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

In the title Schiff base complex, [Ni(C24H22N2O4)], the NiII atom has a slightly distorted square-planar coordination environment. The dihedral angles between the central benzene ring and the two outer rings are 7.62 (16) and 9.78 (17)°. The crystal structure is stabilized by intermolecular C—H⋯O hydrogen bonds and π–π interactions with a centroid–centroid distance of 3.8218 (19) Å.

In the title Schiff base complex, [Ni(C 24 H 22 N 2 O 4 )], the Ni II atom has a slightly distorted square-planar coordination environment. The dihedral angles between the central benzene ring and the two outer rings are 7.62 (16) and 9.78 (17) . The crystal structure is stabilized by intermolecular C-HÁ Á ÁO hydrogen bonds andinteractions with a centroid-centroid distance of 3.8218 (19) Å .

Comment
Schiff base complexes are one of the most important stereochemical models in transition metal coordination chemistry, with ease of preparation and structural variations (Granovski et al., 1993). Metal derivatives of the Schiff bases have been studied extensively, and nickel(II) and copper(II) complexes play a major role in both synthetic and structurel research (Elmali et al., 2000;Blower et al., 1998).
The molecular structure of the title molecule is illustrated in Fig. 1. The bond lengths (Allen et al., 1987) and angles are within normal ranges. The geometry around the Ni II atom is square-planar being coordinated by the N 2 O 2 donor atoms of the tetradenate Schiff base ligand. The dihedral angle between the mean planes of the central aromatic ring (C9-C14) with the two outer rings (C1-C6 and C18-C23) are 7.62 (16) and 9.78 (17)°, respectively.

Experimental
The title compound was synthesized by adding bis(6-methoxysalicylidene)-4,5-dimethyl phenylenediamine (2 mmol) to a solution of NiCl 2 . 6H 2 O (2 mmol) in ethanol (30 ml). The mixture was refluxed with stirring for 30 min. The resultant red solution was filtered. Dark-red plate-like single crystals of the title compound, suitable for X-ray structure analysis, were obtained by slow evaporation at RT of a solution in ethanol over a period of several days.

Refinement
All the H-atoms were positioned geometrically and included in a riding model approximation: C-H = 0.93 and 0.96 Å for CH and CH 3 H-atoms, respectively, with U iso (H) = k × U eq (C), where k = 1.5 for methyl H-atoms and k = 1.2 for all other H-atoms.  Crystal data [Ni(C 24

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