Chain of water hexamers and tetramers hosted in a redox product of a Co(III) metal complex: Syntheses, characterization and single crystal X-ray structure determination of Co(II/III) complexes with sulfur oxo-anions

Abstract

In the present study, four new Co(II/III) metal complexes, [Co(phen)3]S4O6·2H2O (1), [Co(phen)3]S4O6·7H2O (2), [Co(phen)3]2(S4O6)3·6.5H2O (3) and [Co(phen)3]S2O3·9H2O (4), have been synthesized and characterized by elemental analysis, TGA and various spectroscopic techniques. In the case of 1 and 2, an unexpected redox reaction took place and the complexes formed are different in terms of their water of crystallization. The structures of 1–3 have been determined by single crystal X-ray crystallography. Complex salts 1–3 crystallize in the orthorhombic (Pbca), triclinic (P1¯) and monoclinic (P21/c) crystal systems, respectively. Their X-ray crystal structure determination revealed the presence of non-covalent cation-to-anion (C–H⋯Oanion hydrogen bonds), anion-to-cation (anion⋯π interactions) and cation-to-cation (C–H⋯π and π⋯π stacking interactions) interactions. Interestingly, a detailed packing analysis has shown the presence of rare chains of cyclic water hexamers (chair form) and tetramers, stabilized by O–H⋯O and C–H⋯O hydrogen bond interactions in the supramolecular complex [Co(phen)3]S4O6·7H2O (2).