Preparation of Group 3 Metal Sulfur Monoxide Complexes via Oxidation of Metal Atoms using SOF₂ in Cryogenic Matrixes

Abstract

Side-on sulfur monoxide complexes of scandium, yttrium, and lanthanum difluorides [MF 2 (η 2 -SO)] were prepared via oxidation of metal atoms by SOF 2 in cryogenic matrixes. The structures of these SO complexes are determined by characteristic infrared absorptions as well as isotopic frequency ratios, and the assignments are further supported by density functional theory calculations. A doublet ground state with nonplanar C s symmetry was established for all the complexes with side-on SO ligands. The SÀ O bond lengths as well as the SÀ O stretching vibrational frequencies approach those of SO À , suggesting that the group 3 metal MF 2 (η 2 -SO) complexes can be considered as (MF 2 ) + (SO) À . Consistent with this notion, the interaction between MF 2 and SO is mainly ionic with SO negatively charged by about À 0.60 e, and the unpaired electron is located in the SO 3π orbital that is antibonding in character. It is highly exothermic to form MF 2 (η 2 -SO) mediated by a single fluorine transfer MF(SOF) intermediate from the reactions of SOF 2 and metal atoms. The absence of group 3 metal sulfur monoxide complexes using SO 2 F 2 as a precursor is because the resulting complexes would require a metal center with the oxidation state higher than III.