Methane Activation by Titanium Monoxide Molecules:A Matrix Isolation Infrared Spectroscopic and Theoretical Study

摘要

Reactions of titanium monoxides with methane have been investigated using matrix isolation infrared spectroscopy and theoretical calculations.Titanium derivatives of several simple oxyhydrocarbons have been prepared and identified.The titanium monoxide molecules prepared by laser evaporation of bulk TiO_2 target reacted with methane to form the TiO(CH_4)complex in solid argon,which was predicted to have C_(3v)symmetry with the oxygen atom coordinated to one hydrogen atom of the methane molecule.The complex rearranged to the CH_3Ti(O)H titano-acetaldehyde molecule upon visible (lambda > 500 nm)irradiation.The titano-acetaldehyde molecule sustained further photochemical rearrangement to the CH_2-Ti(H)OH titano-vinyl alcohol molecule,which was characterized to be a simple carbene complex involving agostic bonding.The CH_2Ti(H)OH molecule reacted with a second methane to form the (CH_3)_2Ti(H)OH titano-isopropyl alcohol molecule spontaneously on annealing.The (CH_3)_2Ti(H)OH molecule also can be produced via UV photon-induced rearrangement of the CH_3Ti(O)H(CH_4)complex.