Some studies of benzenoid-quinonoid resonance. Part 1.—General theory and applications to the structure of the pyridones and to the stability of Wheland intermediates

Abstract

A π SCF programme with bond length and bond angle optimization is used to calculate the structure and stabilities of the pyridones and the stability of Wheland intermediates. Contrary to earlier calculations the β pyridone is not found to have a very unfavourable π electron energy. Bond length optimization is found to have an important effect on the localization energies of the hydroxynaphthalenes. Calculations on the 2–6 naphthalene system, for which a cross-ring quinonoid structure can be drawn, give a stabilization of 0.23 eV for optimum bond lengths relative to a structure with bond lengths appropriate to the “non resonance” 2–7 system.