Chemically induced dynamic electron polarization studies on photolysis of hexaphenyldisilane, -digermane and -distannane

Abstract

EPR signals of the triphenylsilyl and triphenylgermyl radicals were observed for the first time in fluid solution by direct photolysis of hexaphenyldisilane and hexaphenyldigermane. Observed electron spin polarization was interpreted in terms of a triplet mechanism (TM). Along with the main signal, the ²⁹Si isotope signal was also observed and the polarization was tentatively explained by combination of a TM and a radical pair mechanism. An electron density on the silicon atom of the silyl radical was determined as 0.52 from the isotropic hyperfine coupling constant of ²⁹Si. The triphenylstannyl radical was not observed with the time resolution (ca. 80 ns) of our system.