56 insertion reactions between seven silylenes and eight reactants were investigated using B3LYP/cc-pVTZ method. The reaction energies and the stability of the silylenes are in good correlation. Silaimidazole-2-ylidene gives the highest reaction energies while Kira's stable five membered ring dialkylsilylene shows the smallest reaction energies. All the reaction energies and activation energies of the six-membered ring diazasilylene ({HC[CMeN(R)]2}Si, R = 2,6-diisopropylphenyl) were found equal to that of the saturated five-membered diazasilole. The sum of the reaction free energies (ΔG) and activation free energies (ΔG‡) of a reaction depend on the reactant but are independent of the silylene.
