om0003887_si_001.pdf (752.52 kB)
Stoichiometric and Catalytic Activation of Si−H Bonds by a Triruthenium Carbonyl Cluster, (μ3,η2:η3:η5-acenaphthylene)Ru3(CO)7: Isolation of the Oxidative Adducts, Catalytic Hydrosilylation of Aldehydes, Ketones, and Acetals, and Catalytic Polymerization of Cyclic Ethers
journal contribution
posted on 2000-08-05, 00:00 authored by Hideo Nagashima, Akihiro Suzuki, Takafumi Iura, Kazuhiro Ryu, Kouki MatsubaraTreatment of the ruthenium cluster (μ3,η2:η3:η5-acenaphthylene)Ru3(CO)7 (1) with stoichiometric amounts of trialkylsilanes results in liberation of a CO ligand followed by
oxidative addition of a Si−H bond. The trinuclear silyl complexes (μ3,η2:η3:η5-acenaphthylene)Ru3(H)(SiR3)(CO)6 (2) were isolated in good yield. They were characterized by NMR
spectroscopy and X-ray crystallography. Compound 1 catalyzes the hydrosilylation of olefins,
acetylenes, ketones, and aldehydes. In particular, the reactions of aldehydes and ketones
proceed at room temperature to form the corresponding silyl ethers in good yield; the catalytic
activities are superior to those with RhCl(PPh3)3. The RhCl(PPh3)3-catalyzed hydrosilylation
of ketones with Me2(H)SiCH2CH2Si(H)Me2 results in selective reaction of only one Si−H
terminus, while similar reactions, when catalyzed by 1, allow utilization of both Si−H groups.
Significantly different regio- and stereoselectivities, compared with those obtained in
reactions catalyzed by RhCl(PPh3)3, also were observed in the hydrosilylation of α,β-unsaturated carbonyl compounds and 4-tert-butylcyclohexanone, respectively. The reactions
with acetals and cyclic ethers also take place under similar conditions. The reaction of
trialkylsilanes with an excess of a cyclic ether resulted in ring-opening polymerization.
Polymerization of THF was investigated as a representative example. Treatment of
trialkylsilanes with an excess of THF (10−102 equiv with respect to silanes) in the presence
of a catalytic amount of 1 resulted in production of polytetrahydrofuran with Mn = 1000−200 000 and Mw/Mn = 1.3−2.0. Changing the ratio of THF to HSiR3 can control the molecular
weight. NMR studies suggested that the structure of the polymer is R3SiO−[(CH2)4O]n−CH2CH2CH2CH3. Mechanistic considerations based on differences in the catalytic activities
between the catalysts 1 and 2 are discussed.
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Oxidative AdductsCO ligandcyclic ethertrialkylsilanes resultsNMR studiesTHFrepresentative example4 OMechanistic considerationsCatalytic PolymerizationCatalytic Activationcatalysts 1cyclic etherssilyl ethersCyclic Ethers TreatmentTriruthenium Carbonyl ClusterM nCHRhClketoneoxidative additionstoichiometric amountsCatalytic HydrosilylationacenaphthylenehydrosilylationCompound 1 catalyzesNMR spectroscopyHSiR 3carbonyl compoundsroom temperature
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