Theoretical study on the reaction of the ground state ~1Σ~+ of ScS~+ with oxygen-transfer reagent: ScS~+ + H_2O → ScO~+ + H_2S in the gas phase

摘要

The reaction mechanism of the ground state ~1Σ+ of ScS~+ with oxygen-transfer reagent: ScS~+ + H_2O → ScO~+ + H_2S in the gas phase has been proposed and investigated by ab initio methods with 6-31G~(**) basis set for non-metal atoms and the ECPs of Lan12dz for Sc. The reaction is proceeding via two steps with seven stationary points (reactants, three intermediate complexes: (I), (II) and (III), two transition states: TS1 and TS2, and products) on the reaction potential surface which involved two 1,3-hydrogen-shift reactions from oxygen atom to sulfur atom via a four-center transition state, respectively. The activation energies of the two steps are 25.3 and 30.2 kcal mol~(-1), respectively, at MP4 (SDTQ)/6-31G~(**)//MP2/6-31G~(**) level plus zero-point energy, which indicates that the second reaction step is the rate-determining step and the theoretical rate constants based on the transition state theory (TST) with Wigner and Eckart tunneling correction are 2.45 and 42.02 (in 10~(-10) s~(-1)), respectively, for the forward reaction and 0.003 and 0.48 (in 10~(-10) s~(-1)) for the reverse reaction.