Cationic cobalt(III) complex as anion receptor for biologically important anion: Synthesis, characterization and X-ray structure of [Co(phen)3](C7H4NSO3)3.8.5H2O where C7H4NSO3 = saccharinate ion

In an effort to explore [Co(phen)3]3+ complex cation as anion receptor for biologically important saccharinate ion, yellow coloured single crystals of [Co(phen)3](C7H4NSO3)3.8.5H2O were obtained by slow evaporation of solution, obtained by mixing the separately dissolved, tris(1,10-phenanthroline)cobalt(III)chloride and sodium saccharinate in aqueous medium in 1:3 molar ratio. The newly synthesized complex salt was characterized by elemental analysis, TGA, conductance, solubility product measurements and spectroscopic studies (IR, UV/Visible, 1H and 13C NMR). Single crystal X-ray structure determination of [Co(phen)3](C7H4NSO3)3.8.5H2O revealed that compound crystallizes in the triclinic crystal system with space group P1¯ where a = 12.3795(4), b = 12.7598(4), c = 19.0414(5) Å, α = 71.544(2), β = 76.457(2), γ = 9 77.213(2)°, V = 2738.19(14) Å3, Z = 2. The crystal lattice is stabilized by hydrogen bonding interactions of type OH⋯O and CH⋯O (through second sphere coordination) besides the electrostatic forces of attraction. The solubility product and conductance measurements indicated that the affinity of cationic tris(1,10-phenanthroline) cobalt (III), [Co(phen)3]3+ is greater for saccharinate ion than for chloride ion in aqueous medium. The structural studies suggest that [Co(phen)3]3+ is a potential anion receptor for the saccharinate ion.