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

Two possible reaction channels of VS+ (3Σ− and 1Γ 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 S-transfer reaction proceeds via two parallel reaction paths (path A and B) yielding two isomer products (VS2+−1 and VS2+-2, respectively), and the exothermicity with endothermic feature of the formation of VS2+ observed experimentally can be attributed to these two 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 (3IM1) indicate the much less efficiency of the reaction, which is in agreement with the experimental observation.