From a zwitterionic phosphasilene to base stabilized silyliumylidene-phosphide and bis(silylene) complexes.

The reactivity of ylide-like phosphasilene 1 [LSi(TMS)═P(TMS), L = PhC(NtBu)2] with group 10 d10 transition metals is reported. For the first time, a reaction of a phosphasilene with a transition metal that actually involves the silicon–phosphorus double bond was found. In the reaction of 1 with ethylene bis(triphenylphosphine) platinum(0), a complete silicon–phosphorus bond breakage occurs, yielding the unprecedented dinuclear platinum complex 3 [LSi{Pt(PPh3)}2P(TMS)2]. Spectroscopic, structural, and theoretical analysis of complex 3 revealed the cationic silylene (silyliumylidene) character of the silicon unit in complex 3. Similarly, formation of the analogous dinuclear palladium complex 4 [LSi{Pd(PPh3)}2P(TMS)2] from tetrakis(triphenylphosphine) palladium(0) was observed. On the other hand, in the case of bis(cyclooctadiene) nickel(0) as starting material, a distinctively different product, the bis(silylene) nickel complex 5 [{(LSi)2P(TMS)}Ni(COD)], was obtained. Complex 5 was fully characterized incl...