A reaction scheme for the rearrangement of trimethylsilyl(methyl)silylene (Me3Si–S̈i–Me) discovered in a pioneering work of organosilicon chemistry (Wulff et al., J Am Chem Soc 1978, 100, 6236) was studied by the MP2 and DFT methods. We report a thermal reaction scheme for the rearrangement of Me3Si–
$\ddot{{\rm Si}}$–Me with the structures and energies of various silicon species along the isomerization paths, that can account for the experimentally found product ratio. The experimental product ratio is in good agreement with the theoretical one derived from the Gibbs free energy changes calculated in the present study. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010