Kinetic isotope effects for silylene insertions into oxygen-hydrogen and silicon-hydrogen bonds

Kinetic isotope effects have been measured for the insertion of both deuterated and undeuterated photochemically generated dimethylsilylene and methylphenylsilylene into the S-H bonds and 0-H bonds. Two possible mechanisms are preposed for the insertion of silylenes into the 0-H bonds of alcohols. Both are consistent with observed isotope effects. The mechanisms have essentially the same transition state for the rate-determining and product-determining steps, and are both consistant with previously reported solvent effects. On the basis of currently available experimental data, it was deemed impossible to specify with certainty the reaction mechanism. (BLM)