Theoretical study on the reaction of Mn+ (7S and 5S states) with COS

The reaction mechanism of the Mn+ (7S and 5S states) with COS has been studied by means of density functional method (B3LYP). The overall energetics has been refined at the CCSD (T) level. The calculated results indicate that both the C-S and C-O bond activations proceed via an insertion-elimination mechanism. The C-S bond activation is found to be much more favorable than the C-O bond activation. Intersystem crossing between the septuplet and quintet surfaces may occur along both the C-O and C-S bond activation branches. The calculated barriers of spin-forbidden reaction Mn+ (7S) + COS → MnS+ (5Π) + CO and spin-allowed reaction Mn+ (7S) + COS → MnS+ (7Π) + CO are 17.6 and 43.8 kcal/mol, respectively, which are in good agreement with the values assigned in the experiment.