Semiempirical molecular orbital studies of phthalocyanines

Theπ andσ lone pair electron system of the phthalocyanine molecule has been studied by a semiempirical SCF-MO method. Electronic transitions of bothπ-π ^* andn-π ^* types have been considered. The excited states have been calculated by means of the method of superposition of configurations where all singly excited states are included. Assignments for the electronic spectrum of phthalocyanine could be made in good agreement with experiment. The position of the lowest electronically allowedn-π ^* transition is predicted to be found in the region of the strong Soret band.