Photophysical and photochemical processes of 9,10-dihydro-9-silaanthracenes: photochemical generation and electronic structure of 9-phenyl-9-silaanthracene

Photophysical processes of 9,10-dihydro-9-silaanthracene (1) and its 9-phenyl derivative (2) have been studied in 3-methylpentane at 77 K. Photolyses of these compounds have been carried out at 77 K and reaction intermediates have been studied. Carbon-centered radicals and silylenes have been observed for 1, while for 2, formation of carbon-centered radicals and 9-phenyl-9-silaanthracene has been confirmed by use of UV–vis absorption spectrum, fluorescence spectrum, fluorescence polarization and results of semi-empirical MO calculations. The electronic structure of 9-silaanthracene has been discussed in comparison with that of anthracene.