PHOTOCHEMISTRY OF 1-ARYL-4-(PENTAMETHYLDISILANYL)-1,3-BUTADIYNES

Abstract

All the 1-aryl-4-(pentamethyldisilanyl)-1,3-butadiynes (1a-d) synthesized show strong phosphorescence emissions with triplet energies around 218-260 kJ/mol. Laser photolysis of 1-(p-nitrophenyl)-4-(pentamethyldisilanyl)-1,3-butadiyne (1d) in polar solvents results in the formation of an interesting transient (zwitterion species) through intramolecular electron transfer from disilanyl to the nitro group in the triplet excited state. Irradiation of 1d in methanol or ethanol gives 1-(p-nitrophenyl)-1,3-butadiyne (8) through C-Si bond cleavage from the transient. Photolysis of 1-phenyl-4-(pentamethyldisilanyl)-1,3-butadiyne (1a), 1-(1-naphthyl)-4-(pentamethyldisilanyl)-1,3-butadiyne (1b), and 1-(p-methoxyphenyl)-4-(pentamethyldisilanyl)-1,3-butadiyne (1c) in methanol yields photoaddition products (2-7) through silacyclopropene intermediates.