cis-Bromido(methylamine)bis(propane-1,3-diamine)cobalt(III) dibromide

In the title compound, [CoBr(CH5N)(C3H10N2)2]Br2, the cobaltIII ion has a distorted octahedral coordination environment and is surrounded by four N atoms in the equatorial plane, with an additional N atom and the Br atom occupying the axial positions. In the crystal, the complex cation and the two counter anions are linked via N—H⋯Br and C—H⋯Br hydrogen bonds, forming a three-dimensional network.

In the title compound, [CoBr(CH 5 N)(C 3 H 10 N 2 ) 2 ]Br 2 , the cobalt III ion has a distorted octahedral coordination environment and is surrounded by four N atoms in the equatorial plane, with an additional N atom and the Br atom occupying the axial positions. In the crystal, the complex cation and the two counter anions are linked via N-HÁ Á ÁBr and C-HÁ Á ÁBr hydrogen bonds, forming a three-dimensional network.
Complexes of cobalt are useful for nutritional supplementation to provide cobalt in a form which effectively increases the bioavailability, for instance, vitamin B12 by microorganisms present in the gut. In addition, cobalt(III) complexes are known for electron transfer and ligand substitution reactions, which find applications in chemical and biological systems.
Against this background and to ascertain the molecular conformation, the structure determination of the title compound has been carried out.
The present research is the design and synthesis of cobalt(III) complexes with an objective to understand the structurereactivity correlation. Substituting an amino ligand for the MeNH 2 moiety can yield complexes of similar structure, but with differing electron transfer rates (Anbalagan, 2011;Anbalagan et al., 2011).
X-ray analysis confirms the molecular structure and atom connectivity as illustrated in Fig (Lee et al., 2007;Ramesh et al., 2008;Anbalagan et al., 2009;Ravichandran et al.,2009). One of the six membered rings in the molecule adopts a chair conformation. The crystal packing is stabilized by C-H···Br and N-H···Br interactions along the a axis as shown in Fig.2.

Experimental
Crystalline trans-[Co III (tn) 2 Br 2 ]Br (2g) was made into a paste using 3-4 drops of water. To the solid mass, about 4 ml of 0.12 M methyl amine (MeNH 2 ) was dropped for 30 min and mixed well. The grinding of a dull green paste was continued to obtain a red mass and the reaction mixture was set aside until no further change was observed. Then the product was allowed to stand overnight and the solid was washed with ethanol. The final product was dissolved in 5-10 ml of water pre-heated to 70°C and allowed to crystallize in hot acidified water(few drops of hot conc. HCl and 2 ml of water and cooled). Finally, microcrystalline pink color crystals were retrieved (yield 0.87 g), filtered, washed with ethanol and dried over vacuum. X-ray quality crystals were obtained by recrystallization from hot acidified distilled water.

Figure 1
View of the title molecule with the atom labelling scheme. The displacement ellipsoids are drawn at the 30% probability level while the H atoms are shown as small spheres of arbitrary radii.  The molecular packing viewed down the a axis. Dashed lines shows the intermolecular N-H···Br and C-H···Br hydrogen bonds. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.50 e Å −3 Δρ min = −2.69 e Å −3 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.