Computational Study on Reaction Mechanisms and Kinetics of RNCN (R = H, F, Cl, Br, CH3) Radicals with NO

We carried out a computational study of radical reactions of RNCN (R = H, F, Cl, Br, CH3) + NO to investigate how the substitution can influence their corresponding energy barriers and rate coefficients. The preferable reactive sites of RNCN radicals with various substituents are calculated by employing the Fukui functions and hard-and-soft acid-and-base theory, which were generally proved to be successful in the prediction and interpretation of regioselectivity in various types of electrophilic and nucleophilic reactions. Our calculated results dearly show that if the substituted RNCN radical has electron-donating substituent (for R = CH3), its corresponding barrier heights for transition states will be substantially decreased. The possible explanations of the observed increase and/or decrease in the energy barriers for the varied substituted RNCN radicals are also analyzed in this article.