Current State of [Fe]‐Hydrogenase and Its Biomimetic Models

Abstract

[Fe]‐hydrogenase, the third type of natural hydrogenase, is capable to heterolytically activate hydrogen molecule and transfer the resulting hydride to an unsaturated substrate, making it a promising hydrogenation catalyst. Over the last three decades, fruitful results on this enzyme have been achieved. In this review, we have summarized the major progresses about this enzyme including its structural characterisation, catalytic mechanism, cofactor biosynthesis, mimetic model development as well as artificial enzymes construction. In the meanwhile, challenges and opportunities of this enzyme and its mimetic systems in the application of synthetic chemistry and others are discussed.

2-Pyridonates: a versatile ligand platform in 3d transition metal coordination chemistry and catalysis

“…Hydrogenases are a class of metalloenzymes that reversibly catalyze the splitting of H 2 and its generation. 8…”

“…Hydrogenases are a class of metalloenzymes that reversibly catalyze the splitting of H 2 and its generation. 8 Three types of hydrogenases with 3d transition metal centers are known: [NiFe]-, [FeFe]- and [Fe]-hydrogenases. Unlike the bimetallic [NiFe]- and [FeFe]-hydrogenases, the [Fe]-hydrogenase contains only one redox-innocent metal ion and lacks the prototypical iron–sulfur cluster unit.…”

“…7 The metal–pyridinol motif has a natural role in the active site of the [Fe]-hydrogenase metalloenzyme (Scheme 1b). 8 The natural occurrence of such, and related, transition metal oxypyridine complexes and their mechanistic role in biocatalytic pathways has been serving as a great inspiration for the development of biomimetic models and related metal complexes. 9,10 2-Pyridonates are LX-type donors and important members of the 1,3- N , O -hetero-bidentate ligand family (Scheme 1c).…”

Insights from Enzymatic Catalysis: A Path towards Bioinspired High‐Performance Electrocatalysts

“…To achieve the catalytic performance, a combination of structural research and DFT computational analysis indicated the roles of frustrated Lewis pairs, a bound internal base for molecular hydrogen cleavage, the resulting pK a after ligands and the second coordination sphere, while also showing that in biomimetic catalysis, the replacement of the metal ion should also be investigated. [127][128][129][130] The usage of a Ni-based DuBois catalyst ([Ni(P 2 R' N 2 R'' ) 2 ] 2 + core) for molecular hydrogen generation is an example that brings an inner (first and second) coordination sphere with a high electroactive core, [131] and an outer coordination sphere driving high aqueous solubility due to the presence of phosphonic groups. [132] The association with a phosphonated bipyridine-based Ru(II) photosensitizer allowed for a combined photocatalytic H 2 evolution in water.…”

[Fe]-Hydrogenase-Inspired Proton-Shuttle Installation in a Molecular Cobalt Complex for High-Efficiency H2 Evolution Reaction

“…In all of these catalysts, the proton-shuttle/relay motifs facilitate reducing the overpotential (η, the excess potential required for catalysis over the thermodynamic potential) and/or enhancing the reaction rate (turnover frequency, TOF). In [Fe]-hydrogenase, the third category of hydrogenase enzymes, a pyridinone/pyridinol-based proton shuttling group assists the reversible heterolytic H 2 -cleavage/formation in the nonredox hydride transfer-based enzymatic cycle. − Artificial [Fe]-hydrogenase active site models having nearly ideal biomimetic primary coordination sphere around a nonredox metal center have previously been reported to mimic the exact reactions of the enzyme. − However, improvising the power of pyridinone/pyridinol-based proton shuttle function, in order to develop highly efficient transition-metal-based artificial H 2 evolving electrocatalysts, is hitherto unknown and yet to be examined. To achieve such a goal, the electrochemical H 2 -generation reaction can be facilitated by a redox-active metal center with the formation and proper positioning of the metal-hydride (M–H) bond and the “protonated” pyridinol form of the adjacent proton shuttle motif in a suitable transition-metal complex.…”