Phosphorus Silicon Compounds from the Reduction of MesP(H)SiCl₂Ph/Carbene with and without Metal

MesP(H)SiCl₂Ph (Mes = 2,4,6-Me₃C₆H₂) (7) with a reactive Si–Cl and P–H bond can easily be reduced by KC₈ or alternatively by a carbene to give remarkable phosphorus silicon compounds. 7 is readily synthesized from the reaction of MesPH₂ sequentially with nBuLi and PhSiCl₃ in a 1:1:1 ratio. KC₈ reduction of MesP(H)SiCl₂Ph (7) in the presence of cyclic alkyl(amino) carbene (cAAC^Me) gives (MesPH)₃SiPh (8) and cAAC-stabilized Si₂Ph₂ (9). In addition, 9 might also be formed by the reduction of PhSiCl₃ using KC₈ in the presence of cAAC^Me. Treatment of MesP(H)SiCl₂Ph (7) with IiPr₂Me₂ (IiPr₂Me₂ = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) in a molar ratio of 1:2 results in HCl elimination as IiPr₂Me₂·HCl. The second equivalent of IiPr₂Me₂ was used to yield well-defined phosphasilene (10) containing a Ph(Cl)Si=PMes moiety. This unit will gain much application in ligand design because the chlorine atom can readily be replaced by other substituents.