The reaction mechanism of the reaction N₂O (¹∑^＋)＋CO (¹∑^＋) → N₂ (¹∑^＋_g)＋CO₂ (¹∑^＋_g) catalyzed by alkaline-earth metal cations ²Sr^＋ and ²Ba^＋ have been investigated by using the UB3LYP density functional theory (DFT, UB3LYP) with the relativistic effective core potential (RECP) of basis sets (SDD) for ²Sr^＋, ²Ba^＋ and the 6-311＋G(2d) basis set for C, N and O on doublet energy surfaces. The geometries for reactants, the transition states and the products are completely optimized. All the transition states are verified by the vibrational analysis and the internal reaction coordinate (IRC) calculations. The results show both main reactions process in a two-step manner to products. NBO analysis has been used to discuss the structure of reactant-complexes, our calculated results for the title reactions are in close agreement with experimental observations.

Key words: ²Sr^＋, ²Ba^＋, N₂O＋CO, reaction mechanism, density functional theory (DFT)