Unusual reaction paths of SN2 nucleophile substitution reactions CH4 + H− → CH4 + H− and CH4 + F− → CH3F + H−: Quantum chemical calculations

Abstract

Quantum chemical (CCSD(full)/6-311++G(3df,3pd), CCSD(T)(full)/6-311++G(3df,3pd)) and density function theory (B3LYP/6-311++G(3df,3pd)) calculations were performed for the SN2 nucleophile substitution reactions CH4+H−→CH4+H− and CH4+F−→CH3F+H−. The calculated gradient reaction pathways for both reactions have an unusual behavior. An unusual stationary point of index 2 lies on the gradient reaction path. Using Newton trajectories for the reaction path, we can detect VRI point at which the reaction path branches.