First X-ray structure of hexaamminecobalt(III) salt with complex fluoroanion: Synthesis and characterization of [Co(NH3)6]X·SiF6·nH2O, where X = Cl, Br, I and NO3 and crystal structure of [Co(NH3)6]Cl·SiF6·2H2O

Abstract Peach/yellow coloured solids of composition [Co(NH 3 ) 6 ]X·SiF 6 · n H 2 O, where X = Cl, Br, I and NO 3 were obtained directly by reacting [Co(NH 3 ) 6 ]X 3 with Na 2 SiF 6 in 1:1 molar ratio in hot aqueous medium. These hexaamminecobalt(III) complex salts have been characterized by elemental analyses and spectroscopic studies (e.g. UV–vis, IR and 19 F NMR). The single crystals of [Co(NH 3 ) 6 ]Cl·SiF 6 ·2H 2 O suitable for X-ray structure determination were obtained from hot water by slow evaporation at room temperature. Crystal structure determination of this complex salt revealed the presence of discrete ions, i.e. cation [Co(NH 3 ) 6 ] 3+ and mixed anions, Cl − and SiF 6 2− and two lattice water molecules in the solid state. Crystal lattice is stabilized by electrostatic forces of attraction and hydrogen bonding interactions. This is the first X-ray structure determination of a hexaamminecobalt(III) salt with fluoroanion, hexafluorosilicate.