Photoinduced electron-transfer reactions of arylmethyl-substituted 14 group compounds: Photoarylmethylation and photooxygenation

Article abstract of DOI:10.1246/bcsj.66.3747

Photoreactions of arylmethylsilanes, -germane, and -stannane with 1,4- dicyanonaphthalene (DCN) and 9, 10-dicyanoanthracene (DCA) were studied under various conditions. The arylmethylation of DCN and DCA occurred in the photoreaction under nitrogen atmosphere, whereas the oxygenation of the arylmethyl organometallic compounds occurred in the photoreaction under oxygen atmosphere. Key intermediates in these reactions in acetonitrile were radical ions which were generated via photoinduced electron transfer from the arylmethyl organometallic compounds to the excited singlet of DCN or DCA. The cleavage of the carbon-metal bond of the radical cations of the arylmethyl compounds resulted in the formation of arylmethyl radicals. The radicals reacted then with the radical anions of DCN and DCA to produce the arylmethylated compounds or reacted with oxygen to produce the oxygenated compounds. The efficiency of the photoreactions was affected by solvents and added materials to the reaction systems. In the photoreactions in benzene, the exciplexes of the type ¹[A-ArCH₂MR₃]* or the triplexes of the type [A-C₆H₆-ArCH₂MR₃]* (A=DCN, DCA) were involved as intermediates. The reactivity features of the photoreactions are discussed.