The Triplet-Triplet Absorption Spectra and Electronic Structures of Some Cyano-Substituted Benzenes

Abstract
Triplet-triplet (T–T) absorption bands were observed at 300, 297, and 320 nm for m- and p-dicyanobenzenes, and 1,3,5-tricyanobenzene, respectively. The nature of the observed spectra was investigated by calculating the wave functions of the triplet states and by analyzing them by the configuration analysis method. It was concluded that the T–T absorption bands of m- and p-dicyanobenzenes, and 1,3,5-tricyanobenzene correspond essentially to the transition from the locally (within the benzene ring) excited state to the intramolecular charge-transfer state.