Platinum and palladium complexes with metal-silicon bonds. New bonding, structures, and chemical properties

Studies on the Pt and Pd complexes with Si-containing ligands by the authors are reviewed. trans-[Pt(SiHPh2)(2)-(PMe3)(2)], the first Pt(II) complex with two silyl ligands at trans positions, is equilibrated with the thermodynamically more stable cis isomer in solution. The reaction of dimethyl acetylenedicarboxylate (Z-C equivalent to C-Z, Z = COOMe) with [Pt(SiHPh2)(2)(PMe3)(2)] produces 3-sila-1-propenylplatinum complex, cis-[Pt(CZ=CZSiHPh(2))(SiHPh2)(PMe3)(2)], and 4-sila-3-platinacyclobutene, [Pt(CZ=CZSiPh(2))(PMe3)(2)], depending on the reaction conditions. The former product is turned into the latter, accompanied by elimination of H2SiPh2. The spectroscopic data of cis-[Pt(CZ=CZSiHPh(2))(SiHPh2)(PMe3)(2)] as well as the crystallographic structure of the 3-sila-l-propenylplatinum with a chelating bisphosphine, [Pt(CZ=CZSiHPh(2))(SiHPh2)(dmpe)] (dmpe = 1,2-bis(dilnethylphosphino)ethane), indicate intramolecular interaction of the gamma-Si-H hydrogen of the ligand with the Pt center. The 4-sila-3-platinacyclobutene reacts with mono-substituted alkynes to produce various 5-sila-2-platina-1,4-cyclohexadienes via insertion of the C-C bond into the Pt-Si bond of the four-membered ring. [Pt(SiHPh2)(2)(PMe3)(2)] reacts with nitriles to cause double addition of the Si-H bonds to the C N triple bond, yielding [Pt{SiPh2N(CH2R)SiPh2}(PMe3)(2)] (R = Me and Ph). The reactions of H2SiPh2 and H2SiPhMe with [PdEt2(PMe3)(2)] afford dinuclear Pd complexes with bridging silyl ligands, [{Pd(PMe3)}{Pd(PMe3)}(mu-HSiPhR)(2)] (R = Me and Ph; n = 1 and 2). Pd-Pt heterobimetallic complexes with bridging diphenylsilyl ligands, [{Pd(PR3)}{Pt(PR3)(n)}(mu-HSiPh2)(2)] (R= Et and Cy (cyclohexyl); n = 1 and 2), are obtained from the reactions of bis(silyl)platinum(II) complexes with palladium(0)-phosphine complexes. The heterobimetallic complex with PEt3 ligands reacts with t-butyl isocyanide to afford a new disilaplatinacyclopentane, [Pt{SiPh2CH2N(t-Bu)SiPh2}(PEt3)-(CN-t-Bu)]. Heating of [Pt(SiHPh2)(2)(PMe3)(2)] at 80 degrees C in solution produces a trinuclear Pt complex with bridging diphenylsilylene ligands, [(Pt(PMe3))(3)(mu-SiPh2)(3)], which was characterized by X-ray crystallography, NMR spectroscopy, and theoretical calculations.