Metal–Ligand Bifunctional Catalysis: The “Accepted” Mechanism, the Issue of Concertedness, and the Function of the Ligand in Catalytic Cycles Involving Hydrogen Atoms

2017/08/21 by Pavel A. Dub, John C. Gordon · 3 citations
Chemistry · Engineering · #Asymmetric Hydrogenation and Catalysis #Surface Chemistry and Catalysis #Metal-Organic Frameworks: Synthesis and Applications

paper · doi:10.1021/acscatal.7b01791

openalex publication_date 2017/08/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

For years, following the ideas of Shvo and Noyori, the core assumption of metal–ligand bifunctional molecular catalysis has relied on the direct involvement of the chelating ligand in the catalytic reaction via a reversible proton (H + ) transfer through cleavage/formation of one of its X–H bonds (X = O, N, C). A recently revised mechanism of the Noyori asymmetric hydrogenation reaction (Dub, P. A. et al. J. Am. Chem. Soc. 2014, 136, 3505) suggests that the ligand is rather involved in the catalytic reaction via the stabilization of determining transition states through N–H···O hydrogen-bonding interactions (HBIs) and not via a reversible H + transfer, behaving in a chemically intact manner within the productive cycle or predominantly in a chemically intact manner within productive cycles. By reexamining selected examples of computational mechanistic studies involving bifunctional catalysts from the literature in the years between 2012–2017, the purpose of this work is to point out common misconceptions in modeling concerted reactions and show that the actual stepwise nature of key transition states unveils a more complicated catalytic reaction pool (all conceivable catalytic pathways and their crossovers). Such a realization can not only potentially result in a reconsideration of the “accepted” mechanism but also lead us to a new conceptual understanding of the role that the ligand plays in the reaction. The ultimate goal of this paper is, therefore, to encourage the reader to reconsider the function of the ligand in catalytic cycles of hydrogenation/dehydrogenation with bifunctional catalysts, which until recently has relied almost exclusively on a chemically noninnocent ligand.

Citations

• Outer sphere hydrogenation catalysis
• Generalized Gradient Approximation Made Simple
• Practical Enantioselective Hydrogenation of Aromatic Ketones
• Semiempirical GGA‐type density functional constructed with a long‐range dispersion correction
• The Activated Complex in Chemical Reactions
• A consistent and accurateab initioparametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu
• Density-functional thermochemistry. III. The role of exact exchange
• Self-Consistent Equations Including Exchange and Correlation Effects
• Density functional theory is straying from the path toward the exact functional

Cited by

• A review on sulfonamides and their coordination compounds: Fighting diseases and catalytic applications
• The role of the metal-bound N–H functionality in Noyori-type molecular catalysts
• Metal-ligand cooperativity [wikipedia]

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