metal-organic compounds
atom from the mean O4 plane. We have tabulated some
available data for complexes of the type [Cu2(C6H5COO)4L2]
(L = pyridine or substituted pyridine) in Table 2, with a view to
seeing how well the earlier conclusions hold true for the
tetrabenzoates of copper(II). As can be seen from the data,
there are several compounds for which there is no correlation
of the above nature. On the other hand, it is observed from the
tabulated data that whenever there are substituents on the 2-
and/or 6-position of the axial pyridine ligand, the CuÐN
distance is relatively long. Again, with the exception of
[Cu2(C6H5COO)4(4,7-dichloroquinoline)2], the CuÁ Á ÁCu
distances are also long in complexes having ligands of this
type. This suggests that steric factors due to the apical ligand
may in¯uence the CuÁ Á ÁCu as well as the CuÐN distances.
The distorted nature of the CuO4N square pyramid can be
understood from the OÐCuÐO and OÐCuÐN angles. While
the former are in the range 88.08 (6)±166.41 (5)ꢀ, the latter are
in the range 89.88 (6)±103.85 (6)ꢀ. The deviations from lin-
earity of the two OÐCuÐO angles (' 166ꢀ) for the two pairs
of trans O atoms are particularly notable. However, the angles
and bonds in the copper coordination environment in (I) are
Experimental
CuCl2Á2H2O (0.34 g, 2 mmol) was dissolved in methanol (25 ml). To
this solution, sodium benzoate (C6H5COONa; 0.576 g, 4 mmol) was
added and the mixture was stirred for ca 10 min to obtain a green±
blue solution. 4-(Dimethylamino)pyridine (0.488 g, 4 mmol) was
added and the mixture was stirred for an additional 2 h. The resulting
green product was ®ltered off, washed with small volumes of
methanol and dried in a vacuum desiccator over fused CaCl2 (yield
75%). Single crystals of (I) suitable for X-ray diffraction were
obtained from a methanol solution of the title complex by slow
evaporation.
Crystal data
3
Ê
[Cu2(C7H5O2)4(C7H10N2)2]
Mr = 855.86
V = 1981.71 (10) A
Z = 2
Monoclinic, P21=n
Mo Kꢂ radiation
1
Ê
Ê
a = 10.4339 (3) A
ꢀ = 1.13 mm
T = 293 (2) K
b = 11.1284 (3) A
Ê
c = 17.1616 (5) A
0.33 Â 0.30 Â 0.22 mm
ꢁ = 96.0140 (1)ꢀ
Data collection
Bruker SMART CCD area-detector
diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.707, Tmax = 0.789
19035 measured re¯ections
4112 independent re¯ections
3511 re¯ections with I > 2ꢃ(I)
Rint = 0.019
Â
of comparable magnitude vis a vis the corresponding values
found for several [Cu2(C6H5COO)4L2] compounds (Kawata et
al., 1992).
Ê
The Cu atom is 0.1878 (6) A from the mean plane formed
by the four equatorial O atoms. On the other hand, the
coordinated N atom also lies in the same direction, at a
Re®nement
R[F2 > 2ꢃ(F2)] = 0.026
wR(F2) = 0.072
S = 1.03
253 parameters
H-atom parameters constrained
3
Ê
Áꢄmax = 0.28 e A
3
Ê
0.27 e A
Ê
4112 re¯ections
Áꢄmin
=
distance of 2.312 (1) A from the plane. The dihedral angle
between the planes through Cu1/O2/C15/O3/Cu1i/O2i/C15i/
O3i and Cu1/O1/C8/O4/Cu1i/O1i/C8i/O4i [symmetry code: (i)
x, 1 y, z] is 88.74 (3)ꢀ, which is close to the ideal value of
90ꢀ, the observed difference being attributable to packing
effects in a crystal of low symmetry. The corresponding value
Table 1
Selected geometric parameters (A, ).
ꢀ
Ê
Cu1ÐO4i
Cu1ÐO2
Cu1ÐO3i
Cu1ÐO1
Cu1ÐN1
1.9711 (12)
1.9726 (13)
1.9791 (13)
1.9796 (12)
2.1410 (14)
Cu1ÐCu1i
O1ÐC8
O2ÐC15
O3ÐC15
O4ÐC8
2.6982 (4)
1.255 (2)
1.255 (2)
1.250 (2)
1.258 (2)
for the complex [Cu2(C6H5COO)4(N,N-diethylnicotin-
ꢀ
È
amide)2] (Hokelek et al., 1995) is 88.9 (1) .
Following the method given by Kawata et al. (1992), the
rotation angles of the phenyl group relative to the carboxyl
group in the bridging benzoate ions, 'rot, and the bending
angles of the COO group relative to the CuÐOÁ Á ÁOÐCu
plane, 'bend, can be calculated. For an isolated binuclear
complex, the 'rot and 'bend values are expected to be close to
zero (with minimum strain energy). However, in the present
structure, (I), the corresponding values are 3.85 (31) and
15.66 (21)ꢀ, and 3.71 (28) and 0.91 (25)ꢀ, respectively. The
deviation of these values from zero is likely to be a conse-
quence of the molecular packing in the crystal lattice. The
deviations lead to an improvement in packing effeciency. In
such cases, the increased intermolecular strain is compensated
for by favourable intermolecular interactions.
The comparison of bond lengths and angles observed here
for compound (I) and those reported previously by Zhang et
al. (2003) shows that, while the crystallographic and geometric
parameters are very similar, the s.u. values and the residuals
observed in the present work are much improved. This
improvement is an outcome of the use of a greater number of
re¯ections in the present work. Moreover, the intensity data
used earlier were not corrected for absorption effects.
O4iÐCu1ÐO2
O4iÐCu1ÐO3i
O2ÐCu1ÐO3i
O4iÐCu1ÐO1
O2ÐCu1ÐO1
O3iÐCu1ÐO1
89.42 (6)
88.08 (6)
166.26 (6)
166.41 (5)
88.73 (6)
90.53 (6)
O4iÐCu1ÐN1
O2ÐCu1ÐN1
O3iÐCu1ÐN1
O1ÐCu1ÐN1
O1ÐC8ÐO4
O3ÐC15ÐO2
97.89 (6)
103.85 (6)
89.88 (6)
95.62 (5)
125.49 (16)
125.66 (16)
Symmetry code: (i) x; y 1; z.
Structure determination work was carried out using the WinGX
platform (Farrugia, 1999). All H atoms belonging to the phenyl
groups of the benzoate ligands and to the pyridine ring of the DMAP
Ê
ligand were placed in calculated positions, with CÐH = 0.93±0.96 A
and Uiso(H) = 1.2 or 1.5 times Ueq(C). No restraints were applied for
any other parameters during structure re®nement.
Data collection: SMART (Bruker, 1997); cell re®nement: SMART;
data reduction: SAINT (Bruker, 1997); program(s) used to solve
structure: SHELXS97 (Sheldrick, 1997); program(s) used to re®ne
structure: SHELXL97 (Sheldrick, 1997); molecular graphics:
ORTEPIII (Burnett & Johnson, 1996); software used to prepare
material for publication: publCIF (Westrip, 2007).
Financial support from the Department of Science and
Technology, India (grant No. SR/S1/IC-51/2003), is gratefully
ꢁ
Acta Cryst. (2007). C63, m392±m394
Bora et al.
[Cu2(C7H5O2)4(C7H10N2)2] m393
Bora, Sanchay Jyoti
