Theoretical study on the reaction of VS+ (3Σ-, 1Γ) with COS in the gas phase

Two possible reaction channels of VS+ ((3)Sigma(-) and (1)Gamma states) with COS in the gas phase have been studied by using density functional theory at B3LYP/DZVP level: the O/S exchange reaction (VS+COS -> VO+CS2) and the S-transfer reaction (VS+COS -> VS2+CO). The different mechanisms on the triplet and singlet surfaces have been identified. It is found that the 2 S-transfer reaction proceeds via two parallel reaction paths (path A and B) yielding two isomer products (VS2+-1 and VS2+-2, 2 2 respectively), and the exothermicity with endothermic feature of the formation of VS+ observed experimentally can be attributed to these two 2 reaction paths with the calculation reaction heats of -20.5 and 70.5 kJ/mol, respectively, on the ground triplet surface. The larger barrier (103.6 kJ/mol) of the O/S exchange reaction and the smaller probability of the formation of its preceding intermediate ((3)IM1) indicate the much less efficiency of the reaction, which is in agreement with the experimental observation. (c) 2004 Published by Elsevier B.V.