Base-Stabilized Cationic Silyne with a π-Accepting Phosphonio Substituent.

A base-stabilized C -phosphonio- Si -amino-silyne 3 was synthesized, using an original method, through a coupling reaction between two Lewis-base-stabilized low-valent species: a silyliumylidene ion 1 and a P,S-bis-ylide 2 [C(0)-complex]. This new isolable cationic silyne 3 displays remarkably high stability at room temperature [ t 1/2 = 7 days in tetrahydrofuran (THF)] and a unique silyne reactivity thanks to the effect of phosphonio substituent.