Theoretical Survey of the Potential Energy Surfaces Associated with the N+(3P,D) + C2H4 Reactions in the Gas Phase

Abstract

The potential energy surfaces (PESs) associated with the reactions between ethylene and N + ( 3 P, 1 D) ions have been investigated through the use of high-level G2(MP2) ab initio calculations. Although the N + ( 3 P) + C 2 H 4 entrance channel lies 46.7 kcal mol - 1 below the N + ( 1 D) + C 2 H 4 , most of the singlet-state cations are more stable than their triplet-state counterparts because, in general, the bonds in the former are stronger than those in the latter, favoring the crossover between both PESs. Several minimum energy crossing points between both hypersurfaces have been located, and the corresponding spin-orbit couplings indicate that spin-forbidden processes in N + + C 2 H 4 reactions cannot be discarded. According to our survey, the product distribution in both N - ( 3 P) + C 2 H 4 and N + ( 1 D) + C 2 H 4 reactions should be quite different. While for the triplets the CNH + , HCNH, HCCH 2 + , and HCCH + product ions should be observed, in agreement with the available experimental information, for the singlets the formation of CH 3 + should be the dominant process.