Matrix-Isolation Infrared and Theoretical Study of the Reaction of VCl4 with CH3OH

Abstract

The matrix isolation technique, combined with infrared spectroscopy and theoretical calculations, has been used to investigate VCl4, as well as its reactions with CH3OH and its isotopomers. The infrared spectrum of VCl4 in solid argon showed an intense doublet at 474 and 501 cm-1, which is indicative of a splitting of the triply degenerate stretching mode in Td symmetry due to Jahn−Teller distortion. Density functional theory (DFT) calculations (UB3LYP/6-311++g(d,2p)) reproduced this splitting very well. The calculated structure had four equal V−Cl bonds, but with two Cl−V−Cl angles equal to 110.8° and two angles equal to 106.9°. Using twin-jet deposition, the initial intermediate in the reaction of VCl4 with CH3OH was identified as a 1:1 molecular complex, characterized by perturbations to the V−Cl, C−O, and O−H stretching modes. This complex was destroyed by near-UV irradiation, producing the novel Cl3VOCH3 species and cage-paired HCl. Merged-jet co-deposition of CH3OH and VCl4, with a room-temperature reaction zone, led to almost-complete conversion to Cl3VOCH3. This species was identified by use of isotopic labeling, the observation of HCl as an additional reaction product, and by comparison to DFT calculations. In addition, a large yield of CH3Cl was observed.