The reaction of Cu⁺ and Zn⁺ with CS₂, was selected as a representative system of reactions of first-row transition metal ions with CS₂. The reaction mechanism between first-row transition metal ions in ground state and excited state and CS₂ has been studied using the density functional theory (DFT) at UB3LYP/6-311+G^* level. The geometries for reactants, the transition states and the products were completely optimized. All the transition states were verified by the vibrational analysis and the intrinsic reaction coordinate calculations. For each stationary point, single-point UCCSD(T) energy calculations were carried out. A potential energy curve-crossing diagram was investigated for state correlation between singlet ¹IM1 and triplet ³IM2 in the reactin of Cu⁺ with CS₂. The result showed that the reaction mechanism between first-row transition metal ions and CS₂ was an insertion-elimination mechanism. The main reaction path channel was detected in the reaction of metal ions in ground state and excited state with CS₂.

Key words: transition-metal ion, carbon bisulfide, reaction mechanism, density functional theory