Second sphere coordination in anion binding: Synthesis, spectroscopic and X-ray structural study of [Co(phen)3]2[Hg(SCN)4]3·3H2O

The complex salt [Co(phen)3]2[Hg(SCN)4]3·3H2O was synthesized by mixing the separately dissolved tris(1,10-phenanthroline)cobalt(III) chloride, mercury(II) chloride and ammonium thiocyanate in aqueous medium in 2:3:12 molar ratio. The newly synthesized complex salt was characterized by elemental analyses, spectroscopic studies (IR, 1H, 13C and 59Co NMR). Single-crystal X-ray structure determination of [Co(phen)3]2[Hg(SCN)4]3·3H2O revealed that the complex salt crystallizes in the monoclinic crystal system with space group P21/n where a = 12.0150(4), b = 20.1916(5), c = 36.1151(9) Å, β = 94.408(2)°, V = 8735.7(4) Å3, Z = 4. The asymmetric unit consists of two complex cations, three anions and three lattice water molecules. Crystal lattice is stabilized by hydrogen bonding interactions of type C–H…O, C–H…N through second sphere coordination and O–H…O interactions besides the electrostatic forces of attraction. The structural studies suggest that [Co(phen)3]3+ is a potential anion receptor for the [Hg(SCN)4]2− ion.