Electronic Structures and Spectra of Some Nitrogen-Oxygen Compounds

The electronic structures and spectra of nitrite ion, nitrosomethane, nitrosamine, and nitrate ion have been calculated by a semiempirical method, which includes both the π-electron system and, in a more limited manner, the σ-electron system. The calculated transition energies and intensities for the first three compounds above agree fairly satisfactorily with experiment. For nitrate ion, however, it seems possible that the lowest observed transition may be a very low energy n→σ* transition, σ* being an antibonding σ orbital, rather than one of the n→π* transitions considered in the present work.