Binding of inorganic oxo-anions to cationic cobaltammine: Synthesis, characterization, X-ray structures determination and DFT calculations of [Co(NH3)6]Cl2(ClO3), [Co(NH3)6]Br2(ClO3) and [Co(NH3)6]Cl2(IO3) · H2O

Single crystals of [Co(NH3)6]Cl2(ClO3) (1), [Co(NH3)6]Br2(ClO3) (2) and [Co(NH3)6]Cl2 (IO3) · H2O (3) suitable for X-ray structure determinations were obtained directly by reacting hexaamminecobalt(III) halide with appropriate metal halates in 1:1 molar ratio in hot aqueous medium. These hexaamminecobalt(III) complexes have been characterized by spectroscopic studies (e.g. UV/Visible and IR). Single crystal X-ray structure determination of title complex salts revealed the presence of discrete ions, i.e., cation [Co(NH3)6]3+ and mixed anions Cl− and View the MathML sourceClO3- or Br− and View the MathML sourceClO3- or Cl− and View the MathML sourceIO3- in the solid state. Crystal lattice is stabilized by electrostatic forces of attraction and hydrogen bonding interactions (N–H⋯O−, N–H⋯Cl− or N–H⋯Br−). The formation of definite salts of composition with halate ions suggests that [Co(NH3)6]3+ may be used as purely inorganic anion binding agent for these weakly coordinating oxo-anions. The DFT calculations have been carried out to calculate molecular volumes of the oxoanions and separation between two successive cation layers.