MOLECULAR ORBITAL TREATMENT OF SOME PYRAZINES.

Abstract

A molecular orbital treatment of phenazine, dicyclopenta pyrazine and dicyclohepta pyrazine is given. The resonance energies of these molecules, their z-electron density distribution and bond orders have been calculated. The resonance energy value calculated for phenazine by the m.o. method agrees with that experimentally determined. Although dicyclopenta pyrazine and dicyclohepta pyrazine have not yet been chemically  prepared the calculated resonance energies are comparable with that of phenazine. In this connection the similarity between these two pyrazines and pentalene and heptalene has been pointed out. The rule postulated by Longuet-Higgins and Coulson (1949) ttat the net charge in a diaza hydrocarbon should be the sum of the net charges for the corresponding two monoaza hydrocarbons has been confirmed by results obtained by direct solution of the secular determinants in the respective cases.