Cyano(triphenylsilyl)phosphanide as a Building Block for P,C,N Conjugated Molecules

The cyano(triphenylsilyl)phosphanide anion was prepared as a sodium salt from 2‐phosphaethynolate. The electronic structure of this new cyano(silyl)phosphanide was studied via computational methods and its reactivity investigated using various electrophiles and Lewis acids, demonstrating its P‐ and N‐nucleophilicity. The ambident reactivity is in agreement with computations. The silyl group also shows lability and therefore the cyano(silyl)phosphanide can be considered as a phosphacyanamide synthon, [PCN]2−, and serves as building block for the transfer of a PCN moiety. Na[PCO] reacts with Ph3ECl (E=Si, Ge, Sn) and Na[N(SiMe3)2] to form the series of anions [Ph3E−P−CN]−. The silylated anion forms PCN heteroallenes in reactions with tetrel chlorides and binds via nitrogen to triphenylborane. P‐nucleophilicity and lability of the silyl substituent in [Ph3Si−P−CN]− are evidenced in reactions with isocyanates and carbodiimides, which afford phosphorus analogues of cyanourea and 2‐cyanoguanidine.