C–Si bond dissociation in highly excited triplet states of phenybenzylphenylsilanes studied by stepwise two-color laser photolysis in solution

C–Si Bond dissociation in highly excited triplet (Tn) states of p-phenylbenzylphenylsilanes (PBPS) was found using stepwise two-color laser photolysis techniques. PBPS undergo the C–Si bond cleavage in excited singlet states with quantum yields of 0.02–0.03, whereas they did not decompose in the lowest triplet (T1) states. Upon the second laser excitation of the T1 states, the C–Si bonds were found to cleave with quantum yields of 0.04–0.06. From the viewpoint of the bond dissociation energies of the C–Si bonds, the dissociation profile in the Tn state of PBPS was discussed.