Second sphere coordination in anion binding: Synthesis, characterization and X-ray structure of cis-diazidobis(ethylenediamine)cobalt(III) mesitylenesulphonate hemihydrate

cis-diazidobis(ethylenediamine)cobalt(III) mesitylenesulphonate hemihydrate, [cis-Co(en)2(N3)2]C9H11SO3·0.5H2O was crystallized from a solution of cis-diazidobis(ethylenediamine) cobalt(III) nitrate and sodium mesitylenesulphonate in aqueous medium in 1:1 molar ratio. Elemental analysis, spectroscopic studies (IR, UV/visible, 1H and 13C NMR) and conductance studies were undertaken for characterizing the complex salt. The compound crystallizes in the triclinic space group P−1 with a=7.15220(10), b=14.5218(3), c=20.6925(5), V=2058.48(7), Z=4. X-ray structure determination revealed an ionic structure consisting of [cis-Co(en)2(N3)2]+ cation, mesitylenesulphonate anion and half water molecule. In the complex cation [cis-Co(en)2(N3)2]+, the cobalt(III) is bonded to six nitrogen atoms, originating from two ethylenediamines, and two azide groups showing an octahedral geometry around cobalt. The crystal lattice is stabilized by electrostatic forces of attraction and hydrogen bonding interactions predominantly N–H…O−, suggesting that [cis-Co(en)2(N3)2]+ is a promising anion receptor for the mesitylenesulphonate ion. This is the first report of a sulphonate salt containing the present cationic cobaltammine.