Reactivity of silylene complexes

The metal-silicon bond in silylene complexes is highly polarized in a Mdelta--Sidelta+ 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.