Di-μ-chlorido-bis[(2-aminobenzamide-κ2 N 2,O)chloridocopper(II)]

The title compound, [Cu2Cl4(C7H8N2O)2], crystallizes as discrete [CuLCl2]2 (L = 2-aminobenzamide) dimers with inversion symmetry. Each CuII ion is five-coordinated and is bound to two bridging chloride ligands, a terminal chloride ligand and a bidentate 2-aminobenzamide ligand. The crystal structure exhibits alternating layers parallel to (010) along the b-axis direction. In the crystal, the components are linked via N—H⋯Cl hydrogen bonds, forming a three-dimensional network. These interactions link the molecules within the layers and also link the layers together and reinforce the cohesion of the structure.

The title compound, [Cu 2 Cl 4 (C 7 H 8 N 2 O) 2 ], crystallizes as discrete [CuLCl 2 ] 2 (L = 2-aminobenzamide) dimers with inversion symmetry. Each Cu II ion is five-coordinated and is bound to two bridging chloride ligands, a terminal chloride ligand and a bidentate 2-aminobenzamide ligand. The crystal structure exhibits alternating layers parallel to (010) along the b-axis direction. In the crystal, the components are linked via N-HÁ Á ÁCl hydrogen bonds, forming a three-dimensional network. These interactions link the molecules within the layers and also link the layers together and reinforce the cohesion of the structure.

Related literature
For general background to 2-aminobenzamide derivatives, see: Nagaoka et al. (2006); Butsch et al. (2011); Kapoor et al. (2010). For related structures, see: Yang et al. (2012); Lah et al. (2006). For standard bond lengths, see: Allen (2002) Experimental Crystal data [Cu 2 Cl 4 (C 7 Table 1 Hydrogen-bond geometry (Å , ).  2-aminobenzamide derivatives are well known compounds as anticancer agents (Nagaoka et al., 2006). In addition, it was reported that some 2-aminobenzamide derivatives possessed biological activities, such as Anti-herpes simplex virus activity (Yang et al., 2012). As part of our ongoing studies of complexes based on copper and derivates we report here synthesis and the crystal structure of the title compound, obtained by the reaction of 2-aminobenzamide ligand with copper(II) chloride. The molecular structure of (I), and the atomic numbering used, is illustrated in Fig. 1. The asymmetric unit of (I) consists of one-half of the molecule, with the other half generated by a crystallographic inversion center. All bond distances and angles are within the ranges of accepted values(CSD, Allen, 2002) The complex contain five-coordinate Cu atoms ( Fig. 1) with may be described either as square pyramidal with C11 apically bound to a pseudoplanar Cu1-O1-C12-Cl1a-N1 (a:-x, -y,1 -z) fragment or as trigonal bipyramidal with N1 and Cl1a apical (Butsch et al., 2011;Kapoor et al., 2010). The Cu atoms are linked by double Cl atoms bridges, resulting in the formation of dimer. The two Cu atoms, separated by 3.430 (1) Å, are doubly bridged by two chlorido ligands. The bridge is far from symmetrical with Cu-Cl1 and Cu-Cl1a (with a: -x, -y,1 -z) distances of 2.3983 (5) and 2.2990 (6) Å, respectively, and a Cu-Cl1-Cua bridging angle of 93.77 (2)°. The 2-aminobenzamide ligand binds to a single Cu metal ion within the dimer in a chelating manner [Cu-N1: 1.9923 (15) Å and Cu-O1: 2.0988 (13) Å]. The fifth coordination site is occupied by a terminal chlorido ligand at a distance of 2.3043 (6) Å (Lah et al., 2006).
The crystal structure exhibit alternating layers parallel to (010) plane along the b axis (Fig. 2). In the crystal, the components of the structure are linked via intermolecular N-H···Cl hydrogen bonds to form a three-dimensional network (Table1 and Fig.2) These interaction bonds link the molecules within the layers and also link the layers together and reinforcing the cohesion of the structure.

Experimental
An aqueous acidic solution of copper(II) chloride was added to an aqueous solution of the 2-aminobenzamide ligand (L) (1:l mol ratio). The mixture was then stirred for several hours during which time darkish green crystals of [CuLCl 2 ] 2 were deposited. This crystalline product was collected and washed with ether and was carefully isolated under polarizing microscope for analysis by X-ray diffraction.

Refinement
All non-H atoms were refined with anisotropic atomic displacement parameters. The remaining H atoms were localized on Fourier maps but introduced in calculated positions and treated as riding on their parent atoms (C and N) with C-H=0.95 Å and N-H=0.88 or 0.92 Å and U iso (H)=1.2U eq (C or N).

Special details
Experimental. Absorption correction: empirical using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm CrysAlis PRO (Agilent, 2011). Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles 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.