Synthesis and reactivity of the stable silylene N,N '-di-tert-butyl-1,3-diaza-2-sila-2-ylidene

The synthesis and several reactions of the stable silylene 1 (N,N'-di-tert- butyl-1,3-diaza-2-sila-2-ylidene) are reported. Overreduction of 1 with alk ali metals results in the formation of a dimeric dianion, which can be trap ped with a proton source to give the dihydride derivative 9. In the solid s tate or in concentrated solutions, 1 undergoes a reversible conversion into the novel tetrameric disilene, 10. 1 reacts with ethanol, phenol, and wate r via insertion into the O-H bond, and with iodomethane by insertion into t he C-I bond. A reaction of 1 with the diene 2,3-dimethyl-1,3-butadiene affo rds the silacyclopentene, 15. This reaction is markedly different from the one found for the unsaturated analog of the silylene, 2, which catalyzes th e conversion of this diene into a highly cross-linked polymer.