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

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 life-time at room temperature of silanone 2 is dramatically extended (t1/2 = 4 days) compared to the related (amino)(phosphonium-ylide)silanone (t1/2 = 5 hours), 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).