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Subject: Homogeneous catalysis × WGL Institute: LIKAT ×

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Now showing 1 - 3 of 3
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    Activation, deactivation and reversibility phenomena in homogeneous catalysis : A showcase based on the chemistry of rhodium/phosphine catalysts
    (Basel : MDPI, 2019) Alberico, Elisabetta; Möller, Saskia; Horstmann, Moritz; Drexler, Hans-Joachim; Heller, Detlef
    In the present work, the rich chemistry of rhodium/phosphine complexes, which are applied as homogeneous catalysts to promote a wide range of chemical transformations, has been used to showcase how the in situ generation of precatalysts, the conversion of precatalysts into the actually active species, as well as the reaction of the catalyst itself with other components in the reaction medium (substrates, solvents, additives) can lead to a number of deactivation phenomena and thus impact the efficiency of a catalytic process. Such phenomena may go unnoticed or may be overlooked, thus preventing the full understanding of the catalytic process which is a prerequisite for its optimization. Based on recent findings both from others and the authors’ laboratory concerning the chemistry of rhodium/diphosphine complexes, some guidelines are provided for the optimal generation of the catalytic active species from a suitable rhodium precursor and the diphosphine of interest; for the choice of the best solvent to prevent aggregation of coordinatively unsaturated metal fragments and sequestration of the active metal through too strong metal–solvent interactions; for preventing catalyst poisoning due to irreversible reaction with the product of the catalytic process or impurities present in the substrate. © 2019 by the authors.
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    Formic Acid Dehydrogenation by a Cyclometalated κ3-CNN Ruthenium Complex
    (Weinheim : Wiley-VCH, 2020) Léval, Alexander; Junge, Henrik; Beller, Matthias
    Hydrogen utilization as a sustainable energy vector is of growing interest. We report herein a cyclometalated ruthenium complex [Ru(κ3-CNN)(dppb)Cl], originally described by Baratta, to be active in the selective dehydrogenation (DH) of formic acid (FA) to H2 and CO2. TON's of more than 10000 were achieved under best conditions without observation of CO (detection limit 10 ppm). The distinguished behavior of the catalyst was explored varying the starting conditions. Our observation revealed the complex [Ru(κ3-CNN)(dppb)(OOCH)] as key species in the catalytic cycle. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
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    Palladium-catalyzed synthesis of aldehydes from aryl iodides and formic acid with propylphosphonic anhydride as the activator
    (London : Nature Publishing Group, 2018) Wu, Xiao-Feng
    An interesting palladium-catalyzed carbonylative procedure for the synthesis of aromatic aldehydes from aryl iodides has been developed. By using propylphosphonic anhydride as the activator for formic acid, moderate to good yields of the corresponding aldehydes were produced with formic acid as the carbonyl and hydrogen donors. Interestingly, neither additional phosphine ligand nor inert gas protection is needed here.