A theoretical study on the potential energy surface of the NCS+NO2 reaction

Abstract In the present study, the reaction mechanism of NCS+NO 2 on the singlet potential energy surface is studied using the MP2/6-311G(d,p) level of theory. It is shown that the pathway (1) NCS + NO 2 ⇌ O ( O ) NNCS → O ( NNC ( S ) O ) → N 2 O + OCS is the major pathway, and the pathways (2) NCS + NO 2 ⇌ O ( O ) NSCN → ONS + OCN and (3) NCS + NO 2 ⇌ cis ‐ cis ‐ ONONCS → NO + SCNO are the minor pathways in the singlet potential energy surface. The major pathway (1), involving the barrierless entrance to the first adduct isomer O(O)NNCS and tight transition states to the products N 2 O and OCS, is in good agreement with the experimentally observed negative temperature dependence of rate constants. The energies of the stationary points are refined using a multi-level method.