End-On Oxygen-Bound Sulfur Monoxide Complex of Titanium Oxyfluoride.

The end-on oxygen-bound sulfur monoxide (SO) complex of titanium oxyfluoride [OTiF2(η1-OS)] was prepared via the isomerization of a bidentate sulfur dioxide complex of titanium difluoride [TiF2(O2S)] under UV-vis irradiation in cryogenic matrixes. IR spectroscopy in combination with 18O and 34S isotopic substitutions and density functional theory calculations were employed to identify the product structures and reaction mechanisms. According to the experimental and theoretical results, the OTiF2(η1-OS) complex was characterized to possess a triplet ground state, with the oxygen-bound SO ligand being similar in character to the neutral diatomic SO molecule. It is more stable than the sulfur-bound OTiF2(η1-SO) isomers by about 15.0 kcal/mol but less stable than the TiF2(O2S) precursor by 14.4 kcal/mol at the B3LYP level. The formation of OTiF2(η1-OS) involves cleavage of the S-O bond of TiF2(O2S) with an energy barrier of 25.6 kcal/mol.