The facile generation of a tetramethyleneethane type radical cation and biradical utilizing a 3,4-di(alpha-styryl)furan and a photoinduced ET and back ET sequence.

Product analyses and nanosecond time-resolved spectroscopy on laser flash photolysis were studied for the photoinduced electron-transfer reaction of 3,4-di(alpha-styryl)furan (6a). A combination of these results, kinetic, density functional theoretical (DFT), and time-dependent DFT analyses enabled assignment of the absorption to the tetramethyleneethane (TME)-type radical cation (7a*+, lambda(max) = 392 nm) and the corresponding singlet biradical ((1)7a**, lambda(max) = 661 nm). These two intermediates were mechanistically linked to each other with a facile back electron-transfer reaction. The present studies provide a new method for the generation of aryl-substituted TME-type intermediates.