{6,6′-Diethoxy-2,2′-[4,5-dimethyl-o-phenylenebis(nitrilomethylidyne)]diphenolato}copper(II)

In the title complex, [Cu(C26H26N2O4)], the CuII ion lies on a crystallographic twofold rotation axis and is coordinated in a slightly distorted square-planar environment. The dihedral angle between the central benzene ring and each of the two symmetry-related outer benzene rings is 5.1 (2)°. The crystal structure is stabilized by intermolecular π–π interactions with centroid–centroid distances in the range 3.466 (2)–3.6431 (16) Å.

In the title complex, [Cu(C 26 H 26 N 2 O 4 )], the Cu II ion lies on a crystallographic twofold rotation axis and is coordinated in a slightly distorted square-planar environment. The dihedral angle between the central benzene ring and each of the two symmetry-related outer benzene rings is 5.1 (2) . The crystal structure is stabilized by intermolecularinteractions with centroid-centroid distances in the range 3.466 (2)-3.6431 (16) Å .

Experimental
The title compound was synthesized by adding bis(3-ethoxysalicylidene)-4,5-dimethyl phenylenediamine (2 mmol) to a solution of CuCl 2 .4H 2 O (2 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.

Refinement
All hydrogen atoms were positioned geometrically with C-H = 0.93-0.97 Å and included in a riding model approximation with U iso (H) = 1.2 or 1.5 U eq (C). A rotating group model was applied to the methyl groups.  Crystal data [Cu(C 26

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