Second-sphere coordination complexes via hydrogen bonding: Synthesis, characterization of [Co(NH3)6](XO3)3·nH2O (X=Br, I) and single crystal X-ray structure determination of [Co(NH3)6](BrO3)3·0.5H2O

Single crystals of [Co(NH3)6](BrO3)3·0.5H2O and peach coloured precipitate of [Co(NH3)6](IO3)3·3H2O were obtained by reacting hexaamminecobalt(III) chloride with appropriate silver halate in 1:3 molar ratio in hot aqueous medium. These hexaamminecobalt(III) complexes have been characterized by spectroscopic studies (e.g. UV–vis and IR). Single crystal X-ray structure determination of title complex salt revealed the presence of discrete ions, i.e. cation [Co(NH3)6]3+, three anions, BrO 3 − and half water molecule in the solid state. Crystal lattice is stabilized by electrostatic forces of attractions and hydrogen bonding interactions (N–H⋯O−, O–H⋯O−). The formation of salts of definite composition with halate ions and solubility product data suggest that purely inorganic hexaamminecobalt(III) cation may be used as an anion receptor for these weakly coordinating inorganic oxo-anions.