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Efficient Cluster-B...
Efficient Cluster-Based Catalysts for Asymmetric Hydrogenation of α-Unsaturated Carboxylic Acids.
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- Moberg, Viktor (författare)
- Lund University,Lunds universitet,Kemisk fysik,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Chemical Physics,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
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Duquesne, Robin (författare)
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Contaldi, Simone (författare)
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Röhrs, Oliver (författare)
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Nachtigall, Jonny (författare)
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Damoense, Llewellyn (författare)
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Hutton, Alan T (författare)
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- Green, Michael (författare)
- Lund University,Lunds universitet,Beräkningsbiologi och biologisk fysik - Genomgår omorganisation,Institutionen för astronomi och teoretisk fysik - Genomgår omorganisation,Naturvetenskapliga fakulteten,Computational Biology and Biological Physics - Undergoing reorganization,Department of Astronomy and Theoretical Physics - Undergoing reorganization,Faculty of Science
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Monari, Magda (författare)
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Santelia, Daniela (författare)
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Haukka, Matti (författare)
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- Nordlander, Ebbe (författare)
- Lund University,Lunds universitet,Kemisk fysik,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Chemical Physics,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
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(creator_code:org_t)
- 2012-08-13
- 2012
- Engelska.
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Ingår i: Chemistry: A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 18:39, s. 12458-12478
- Relaterad länk:
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http://dx.doi.org/10...
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https://lup.lub.lu.s...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- The new clusters [H(4) Ru(4) (CO)(10) (μ-1,2-P-P)], [H(4) Ru(4) (CO)(10) (1,1-P-P)] and [H(4) Ru(4) (CO)(11) (P-P)] (P-P=chiral diphosphine of the ferrocene-based Josiphos or Walphos ligand families) have been synthesised and characterised. The crystal and molecular structures of eleven clusters reveal that the coordination modes of the diphosphine in the [H(4) Ru(4) (CO)(10) (μ-1,2-P-P)] clusters are different for the Josiphos and the Walphos ligands. The Josiphos ligands bridge a metal-metal bond of the ruthenium tetrahedron in the "conventional" manner, that is, with both phosphine moieties coordinated in equatorial positions relative to a triangular face of the tetrahedron, whereas the phosphine moieties of the Walphos ligands coordinate in one axial and one equatorial position. The differences in the ligand size and the coordination mode between the two types of ligands appear to be reflected in a relative propensity for isomerisation; in solution, the [H(4) Ru(4) (CO)(10) (1,1-Walphos)] clusters isomerise to the corresponding [H(4) Ru(4) (CO)(10) (μ-1,2-Walphos)] clusters, whereas the Josiphos-containing clusters show no tendency to isomerisation in solution. The clusters have been tested as catalysts for asymmetric hydrogenation of four prochiral α-unsaturated carboxylic acids and the prochiral methyl ester (E)-methyl 2-methylbut-2-enoate. High conversion rates (>94 %) and selectivities of product formation were observed for almost all catalysts/catalyst precursors. The observed enantioselectivities were low or nonexistent for the Josiphos-containing clusters and catalyst (cluster) recovery was low, suggesting that cluster fragmentation takes place. On the other hand, excellent conversion rates (99-100 %), product selectivities (99-100 % in most cases) and good enantioselectivities, reaching 90 % enantiomeric excess (ee) in certain cases, were observed for the Walphos-containing clusters, and the clusters could be recovered in good yield after completed catalysis. Results from high-pressure NMR and IR studies, catalyst poisoning tests and comparison of catalytic properties of two [H(4) Ru(4) (CO)(10) (μ-1,2-P-P)] clusters (P-P=Walphos ligands) with the analogous mononuclear catalysts [Ru(P-P)(carboxylato)(2) ] suggest that these clusters may be the active catalytic species, or direct precursors of an active catalytic cluster species.
Ämnesord
- NATURVETENSKAP -- Biologi -- Biofysik (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences -- Biophysics (hsv//eng)
- NATURVETENSKAP -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)
Nyckelord
- cluster compounds
- asymmetric catalysis
- hydrogenation
- ruthenium
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Moberg, Viktor
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Duquesne, Robin
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Contaldi, Simone
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Röhrs, Oliver
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Nachtigall, Jonn ...
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Damoense, Llewel ...
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visa fler...
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Hutton, Alan T
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Green, Michael
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Monari, Magda
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Santelia, Daniel ...
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Haukka, Matti
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Nordlander, Ebbe
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