{4,4′,6,6′-Tetrachloro-2,2′-[2,2-dimethylpropane-1,3-diylbis(nitrilomethanylylidene)]}copper(II)

In the title Schiff base complex, [Cu(C19H16Cl4N2O2)], the geometry around the CuII atom is distorted square-planar defined by the N2O2 donor atoms of the coordinated ligand. The dihedral angle between the substituted benzene rings is 29.95 (16)°. In the crystal, molecules are linked along the b axis, forming individual dimers through C—H⋯O interactions. The crystal structure is further stabilized by intermolecular π–π interactions [centroid–centroid distance = 3.6131 (17) Å].

In the title Schiff base complex, [Cu(C 19 H 16 Cl 4 N 2 O 2 )], the geometry around the Cu II atom is distorted square-planar defined by the N 2 O 2 donor atoms of the coordinated ligand. The dihedral angle between the substituted benzene rings is 29.95 (16) . In the crystal, molecules are linked along the b axis, forming individual dimers through C-HÁ Á ÁO interactions. The crystal structure is further stabilized by intermolecularinteractions [centroid-centroid distance = 3.6131 (17) Å ].

Comment
Schiff base complexes are one of the most important stereochemical models in transition metal coordination chemistry, with the ease of preparation and structural variations (Granovski et al., 1993;Blower et al., (1998). In continuation of our work on the crystal structure of Schiff base metal complexes (Kargar et al., 2012;Kargar et al., 2011;Ghaemi, et al., (2011), we determined the X-ray structure of the title compound.
The asymmetric unit of the title compound, Fig. 1, comprises a Schiff base complex. The bond lengths (Allen et al., 1987) and angles are within the normal ranges and are comparable to the related structure (Kargar et al., 2012;Kargar et al., 2011;Ghaemi, et al., (2011).
The geometry around Cu II is a distorted square-planar which is supported by the N 2 O 2 donor atoms of the coordinated Schiff base ligand. The dihedral angle between the substituted benzene rings is 29.95 (16)°. In the crystal structure the molecules are linked together along the b-axis, forming individual dimers through the intermolecular C-H···O interactions (Table 1, Fig. 2). The crystal structure is further stabilized by the intermolecular π-π interaction [Cg1···Cg1 ii = 3.6131 (17)Å;

Experimental
The title compound was synthesized by adding 3,5-dichloro-salicylaldehyde-2,2-dimethyl-1, 3-propanediamine (2 mmol) to a solution of CuCl 2 . 4H 2 O (2.1 mmol) in ethanol (30 ml). The mixture was refluxed with stirring for half an hour. The resultant solution was filtered. Dark-green single crystals of the title compound suitable for X-ray structure determination were recrystallized from ethanol by slow evaporation of the solvents at room temperature over several days.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq C1 0.5462 (