{4,4′,6,6′-Tetrabromo-2,2′-[2,2-dimethylpropane-1,3-diylbis(nitrilomethanylylidene)]diphenolato}nickel(II)

The asymmetric unit of the title compound, [Ni(C19H16Br4N2O2)], comprises half of a Schiff base complex. The geometry around the NiII atom, located on a twofold rotation axis, is distorted square-planar, which is supported by the N2O2 donor atoms of the coordinated ligand. The dihedral angle between the substituted benzene rings is 23.19 (17)°. In the crystal, a short intermolecular Br⋯Br [3.6475 (7) Å] interaction is present.

The asymmetric unit of the title compound, [Ni(C 19 H 16 Br 4 N 2 O 2 )], comprises half of a Schiff base complex. The geometry around the Ni II atom, located on a twofold rotation axis, is distorted square-planar, which is supported by the N 2 O 2 donor atoms of the coordinated ligand. The dihedral angle between the substituted benzene rings is 23.19 (17) . In the crystal, a short intermolecular BrÁ Á ÁBr [3.6475 (7) Å ] interaction is present.

Experimental
Crystal data [Ni(C 19 H 16 (Granovski et al., 1993;Blower et al., (1998). In continuation of our work on the crystal structures of Schiff base metal complexes (Kargar et al., 2012;Ghaemi et al., 2011), we report herein on the crystal structure of the title compound.
The asymmetric unit of the title compound, Fig. 1, comprises half of a Schiff base complex. The nickel(II) atom and the central bridging C atom, C9, are located on a 2-fold rotation axis. The bond lengths (Allen et al., 1987) and angles are within normal ranges and are comparable to those reported for related structures (Kargar et al., 2012;Ghaemi et al., 2011).
The geometry around Ni 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 23.19 (17)°.

Experimental
The title compound was synthesized by adding 3,5-dibromo-salicylaldehyde-2,2-dimethyl-1, 3-propanediamine (2 mmol) to a solution of NiCl 2 . 6H 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.

Refinement
The H-atoms were included in calculated positions and treated as riding atoms: C-H = 0.93, 0.96 and 0.97 Å for CH, CH 3 and CH 2 H-atoms, respectively, with U iso (H) = k x U eq (C), where k = 1.5 for CH 3 H-atoms, and = 1.2 for other Hatoms.    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