Spectroscopic and reactivity studies of platinum-silicon monomers and dimers

Mononuclear Pt-Si-containing complexes with the general formulas (Ph3P)(2)Pt(H)(SiAr2H) and (Ph3P)(2)Pt(SiAr2H)(2) were produced at low temperature from the reaction of the secondary arylhydrosilanes Ph2SiH2, C12H8SiH2 (silafluorene), and C2OH24SiH2 (3,7-di-tert-butylsilafluorene) with (Ph3P)(2)Pt(A(2)-C2H4). When solutions of the mononuclear complexes were run at low temperature and then warmed to room temperature, or when the reactions were run at room temperature or above, dinuclear Pt-Si-containing complexes were produced, [(Ph3P)Pt(mu-eta(2)-HSiAr2)](2) (Ar) Ph(4)) and [(Ph3P)(2)Pt(H)(mu-SiAr2)(mu-eta(2)-HSiAr2) Pt(PPh3)] (Ar-2 = C12H8 (8), C12H24 (15); both fluxional). A mechanism is proposed for the formation of the unsymmetrical dinuclear complexes (8 and 15) that involves a bimolecular reaction between two mononuclear species, (Ph3P)(2)Pt(H)(SiAr2H) and (Ph3P) Pt(H)(SiAr2H). VT-NMR studies of complexes 8 and 15 illustrate that a fluxional process occurs which can be explained by elimination and recoordination of a PPh3 ligand. Complex 15 reacted with added P(p-Tol)(3) to produce a mixture of dinuclear products consistent with the presence of both types of phosphines in the dinuclear complexes. Reaction of the dinuclear complex 8 with the mononuclear complex 16 as well as the elevated-temperature reaction between 8 and 15 will be described.