A theoretical study on the gas phase reaction of Pd+ and Pt+ with CS2

The reactions of Pd+ and Pt+ with CS2 have been investigated at B3LYP, CCSD(T) and QCISD(T) levels of theory. Both Pd+ and Pt+ are found to be able to activate the C-S bond in CS2 and produce the products PdS+ and PtS+ through insertion-elimination mechanism. For both Pd+ and Pt+ the spin-forbidden reaction 2M+ + CS2 → 4MS+ + CS is found to be energetically more favorable than the spin-allowed reaction 2M+ + CS2 → 2MS+ + CS. According to the identified reaction mechanisms and PESs, the doublet-quartet surface-crossing is presumed to occur at the exit channel of the reaction. The reactions of Ni+, Pd+ and Pt+ with CS2 are systematically compared in reaction mechanism and potential energy surface. Although all these reactions exhibit obvious endothermic feature, comparisons of these reactions indicate that the reaction of Pt+ with CS2 is energetically much more favorable. The calculated results well rationalize the experimental observations.