Second-sphere coordination in non-spherical anions binding: synthesis, characterization and X-ray structure of cis-diazidobis(ethylenediamine)cobalt(III) 2-chloro,5-nitrobenzene sulphonate monohydrate

Dark red coloured single crystals of [cis-Co(en)(2)(N-3)(2)] C6H3ClNO5S center dot H2O were obtained by slowly mixing the separately dissolved cis-diazidobis(ethylenediamine)cobalt(III) nitrate with sodium 2-chloro,5-nitrobenzenesulphonate in aqueous medium in 1:1 molar ratio. The complex salt was characterized by elemental analyses, spectroscopic studies (IR, UV/visible, H-1 and C-13 NMR) and solubility measurements. The compound crystallizes in the triclinic space group P (1) over bar with a = 7.8128(2), b = 8.3219(2), c = 17.4526(2) angstrom, alpha = 95.224(1), beta = 95.759(1), gamma = 116.636(2)degrees, V = 997.36(5) angstrom(3), Z = 2. Single crystal X-ray structure determination revealed an ionic structure consisting of [cis-Co(en)(2)(N-3)(2)](+), [C6H3ClNO5S](-) and one lattice water molecule. In the complex cation [cis-Co(en)(2)(N-3)(2)](+), the cobalt(III) is bonded to six nitrogen atoms, originating from two ethylenediamine ligands, and two azide groups showing an octahedral geometry around cobalt(III). Supramolecalar hydrogen-bonding networks involving second-sphere coordination like [NHen+center dot center dot center dot X-anion(-)] and NHen+center dot center dot center dot O-water besides electrostatic forces of attraction have been observed to stabilize crystal lattice. This is the first crystal structure of a salt containing 2-chloro,5-nitrobenzenesulphonate anion and cis-diazidobis(ethylenediamine)cobalt(III) cation.