ABINITIO DETERMINATION OF SUBSTITUENT CONSTANTS IN A DENSITY FUNCTIONAL THEORY FORMALISM - CALCULATION OF INTRINSIC GROUP ELECTRONEGATIVITY, HARDNESS, AND SOFTNESS

Three intrinsic group properties, the group electronegativity, hardness, and softness, were obtained for 30 organic groups in a nonempirical way starting from the definitions within the framework of density functional theory and applying limited configuration interaction (CISD). The calculated group electronegativities correlated well with most scales introduced for this quantity. The values were compared with the field factor F and with the C-13 1J(CC) (ipso-ortho) coupling constant in monosubstituted benzenes, the most important experimental quantity known to reflect substituent electronegativities. The trends for the group hardnesses and softnesses were interpreted in terms of the hardness (or softness) values for the corresponding central atoms. The correlation with the experimental hardness values for the corresponding radicals was examined and was found to be satisfactory.