Bis{2,4-dibromo-6-[(2-phenylethyl)iminomethyl]phenolato-κ2 N,O}cobalt(II)

In the title complex, [Co(C15H12Br2NO)2], the CoII atom is four-coordinated by two N,O-bidentate chelate Schiff base ligands, displaying a flattened tetrahedral coordination environment. The CoII atom occupies a special position on a twofold rotation axis. In the crystal, molecules are linked via weak C—H⋯Br interactions.

This work was supported by the school scientific research fund of Henan University of Technology.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BR2176).

Comment
Cobalt is an important life-required element. For example, vitamin B12, also called cobalamin, is a water soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood (Randaccio et al., 2010). In addition, the Schiff base metal complexes generally possess antitumour activities (Ren et al., 2002) and antimicrobial activities (Panneerselvam et al., 2005). By taking the biological importance of element cobalt into account, we synthesized the title complex with the bidentate N,O-donor Schiff base ligands (Scheme I).
In the title compound, the Co II atom occupies a special position on a twofold rotation axis to form a distorted tetrahedral coordination sphere. Cobalt(II) atom is four-coordinated by two imino N atoms and two phenolic O atoms from two bidentate Schiff-base ligands derived from the condensation of 3,5-dibromosalicylaldehyde and 2-phenylethylamine ( Fig. 1). All bond lengths are within normal ranges (Allen et al., 1987). The C7═N1 bond length of 1.284 (4) Å is within the range of 1.256 (14)-1.310 (15) Å observed in the analogous tetrahedral Co(II) species (Chen et al., 2010;. The Co-O and Co-N bond distances of 1.916 (2) and 1.986 (3) Å are also similar to those of 1.935 (2) and 2.006 (3) Å previously reported in the related cobalt(II) complex of a Schiff base ligand derived from the condensation of 3,5-dibromosalicylaldehyde and benzylamine (Jiang et al., 2008).
In the crystal structure, the molecules are linked via weak C-H···Br interactions (Fig.2).
Experimental 3,5-Dibromosalicylaldehyde (560 mg, 2 mmol) and 2-phenylethylamine (242 mg, 2 mmol) were dissolved in a methanol solution (25 mL).The mixture was stirred at room temperature for 1 h to give an orange solution, which was added to a methanol solution (15 mL) of Co(NO 3 ) 2 .6H 2 O (280 mg, 1 mmol). The mixture was stirred for another 25 min at room temperature to give a red solution and then filtered. The filtrate was kept in air for 7 days, forming red blocky crystals. The crystals were isolated and dried in a vacuum desiccator containing anhydrous CaCl 2 , in about 64% yield.  1614,1502,1433,1410,1310,1210,1152,865,749,703,486,437.

Refinement
All the H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C-H distances of 0.93 and 0.97 Å, and with U iso (H) = 1.2U eq (carrier).
supplementary materials sup-2 Figures Fig. 1. The structure of the title compound, with the atom numbering scheme of the unique atoms (30% probability ellipsoids).

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.