Theoretical Study of the Acetonitrile Reaction with the Methine Radical

Results of a theoretical study of the methine radical (CH) with acetonitrile (CH3CN), which is a potentially important step in formation of heterocyclic nitrogen-containing molecules in the interstellar space and planetary atmospheres, are presented. A profile of the potential energy surface is constructed, which describes the mechanism of formation of both linear and cyclic products. The geometry, frequency of oscillations, and relative energy of the resultant structures are determined with the use of the explicitly correlated coupled cluster method and the density functional theory CCSD(T)-F12/cc-pVTZ-f12//omega B97xd/cc- pVTZ. Within the framework of the Rice-Ramsperger-Kassel-Marcus theory, rate constants and branching ratios of reaction products are calculated under the conditions of deep space corresponding to the limit of zero pressure for various impact energies. It is found that the branching ratios of reaction products depend on the initial adducts of the reaction.