Mesolytic scission of C-C bonds as a probe for photoinduced electron transfer reactions of quinones

A simple unimolecular C-C bond scission in radical cations is used as a probe for photoinduced electron transfer reactions of chlorinated benzoquinones. THe dynamics of back-electron transfer in these two types of radical ion pairs are examined using the fragmentation rates and the quantum yields. Products with high quantum yields were observed for the triplet ion pairs formed by interception of excited state quinones, while the singlet ion pairs formed by irradiation of the charge-transfer complexes between the quinones and the donors undergo reactions with lower efficiency.