in the development of coordination chem-
istry related to catalysis, enzymatic reactions and molecu-
lar architectures [16–18]. In this paper, we report the
synthesis and structure of a mononuclear copper(II) com-
plex derived from the Schiff base 2-methoxy-6-[(pyridin-2-
ylmethylimino)methyl]phenol.
1
4 13 2 2
characterized by elemental analysis, IR spectrum, and
single crystal X-ray diffraction. The complex crystallizes in
the monoclinic space group P2 /c with unit cell dimensions
1
˚
˚
˚
a = 7.059(1) A, b = 18.504(3) A, c = 10.664(2) A, b =
´
3
˚
1
05.415(2)°, V = 1,342.8(4) A , Z = 4, R = 0.0377 and
1
wR = 0.0751. X-ray structural determination revealed
2
that the molecule of the mononuclear copper(II) complex is
nearly coplanar. The Cu atom in the complex is tetra-
coordinated by one phenolate O atom, one imine N atom,
and one pyridine N atom of the Schiff base ligand, and
by one terminal Br atom, forming a square planar
coordination.
Experimental
Keywords Schiff base Á Copper(II) complex Á Synthesis Á
Coordination chemistry
Materials and Measurements
All chemicals (reagent grade) were commercially available
and were used without further purification. C, H, and N
elemental analyses were performed on a Perkin-Elmer
240C elemental analyzer. The IR spectrum was measured
with a FT-IR 170-SX (Nicolet) spectrophotometer.
Introduction
Copper-containing metalloproteins are widely found in
nature. Among them are two classes of copper-containing
metalloproteins responsible for rapid intra- and inter-
molecular electron transfer in biological systems: those
containing mononuclear blue copper sites [1–5] and those
containing dinuclear CuA centers [6–8]. The blue copper
center, is found in plastocyanin, azurin, stellacyanin, and
Synthesis of the Complex CuBr(C H N O )
14 13 2 2
3-Methoxysalicylaldehyde (0.1 mmol, 15.2 mg) and 2-ami-
nomethylpyridine (0.1 mmol, 10.8 mg) were dissolved in
MeOH (10 mL). The mixture was stirred at room temper-
ature for 30 min to give a clear yellow solution. To this
solution was added dropwise an aqueous solution (2 mL) of
X.-L. Wang Á Z.-L. You (&) Á X. Han Á C.-L. Zhang
Department of Chemistry and Chemical Engineering,
Liaoning Normal University, Huanghe Road 850#,
CuBr (0.1 mmol, 22.3 mg) with stirring. The resulting
2
mixture was stirred for another 30 min at room temperature.
After keeping the filtrate in air for 8 days, blue needle-like
116029 Dalian, People’s Republic of China
e-mail: youzhonglu@yahoo.com.cn
1
23

J Chem Crystallogr (2010) 40:672–674
673
´
˚
Table 1 Crystal data and refinement parameters for the complex
Table 2 Selected bond distances (A) and angles (°) for the complex
CCDC deposit no.
Molecular formula
Molecular weight
Temperature (K)
Radiation k
615679
13BrCuN
Bond distances
C
14
H
2
O
2
Cu1–O1
1.904(2)
2.017(3)
Cu1–N1
Cu1–Br1
1.933(3)
384.71
298 (2)
Cu1–N2
2.3970(6)
Bond angles
O1–Cu1–N1
N1–Cu1–N2
N1–Cu1–Br1
´
˚
Mo Ka (0.71073 A)
92.2(1)
82.4(1)
O1–Cu1–N2
O1–Cu1–Br1
N2–Cu1–Br1
174.5(1)
89.0(1)
96.4(1)
Crystal system
Monoclinic
Space group
P2
1
/c
175.2(1)
´
˚
a (A)
7.059(1)
´
˚
b (A)
18.504(3)
2
on F by full-matrix least-squares method using the
SHELXTL package [20]. All of the non-hydrogen atoms
were refined anisotropically. H atoms were placed in cal-
culated positions and constrained to ride on their parent
atoms. The details of the crystallographic data are sum-
marized in Table 1. Selected bond lengths and angles are
summarized in Table 2.
´
˚
c (A)
10.664(2)
b (°)
105.415(2)
´
3
V (A )
˚
1,342.8(4)
Z
4
-
3
)
D
calc (g cm
1.903
Crystal size (mm)
0.17 9 0.04 9 0.04
Crystal colour
Blue
-
1
)
Absorption coefficient (mm
4.603
Absorption correction Tmin and Tmax
F(000)
0.508 and 0.837
Results and Discussion
764
Reflections collected/unique
Range/indices (h, k, l)
h limit (°)
No. of observed data, I [ 2r(I)
No. of variables
8,057/3,081 [Rint = 0.0460]
Crystal Structure Description of the Complex
-9, 9; -24, 14; -13, 13
2.20–27.50
Figure 1 gives a perspective view of the complex with the
atomic labeling system. The complex is a mononuclear
copper(II) compound, in which the non-hydrogen atoms of
the molecule is nearly coplanar, with the mean deviation
2,131
182
No. of restraints
0
2
Goodness of fit on F
˚
Largest diff. Peak and hole (e A
0.983
˚
from plane by 0.039(2) A. The Cu atom in the complex is
-
3
)
0.427 and -0.416
0.0377, 0.0751
tetra-coordinated by one phenolate O atom, one imine N
atom, and one pyridine N atom of the Schiff base ligand,
and by one terminal Br atom, forming a square planar
coordination. The bond lengths related to the Cu centre are
within normal ranges and are similar to the corresponding
distances observed in other similar Schiff base copper(II)
a
R
R
a
1
, wR
2
[I C 2r(I)]
a
1
, wR (all data)
P
2
0.0673, 0.0865
P
P
P
2
= [ w(Fo - Fc ) / w(Fo ) ]
2 2
2 2 1/2
R
1
=
||Fo| - |Fc||/ |Fo|, wR
2
w = [r (Fo) ? (0.0343(Fo ? 2Fc )/3) ]
2
,
2
2
2
2 -1
crystals of the complex, suitable for single crystal X-ray
diffraction, formed at the bottom of the vessel on slow
evaporation of the solvent. The crystals were isolated,
washed three times with cold MeOH and dried in a vacuum
complexes [21–23]. The trans angles in the CuBrN O
2
square plane deviate from linearity by 5.5(1)° and 4.8(1)°,
respectively; and all other angles are close to 90°, ranging
desiccator containing anhydrous CaCl . Analysis calculated
2
for C H BrCuN O : C, 43.7; H, 3.4; N, 7.3%; found: C,
13
1
4
2 2
-
1
4
3.6; H, 3.5; N, 7.2%. Selected IR data (KBr, cm ): 3423
m), 3060 (w), 2933 (w), 2834 (w), 1637 (vs), 1598 (s),
(
1
1
4
538 (w), 1472 (m), 1440 (s), 1379 (vs), 1318 (s), 1240 (s),
220 (m), 1082 (m), 1060 (m), 972 (m), 862 (w), 730 (m),
83 (w), 433 (w).
Crystal Structure Determination
X-ray diffraction intensities were collected using a Bruker
SMART 1000 CCD area detector equipped with a graphite-
´
˚
monochromated Mo–Ka radiation (k = 0.71073 A) at
2
Fig. 1 Molecular structure of the complex. Displacement ellipsoids
are drawn at the 30% probability level and H atoms are shown as
small spheres of arbitrary radii; numbering according to Table 2
98(2) K. Absorption correction was applied by SADABS
[
19]. The structure was solved by direct method and refined
123

6
74
J Chem Crystallogr (2010) 40:672–674
to imitate the active center of the copper-containing
metalloproteins.
Supplementary Material
CCDC-615679 contains the supplementary crystallographic
data for this paper. These data can be obtained free of
charge at http://www.ccdccam.ac.uk/const/retrieving.html
or from the Cambridge Crystallographic Data Centre
(CCDC), 12 Union Road, Cambridge CB2 1EZ, UK; fax:
?
44(0)1223-336033 or e-mail: deposit@ccdc.cam.ac.uk.
Acknowledgments This work was financially supported by the
Education Office of Liaoning Province (Project No. 2008T107).
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The present study shows that the Schiff base 2-methoxy-6-
[
(pyridin-2-ylmethylimino)methyl]phenol coordinates to
the Cu atom through the phenolate O atom, the imine N
atom and the pyridine N atom, while the ether O atom of
the Schiff base is not coordinate to the Cu atom. The
coordination of the Cu atom in the complex is different
from those in the mononuclear blue copper sites and those
20. Sheldrick GM SHELXTL V5.1 Software reference manual.
Bruker AXS, Madison
2
2
2
1. You Z-L, Zhu H-LZ (2006) Anorg Allg Chem 632:140
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in the dinuclear Cu centers. Further work needs to be done
A
1
23