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A New Ligand Design Based on London Dispersion Empowers Chiral Bismuth-Rhodium Paddlewheel Catalysts.

ABSTRACT: Heterobimetallic bismuth-rhodium paddlewheel complexes with phenylglycine ligands carrying TIPS-groups at the meta-positions of the aromatic ring exhibit outstanding levels of selectivity in reactions of donor/acceptor and donor/donor carbenes; at the same time, the reaction rates are much faster and the substrate scope is considerably wider than those of previous generations of chiral [BiRh] catalysts. As shown by a combined experimental, crystallographic, and computational study, the new catalysts draw their excellent application profile largely from the stabilization of the chiral ligand sphere by London dispersion (LD) interactions of the peripheral silyl substituents.

SUBMITTER: Singha S

PROVIDER: S-EPMC8154533 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Mixed-ligand complexes of paddlewheel dinuclear molybdenum as hydrodehalogenation catalysts for polyhaloalkanes.

Project description:We developed a hydrodehalogenation reaction of polyhaloalkanes catalyzed by paddlewheel dimolybdenum complexes in combination with 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (MBTCD) as a non-toxic H-atom source as well as a salt-free reductant. A mixed-ligated dimolybdenum complex Mo2(OAc)2[CH(NAr)2]2 (3a, Ar = 4-MeOC6H4) having two acetates and two amidinates exhibited high catalytic activity in the presence of n Bu4NCl, in which [ n Bu4N]2[Mo2{CH(NAr)2}2Cl4] (9a), derived by treating 3a with ClSiMe3 and n Bu4NCl, was generated as a catalytically-active species in the hydrodehalogenation. All reaction processes, oxidation and reduction of the dimolybdenum complex, were clarified by control experiments, and the oxidized product, [ n Bu4N][Mo2{CH(NAr)2}2Cl4] (10a), was characterized by EPR and X-ray diffraction studies. Kinetic analysis of the hydrodehalogenation reaction as well as a deuterium-labelling experiment using MBTCD-d8 suggested that the H-abstraction was the rate-determining step for the catalytic reaction.

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