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

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 S(N)2 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. (C) 2013 Elsevier B. V. All rights reserved.