Theoretical Survey of the Potential Energy Surfaces Associated with the N⁺(³P,D) + C₂H₄Reactions in the Gas Phase

Abstract

The potential energy surfaces (PESs) associated with the reactions between ethylene and N+(3P,1D) ions have been investigated through the use of high-level G2(MP2) ab initio calculations. Although the N+(3P) + C2H4 entrance channel lies 46.7 kcal mol-1 below the N+(1D) + C2H4, 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+ + C2H4 reactions cannot be discarded. According to our survey, the product distribution in both N+(3P) + C2H4 and N+(1D) + C2H4 reactions should be quite different. While for the triplets the CNH+, HCNH+, HCCH2 +, and HCCH+ product ions should be observed, in agreement with the available experimental information, for the singlets the formation of CH3 + should be the dominant process.

Two‐ and three‐state conical intersections in the electron capture dissociation of disulfides: The importance of multireference calculations

“…They are rationalized with the two‐state 25–27 or multistate (MS) 28 reactivity concepts, where the crossing of two or more spin states produces the spin flipping necessary to reach the final products and which can provide lower energy reaction paths for otherwise too high‐activation channels. This scenario is usually found in organometallic chemistry 29–33, because the partially occupied d shell of transition metals facilitates the appearance of different spin states of close energy, but it is applicable to many spin‐forbidden reactions 34–36.…”