Estimation of Substituent Group Electronic Influence from Molecular Connectivity Delta Values

Abstract

AbstractAn estimation of the relative electronegativities of atoms in their valence state is presented, based upon counts of valence and sigma electrons other than those bonding with hydrogen. This Kier/Hall valence state electronegativity is linearly related to the Mulliken‐Jaffe' electronegativity. This estimation is extended to include group electronegativities. Groups, treated as benzene ring substituents, are evaluated in terms of their electronic influence on a benzene ring. This influence is partitioned into electronegativity equalization effects through sigma and pi orbital interactions plus lone pair orbital pressure on the ring pi system. A simple summation of these three influences, calculated very easily from structure, is found to be well correlated with the Hammett values for 25 common substituents for both para and meta position values. The present treatment deals with first row elements.