Radical isomerization of 9,10-dihydro-9,10-disilaanthracene derivatives: stabilization factor of silyl radicals

In order to examine the nature of the silyl radical in the disilaanthracene framework, separation and radical isomerization of the cis and trans isomers of the disilaanthracene derivatives were investigated. When a pentane solution of the disilaanthracene derivative was irradiated with a 400 W mercury lamp in the presence of DTBP for 4 h, both isomers readily isomerized to give a mixture of cis and trans isomers in a ratio of ca. 50:50. However, no such isomerization reaction of 9,10-dihydro-9-silaanthracene derivatives occurred under similar conditions.