A Theoretical Study on Activation of C-H and C-Cl Bonds in CH3X (X=H, Cl) by Fe2+

The reactions of Fe2+ with CH3X (X=H, Cl) have been studied by density functional theory method detailedly. The results demonstrated that the H abstraction in Eq. 4 can proceed via the lowest activation barrier (Delta G(a)=0.23 kcal/mol) in all feasible pathways. However, the mechanisms of oxidative insertion and the S(N)2 substitution are not competitive because of thermodynamic factors. The electronic structure analysis suggests that the overlap between metal 3d orbital and substrate sigma(*)(c-x) results in the preference of Fe2+ front side attack on the C-X bond. This study is expected to shed light on the nature of the title reactions and provide theoretical clues and foundation for future research.