Electronic Spectra and Structures of Tropone and Heptafulvene

State energies, transition moments, and reactivity indices for tropone and heptafulvene are calculated by the semiempirical SCF—MO method including all singly excited configuration interactions. The results of the calculations are listed in Table II, III, and IV. In heptafulvene there are three absorption bands. The band of longest wavelength and the band of next-longest wavelength are transitions 1A1—1B1 and 1A1—1A1, respectively. In tropone these two transitions shift closely to each other and make one band. There are two absorption bands in tropone. Since π electrons of tropone and heptafulvene localize partially upon double bonds, the lowest triplet energy is lower than that of aromatic compounds which contain the same number of π electrons as tropone or heptafulvene.