{1,1′-[2,2-Dimethylpropane-1,3-diylbis(nitrilomethylidyne)]di-2-naphtholato}nickel(II)

In the title Schiff base complex, [Ni(C27H24N2O2)], the NiII atom shows a slightly distorted square-planar geometry. The dihedral angle between the mean planes of the two aromatic rings is 6.16 (6)°. In the crystal, pairs of intermolecular weak C—H⋯O hydrogen bonds link neighboring molecules into a chain along the a axis. The crystal structure is further stabilized by two intermolecular π–π interactions with centroid–centroid distances of 3.7252 (13) and 3.8323 (13) Å.

In the title Schiff base complex, [Ni(C 27 H 24 N 2 O 2 )], the Ni II atom shows a slightly distorted square-planar geometry. The dihedral angle between the mean planes of the two aromatic rings is 6.16 (6) . In the crystal, pairs of intermolecular weak C-HÁ Á ÁO hydrogen bonds link neighboring molecules into a chain along the a axis. The crystal structure is further stabilized by two intermolecularinteractions with centroid-centroid distances of 3.7252 (13) and 3.8323 (13) 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). Metal derivatives of the Schiff bases have been studied extensively, and Ni(II) and Cu(II) complexes play a major role in both synthetic and structural research (Elmali et al., 2000;Blower et al., 1998). The asymmetric unit of the title compound, Fig. 1, comprises one unit of the Schiff base complex. The bond lengths (Allen et al., 1987) and angles are within the normal ranges. The geometry around the Ni(II) atom is a slightly distorted square-planar which is coordinated by the N 2 O 2 donor atoms of the desired potentially tetradenate Schiff base ligand ( Table 1). Pairs of weak intermolecular C-H···O hydrogen bonds (Table 2) link neighboring molecules into a chain along the a-axis. The dihedral angle between the mean planes of the two aromatic rings is 6.16 (6)°. The crystal structure is further stabilized by the intermolecular π-π interactions [Cg1···Cg2 i = 3.7252 (13) and Cg1···Cg2 ii = 3.8323 (13) Å; Cg1 and Cg2 are the centroids of the C4/C5/C6/C7/C8/C9 and C17/C18/C19/C20/C21/C22 benzene rings].
6 H 2 O (2 mmol) in ethanol (30 ml). The mixture was refluxed with stirring for half an hour. The resultant red solution was filtered. Red 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 U eq (C).

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 supplementary materials sup-9