Second-sphere coordination in hexaamminecobalt(III) salt with organic sulphonate anion: Synthesis, characterisation and X-ray crystal structure of [Co(NH3)6](CH3SO3)3

Reaction of hexaamminecobalt(III) chloride with the silver salt of methanesulphonic acid in aqueous medium (1:3 molar ratio) forms hexaamminecobalt(III) methanesulphonate, [Co(NH3)6](CH3SO3)3, in high yield. This cobalt(III) complex has been characterized by spectroscopic techniques (UV/visible, IR and NMR) and its solubility product determined. The X-ray crystal structure shows that the [Co(NH3)6]3+ cations interact at the second sphere by sharing edges with the CH3SO3- anions, via N–H ⋯ O hydrogen bonds. The structure is related to that of [Co(NH3)6]Cl(CH3SO3)2, but is modified to accommodate additional CH3SO3- anions in place of Cl−.