SILICON-COMPOUNDS WITH STRONG INTRAMOLECULAR STERIC INTERACTIONS - 68- SILYLENE REACTIONS WITH NITROGEN MULTIPLE BONDS - ADDITIONS AND REARRANGEMENTS

Reactions of the sterically encumbered silylenes R2Si: (R = 2,4,6-Me3C 6H2, 2,4,6-iPr(3)C(6)H(2)) with azobenzene are thought to proceed via the [2+1] cycloaddition products, followed by insertion of the N-N sin gle bond into the ortho-C-H bond of one of the phenyl rings or into th e C-HMe2 bond of one of the ortho-isopropyl groups to furnish the 1,3- diaza-2-silaindan (4) or 1-aza-2-silaindan (5) derivatives, respective ly. The reactions of these silylenes with 1-adamantyl azide seem to pr oceed through the silanimines and 4-azahomoadamantene intermediates wh ich, by [2+2] cycloadditions, afford the 1,3-diaza-2-silacyclobutane d erivatives 11 and 12. The structures of 4, 5, 11, and 12 were determin ed by X-ray crystallography.