A series of μ-silylene complexes was synthesized by way of sequential Si−H and Si−C bond scission of tertiary silanes on diruthenium centers generated from Cp*Ru(μ-H)4RuCp* (1; Cp* = η5-C5Me5). While both bis- and mono(μ-diphenylsilylene) complexes, {Cp*Ru(μ-SiPh2)(μ-H)}2 (3a) and {Cp*Ru(μ-H)}2(μ-SiPh2) (4a), were obtained in the case of Ph3SiH, the reactions of 1 with Ph2MeSiH and PhMe2SiH exclusively afforded bis(μ-silylene) complexes, {Cp*Ru(μ-SiPhMe)(μ-H)} (3b- syn/anti ) and {Cp*Ru(μ-H)}2(μ-SiPhMe)(μ-SiMe2) (3c), respectively. The Si−C bond scission proceeded via prior π-coordination of the phenyl group of the intermediary formed silyl groups, which was supported by the fact that the reaction of 1 with (CH2CH)RSiH2 (R = Ph, Me) afforded exclusively the mono(μ-silylene) complex {Cp*Ru(μ-H)}2(μ-SiEtR) (4b, R = Me; 4c, R = Ph) as a result of intramolecular coordination of the vinyl group. Reaction of a mixture of 3b- syn and 3b- anti with PMe3 afforded the bis(μ-silylene) complex {Cp*Ru(μ-SiPhMe)}2(PMe3)(H)2 (5), which adopted only the syn structure with respect to the two bridging silylene ligands. Isomerization of the anti to the syn form arose from rotation of the bridging silylene ligands, which was confirmed by the VT-NMR studies of 3b- syn and 3c. While reactions of 3 with H2 and CO afforded respectively the bis(μ-silyl) complexes {Cp*Ru(μ-η2-HSiR2)}2(μ-H)(H) (2) and bis(μ-silylene) complexes containing two terminal carbonyl groups {Cp*Ru(CO)(μ-SiR2)}2 (6), liberation of the bridging silylene ligand of 4 was observed during the reaction with H2 and CO, together with formation of the mono(μ-silylene) complex {Cp*Ru(CO)}(μ-CO)(μ-SiR1R2) (8a, R1 = R2 = Ph; 8b, R1 = Me, R2 = Et; 8c, R1 = Ph, R2 = Et). X-ray diffraction studies were performed on 3c, 4a,b, 5, and 8a,b, and they clearly demonstrated the bridging silylene structures of these complexes.

A μ3-η(2):η(2):η(2)-silane complex, [(Cp*Ru)3(μ3-η(2):η(2):η(2)-H3SitBu)(μ-H)3] (2 a; Cp* = η(5)-C5Me5), was synthesized from the reaction of [{Cp*Ru(μ-H)}3(μ3-H)2] (1) with tBuSiH3. Complex 2 a is the first example of a silane ligand adopting a μ3-η(2):η(2):η(2) coordination mode. This unprecedented coordination mode was established by NMR and IR spectroscopy as well as X-ray diffraction analysis and supported by a density functional study. Variable-temperature NMR analysis implied that 2 a equilibrates with a tautomeric μ3-silyl complex (3 a). Although 3 a was not isolated, the corresponding μ3-silyl complex, [(Cp*Ru)3(μ3-η(2):η(2)-H2SiPh)(H)(μ-H)3] (3 b), was obtained from the reaction of 1 with PhSiH3. Treatment of 2 a with PhSiH3 resulted in a silane exchange reaction, leading to the formation of 3 b accompanied by the elimination of tBuSiH3. This result indicates that the μ3-silane complex can be regarded as an "arrested" intermediate for the oxidative addition/reductive elimination of a primary silane to a trinuclear site.

Two different classes of silicone-modified ligands were prepared: nitrile derivatives, 4'-[3-(organosilyl)propoxy]biphenyl-4-carbonitrile R'3SiC3H6OC6H4C6H4CN (R'3Si- = a: Me3SiOSiMe2-, b: (Me(3)SiO)2SiMe-, c: Me3SiO(Me2SiO)3SiMe2-, d: Me3SiO(Me2SiO)25SiMe2-); and, pyridine derivatives, isonicotinic acid 2-methoxy-4-[3-(organosilyl)propyl]phenyl ester R'3SiC3H6Ph(O)MeOCOC5H4N . Compounds and were bound to Pd and Pt using ligand substitution reactions with organometallic precursors to give (R3SiC3H6OC6H4C6H4CN)2PdCl2, (R3SiC3H6OC6H4C6H4CN)2PtCl2 and (R3SiC3H6C6H3(OMe)OC(O)C5H4N)PtCl2(eta(2)-1-octene). The polydimethylsiloxane (PDMS)-supported Pt and Pd compounds and had excellent solubility in both organic solvents and polysiloxanes. All the Pt compounds exhibited good catalytic activity for hydrosilylation of vinylsilanes. The PDMS-supported Pd compound also was effective catalyst for hydrosilylation of a diene, isoprene, with 1,1,1,3,3-pentamethyldisiloxane MM(H) to produce the 1,4-adduct Me3SiOSiMe2CH2CH=CMeCH2-H as a major product.

Both stereoisomers of disiloxane-bis(1-indenyl)-ansa-ferrocene, Fe(η 5 -inden-1-yl-SiMe 2 ) 2 O, 1, were prepared by the reaction of disiloxane-bis-1,3-inden-1′-yl anion with FeCl 2 ; the diastereomers were separated by column chromatography and recrystallized from n-heptane. A single-crystal X-ray diffraction study confirmed that each stereoisomer, racemic 1 r and meso 1 m , involves parallel bis-indenyl coordination to the Fe metal center. These isomers were also characterized by 1 H, 13 C, and 29 Si NMR and IR spectroscopy. Compounds 1 r and 1 m could each be transformed into the other diastereomer: the conversion was retarded by base, but accelerated under weakly acidic conditions. The mechanism of this process, investigated using deuterium labeling experiments, is consistent with a series of successive 1,5-suprafacial, sigmatropic silicon shifts.