Intramolecular Charge Transfer Spectra Observed with Some Compounds Containing the Nitro or the Carbonyl Group

Abstract

A new method, which proved to be useful for the theoretical study of electron migration for the monosubstituted benzene molecule, is employed to interpret strong absorption bands observed with various unsaturated compounds containing the nitro or the carbonyl group. Consequently, it is shown that these absorptions correspond to the transition between two energy levels produced by the interaction of the highest occupied level of the electron donating group with the lowest vacant one of the electron accepting group, and that theoretical values of transition energies and oscillator strengths evaluated by use of the present method are in very good agreement with the observed values. Furthermore, the present interpretation of these absorptions is discussed in comparison with the earlier resonance viewpoint.