Stabilization of tetrameric metavanadate ion by tris(1,10-phenanthroline)cobalt(III): synthesis, spectroscopic, and X-ray structural study of [Co(phen)3]3(V4O12)2Cl 27H2O

A new complex salt, [Co(phen)3]3(V4O12)2Cl•27H2O (phen = 1,10-phenanthroline and [V4O12]4- = tetrameric metavanadate, dodecaoxotetravanadate ion), was synthesized by the reaction of appropriate salts in aq. medium. The complex salt was characterized by elemental analyses, TGA, cyclic voltammetry, FTIR, and UV-visible spectroscopies, soly. product and conductance measurements. Single crystal x-ray structure detn. revealed ionic structure consisting of three complex cations, [Co(phen)3]3+, two [V4O12]4- anions, one chloride and 27 lattice water mols. Detailed structural and spectroscopic analyses of [Co(phen)3]3(V4O12)2Cl•27H2O showed that the large anion is stabilized by the large cationic metal complex as there is preferred shape compatibility that leads to a large no. of lattice-stabilizing noncovalent interactions.