Structure of a Hydrated Sulfonatotitanyl(IV) Complex in Aqueous Solution and the Dimethylsulfoxide Solvated Titanyl(IV) Ion in Solution and Solid State

The coordination chemistry of oxotitanium(IV) or titanyl(IV), TiO²⁺, has been studied in solution by X-ray methods. The titanyl(IV) ion hydrolyzes easily in aqueous systems to solid titanium dioxide as long as it is not stabilized through complexation. In this study the structures of the hydrated bissulfatotitanyl(IV) complex and the dimethylsulfoxide (DMSO) solvated titanyl(IV) ions have been determined. In isolated monomeric titanyl complexes titanium(IV) binds strongly to a doubly bound oxo group at ca. 1.64 Å, to four ligands in the equatorial plane almost perpendicular to the Ti=O bond at ca. 2.02 Å, and there is one weakly bound ligand, trans to the Ti=O bond, at ca. 2.22 Å, for oxygen donor ligands; the O=Ti–O_eq bond angles are 95°–100°. The structure of the DMSO solvated titanyl(IV) ion in the solid state is maintained in DMSO solution.