- A Ni0(η2-(Si-H))(η2-H2) Complex That Mediates Facile H Atom Exchange between Two σ-Ligands
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σ-adduct complexes of low-valent, late first-row metal complexes are highly unusual, and this is particularly true of d10 systems. We have discovered a nickel/phosphine/silyl system that undergoes reaction with H2 in solution to gene
- Connor, Bridget A.,Rittle, Jonathan,Vandervelde, David,Peters, Jonas C.
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- Iron-catalysed chemo-, regio-, and stereoselective hydrosilylation of alkenes and alkynes using a bench-stable iron(II) pre-catalyst
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The chemo-, regio-, and stereoselective iron-catalysed hydrosilylation of alkenes and alkynes with excellent functional group tolerance is reported (34 examples, 41-96% yield). The catalyst and reagents are commercially available and easy to handle, with the active iron catalyst being generated in situ, thus providing a simple and practical methodology for iron-catalysed hydrosilylation. The silane products can be oxidised to the anti-Markovnikov product of olefin hydration, and the one-pot iron-catalysed hydrosilylation-oxidation of olefins to give silane(di)ols directly is also reported. The iron pre-catalyst was used at loadings as low as 0.07 mol%, and displayed catalyst turnover frequencies (TOF) approaching 60,000 molh-1. Initial mechanistic studies indicate an iron(I) active catalyst.
- Greenhalgh, Mark D.,Frank, Dominik J.,Thomas, Stephen P.
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supporting information
p. 584 - 590
(2014/05/20)
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- Hydrogenation and silylation of a double-cyclometalated ruthenium complex: Structures and dynamic behavior of hydrido and hydridosilicate ruthenium complexes
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A double-cyclometalated ruthenium complex containing a chiral tripodal phospholane has been prepared by reaction with [Ru(η4-COD) (η3-methylallyl)2] via elimination of isobutene. The ruthenium-carbon bonds of this compound were reversibly cleaved by H 2, resulting in an equilibrium between a tri- and a tetrahydride (4 and 5). T1 relaxation time measurements revealed the nonclassical nature of the fluctuating hydrides. Release of the gas led to complete re-formation of the cyclometalated compound. Reaction of 3 with D2 afforded D10-5, in which six ortho-phenyl protons and four hydrides were replaced by deuterium. Furthermore, diphenylsilane was found to readily insert into one Ru-C bond to form 6, containing a κ3- dihydridosilicate fragment. On the basis of deuterium labeling experiments, the fast exchange between the two hydrides was shown to include a reductive elimination/oxidative addition step involving the remaining metalated phenyl group. Again, pressurization of 6 with H2 resulted in reversible cleavage of the remaining Ru-C bond, yielding the corresponding trihydride 7.
- Scherl, Peter,Wadepohl, Hubert,Gade, Lutz H.
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p. 4409 - 4415
(2013/09/02)
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- Hydrosilylation with biscarbene Rh(I) complexes: Experimental evidence for a silylene-based mechanism
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A detailed study investigating the mechanism of the hydrosilylation of 4-F-acetophenone by N-heterocyclic biscarbene rhodium(I) complexes was performed, delivering substantial experimental evidence for a recently proposed catalytic cycle and explaining the observed side-product formation. Labeling experiments, silylene trapping reactions, and specific catalytic reactions were employed to substantiate each step of the catalytic cycle and explain the differences observed for different types of chiral catalysts. It is further shown that hydrosilylation and dehydrocoupling reactions with dihydrosilanes are mechanistically related.
- Gigler, Peter,Bechlars, Bettina,Herrmann, Wolfgang A.,Kuehn, Fritz E.
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experimental part
p. 1589 - 1596
(2011/04/16)
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