Bis(3-chlorobenzoato-κ2 O,O′)bis(nicotinamide-κN)copper(II)

The molecule of the title CuII complex, [Cu(C7H4ClO2)2(C6H6N2O)2], contains two 3-chlorobenzoate (CB) and two nicotinamide (NA) ligands; the CB act as bidentate ligands, while the NA are monodentate ligands. The resulting CuN2O4 coordination polyhedron is a considerably distorted octahedron. The dihedral angles between the carboxylate groups and the adjacent benzene rings are 17.92 (12) and 24.69 (16)°, while the two benzene rings and the two pyridine rings are oriented at dihedral angles of 52.20 (8) and 1.56 (6)°. In the crystal, N—H⋯N and C—H⋯O hydrogen bonds link the molecules into a three–dimensional network. The π–π contact between the benzene rings [centroid–centroid distance = 3.982 (2) Å] may further stabilize the crystal structure.

In the monomeric title complex, I, the Cu II ion is surrounded by two 3-chlorobenzoate (CB) and two (NA)  In the title compound ( Fig. 1), the Cu atom is displaced out of the least-squares planes of the carboxylate groups  (Hökelek et al., 1996) and 55.2 (1)° in [Cu(Asp) 2 (Py) 2 ], where Asp is acetylsalicylate and Py is pyridine, VIII, (Greenaway et al., 1984).
In the crystal structure, intermolecular N-H···O and C-H···O hydrogen bonds (Table 1) link the molecules into a three-dimensional network, in which they may be effective in the stabilization of the structure. The π-π contact between the benzene rings, Cg2···Cg2 i , where Cg2 is the centroid of the ring B (C9-C14) may further stabilize the structure, with Cg···Cg distance of 3.982 (2)Å. Symmetry code: (i) -x, 1-y, -z.

Experimental
The title compound was prepared by the reaction of CuSO 4 . 5H 2 O (1.25 g, 5 mmol) in H 2 O (50 ml) and NA (1.22 g, 10 mmol) in H 2 O (50 ml) with sodium 3-chlorobenzoate (1.79 g, 10 mmol) in H 2 O (100 ml). The mixture was filtered and set aside to crystallize at ambient temperature for one week, giving blue single crystals.

Refinement
Atoms H2A, H2B, H4A and H4B (NH 2 groups) were located in a difference Fourier map and refined isotropically. The remaining H atoms were positioned geometrically with C-H = 0.93Å for aromatic H atoms, and constrained to ride on supplementary materials sup-2 . E69, m356-m357 their parent atoms, with U iso (H) = 1.2U eq (C).

Figure 1
The molecular structure of the title compound with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as a small spheres of arbitrary radius.  Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.