Substituent effects on the electronic spectra of aromatic hydrocarbons I. A comparison of the localized-orbital and iso-conjugate-hydrocarbon models for interpreting the spectra of amino- and nitrobenzenes

Abstract

Two models are used to analyze the spectra of aniline and nitrobenzene. These are the localized-orbital model, in which there is no delocalization of the electrons between the phenyl group and the substituent, and the iso-conjugate-hydrocarbon model, in which there is complete delocalization. Neither model is very satisfactory with zero-order wave functions and energies. Both give a satisfactory interpretation of the spectra if configuration interaction is taken into account but the localized-orbital model is rather better for calculating energies. The localized-orbital model is also more readily applied to polysubstituted benzenes.