Reactivity of silylene complexes

The metal–silicon bond in silylene complexes is highly polarized in a M^δ−–Si^δ+ manner. Accordingly, silylene complexes show high reactivities toward nucleophiles, such as water, alcohols, ketones, isocyanates, and phosphorus ylides. The metal–silicon double bond can also activate aromatic carbon–hydrogen bonds. Among the various silylene complexes, silyl(silylene) complexes occupy a unique position; these complexes undergo intramolecular 1,3-migration, which is postulated as a key step in the metal-mediated redistribution of substituents on organosilicon compounds. Alkyl(silylene) complexes are not stable and undergo 1,2-alkyl migration to yield alkylsilyl complexes.