Reaction mechanism of cyanoethynyl radical (C3N) with ethylene (C2H4) to form C5H3N and H: a theoretical investigation

The reaction mechanisms of cyanoethynyl radical (C3N) with ethylene (C2H4) to form C5H3N and H were investigated using density functional theory and a high-level ab initio method such as the coupled-cluster singles and doubles including a perturbative estimate of triples (CCSD(T)). The reaction pathways can be categorized into three types. The first pathway includes only chain intermediates (IMs). The second pathway includes ring IMs except for pyridine-like structures. The final pathway includes the pyridine-like structures. On the basis of the calculated results, the most favorable reaction pathway is the first type; the H elimination takes place from the initial chain adduct of C3N with C2H4. Because C3N and butadinyl (C4H) radical are isoelectronic, the most favorable reaction pathway and barrier energy of the reaction of C3N with C2H4 are almost identical to those of the reaction of C4H with C2H4.