Highly Selective Substitution and Insertion Reactions of Silylenes in a Metal-Coordinated Polyphosphide

Selective substitution and insertion reactions of silylenes into the cyclo-P5 ring of [Cp*Fe­(η5-P5)] are reported. The selective substitution of one P atom by an isoelectronic [LSi] fragment (L = PhC­(NtBu)2) leads to [(η4-P4SiL)­FeCp*] and [LSi­(Cl)P-SiL(Cl)2]. To elucidate the reaction mechanism, [{LSi­(N­(SiMe3)2)}­{(η4-P5)­FeCp*}], in which the silicon atom binds to the cyclo-P5 ring, was synthesized as a model compound for the reaction intermediate. The insertion of [LSi-SiL] into the cyclo-P5 ring of [Cp*Fe­(η5-P5)] resulted in [{η4-P5(SiL)2}­FeCp*] featuring a cyclo-P5(SiL)2 ring, which corresponds to the largest silicon–polyphosphorus ring known in a complex.