Theoretical study of the reaction of CCN radical with H2S

The reaction mechanism of CCN with H2S has been studied by using the method of hybrid density functional B3LYP at the 6-311+G(2d,p) basis set. The transition state of each reaction is verified via the analysis of vibration mode and intrinsic reaction coordinate (IRC). Meanwhile, single-point energy has been calculated at the CCSD(T)/6-311+G(2df,p) and G3B3 level, and the zero-point energy correction has been made to the total energy and reaction energy barrier. For comparison, the reaction of CCN + H2O has also been calculated by the same method. The calculation reveals, for the CCN + H2X (X = S, O), a mechanism of carbyne insertion-dissociation. The most feasible reaction channels are CCN + H2X → H2XCCN (1) → HXC(H)CN (2a) → H + XCHCN (P5) and CCN + H2X → H2XCCN (1) → HXC(H)CN (2a) → HXC(H)CN (2b) → XCH2CN (6) → H + XCHCN (P5), and they both give the dominate products H + XCHCN.