The Facile Generation of a Tetramethyleneethane Type Radical Cation and Biradical Utilizing a 3,4-Di(α-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(α-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·+, λmax = 392 nm) and the corresponding singlet biradical (17a**, λmax = 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. [ABSTRACT FROM AUTHOR]