Cyclic (Amino)(Phosphonium Bora-Ylide)Silanone: A Remarkable Room-Temperature-Persistent Silanone.

A silanone substituted by bulky amino and phosphonium bora-ylide substituents has been isolated in crystalline form. Thanks to the exceptionally strong electron-donating phosphonium bora-ylide substituent, the lifetime at room temperature of the silanone is dramatically extended (t1/2 =4 days) compared to the related (amino)(phosphonium ylide)silanone VI (t1/2 =5 h), allowing easier manipulation and its use as precursor of new valuable silicon compounds. The interaction of silanone with a weak Lewis acid such as MgBr2 increases further its stability (no degradation after 3 weeks at room temperature).