AB INITIO CALCULATIONS ON A TYPICAL SN2REACTION - ELECTRONIC STRUCTURE OF METHYL FLUORIDE AND OF TRANSITION STATE (FCH3F)-

The electronic structure of the initial and transition states of the substitution reaction F-+CH3F →FCH3+F- have been calculated by the SCF molecular orbital method in the Gaussian approximation. It is found that the energy of the transition state is lower than the sum of the energies of the separated systems CH3F and C-. However, this negative contribution to the activation energy is balanced by the variation of solvatation energies. © 1969 Springer-Verlag.