Substituent Effects on Thermochemical Properties of Free Radicals. New Substituent Scales for C-Centered Radicals

In this work, we have analyzed substituent effects on ionization potentials and electron affinities of C-centered radicals in terms of operational atomic contributions. The analysis was based on ionization potential data for 48 C-centered radicals and electron affinity data for 20 C-centered radicals. For both sets of data, the correlation between predicted numbers and experimental data was good ( R = 0.98). Based on these operational atomic parameters, additive substituent constants have also been derived, and equations for prediction of ionization potentials and electron affinities of C-centered radicals are presented.