Theoretical Study on the Gas Phase Reaction of Au + with CS2

T The reaction of Au+(1S,3D)with CS2 has been investigated at the B3LYP and CCSD(T)levels of theory.The identified reaction pathways revealed that the experimentally observed products,AuS+ and AuCS+,can be produced by the insertion of Au+ into C-S bond.The calculated energetics shows that the reactions on singlet surface lead to excited-state products,AuS+(1Σ)+ 1CS and AuCS+(1Σ)+ 1S,and have notable energy barriers,whereas the reactions on triplet surface producing the ground state products of AuS+(3Σ)+ 1CS and AuCS+(1Σ)+ 3S are energetically much more favorable.This result suggests that the minor formations of AuS+ and AuCS+ observed in the previous experiment under room-temperature condition should result from the reactions of excited-state Au+(3D)with CS2.Further,the possibility for singlet-triplet surface crossing was also discussed by approximately determining the crossing region.