A sulfur monoxide complex of platinum fluoride with a positively charged ligand

Abstract

A sulfur monoxide complex of platinum fluoride in the form of PtF₂(η¹-SO) was generated via the isomerization of a molecular complex Pt(SOF₂) in cryogenic matrixes under UV-vis irradiation. The infrared absorptions observed at 1205.4, 619.8 and 594.9 cm⁻¹ are assigned to the S–O, antisymmetric and symmetric F–Pt–F stretching vibrations of the PtF₂(η¹-SO) complex, which possesses nonplanar C_s symmetry with a singlet ground state according to density functional theory calculations. The experimental vibrational frequency and computed distance (1.449 Å) of the SO ligand indicate that the SO ligand features a positively charged character, which is further confirmed by natural bond orbital analysis and Mayer bond order. Such character is completely different from that for early transition metal–SO complexes and dioxygen complexes of platinum. Formation of the PtF₂(η¹-SO) complex was found to occur via the consecutive transfer of the two fluorine atoms from SOF₂ to Pt in the sulfur bound Pt(SOF₂) complex, which involves a series of intermediates on the basis of the mechanism study at the B3LYP level. Although the whole process is hindered by the large energy barrier encountered during the transfer of the first fluorine atom, UV-vis irradiation can provide sufficient energy to surmount this barrier and facilitates the formation of the nonplanar PtF₂(η¹-SO) complex stabilized in matrix.