Theoretical study on the reaction of Nb+ with COS in the gas phase

The reaction mechanism of Nb+ (5D, 3P, 1S) with COS has been investigated in detail by means of density functional method (B3LYP). To obtain an accurate evaluation of the activation barrier and reaction energy, the coupled cluster single-point calculations (CCSD(T)) using the B3LYP structures are performed. The calculated results indicate that the CS bond activation has two different mechanisms, one is an insertion-elimination mechanism, the other is directly abstraction S atom mechanism. The CO bond activation proceeds via an insertion-elimination mechanism. The CS bond activation is found to be energetically much more favorable than the CO bond activation. The Nb+(5D)+ COS(1Σ) → NbS+(3Σ−) + CO(1Σ) and Nb+(5D) + COS(1Σ) → NbO+(3Σ−) + CS(1Σ) are found to proceed through a quintet-triplet surface and the crossing regions were approximately determined. All of the results have been compared with existing experimental and theoretical data.