title: Asymmetric hydrogenation with highly active IndolPhos-Rh catalysts: kinetics and reaction mechanism.
abstract: The mechanism of the IndolPhos-Rh-catalyzed asymmetric hydrogenation of prochiral olefins has been investigated by means of X-ray crystal structure determination, kinetic measurements, high-pressure NMR spectroscopy, and DFT calculations. The mechanistic study indicates that the reaction follows an unsaturate/dihydride mechanism according to Michaelis-Menten kinetics. A large value of K(M) (K(M) = 5.01+/-0.16 M) is obtained, which indicates that the Rh-solvate complex is the catalyst resting state, which has been observed by high-pressure NMR spectroscopy. DFT calculations on the substrate-catalyst complexes, which are undetectable by experimental means, suggest that the major substrate-catalyst complex leads to the product. Such a mechanism is in accordance with previous studies on the mechanism of asymmetric hydrogenation reactions with C(1)-symmetric heteroditopic and monodentate ligands.
authors.affiliation: Supramolecular & Homogeneous Catalysis van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Wassenaar
authors.forename: Mark
authors.initials: M
authors.lastname: Kuil
authors.forename: Martin
authors.initials: M
authors.lastname: Lutz
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Spek
authors.forename: Joost N H
authors.initials: JN
authors.lastname: Reek
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D006865:Hydrogenation; D007700:Kinetics; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009943:Organophosphorus Compounds / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D000475:Alkenes; D008024:Ligands; D009943:Organophosphorus Compounds; D012238:Rhodium