A SEMI-EMPIRICAL CALCULATION OF POTENTIAL SURFACE FOR CH3 + CH2 = CH2 REACTION

A model for the reaction CH3.+CH2=CH2 is studied including the hybridization change of the reaction center. The interaction energy is devided into two parts. The first is a stabilization energy - the contribution due to the π-electron delocalization (including the hybridization effects). It is computed by the PPP method. The second part is an exchange repulsion due to all valence electrons of the three carbon atoms. Correlation corrections are considered. A potential energy surface is constructed, giving a saddle point value close to the experimental activation energy. A discussion is given of the approximations involved. The method suggested is a generalization of the reactivity indices method of the theory of chemical reactivity. It can be regarded as a justification of this more empirical approach. © 1969 Springer-Verlag.