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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]

Abstract: Mechanistic studies and product analyses were performed on the single electron transfer (SET) promoted photoamination reaction between 2,5-dimethylhexa-2,4-diene (1) and 9-cyanophenanthrene in order to gain a comprehensive understanding of the effects of additive metal salts. The product selectivity of this process was found to be dramatically increased by the addition of Mg2+ salts. An investigation involving the analyses of fluorescence and time-resolved absorption spectroscopic properties reveals that Mg2+ enhances the rate of the initial SET step and stabilizes the resulting radical ion pair in this photoreaction. [Copyright &y& Elsevier]