Reactions of [FeFe]-hydrogenase models involving the formation of hydrides related to proton reduction and hydrogen oxidation

Abstract

[FeFe]-hydrogenases are enzymes in nature that catalyze the reduction of protons and the oxidation of H2 at neutral pH with remarkably high activities and incredibly low overpotential. Structural and functional biomimicking of the active site of [FeFe]-hydrogenases can provide helpful hints for elucidating the mechanism of H2 evolution and uptake at the [FeFe]-hydrogenase active site and for designing bioinspired catalysts to replace the expensive noble metal catalysts for H2 generation and uptake. This perspective focuses on the recent progress in the formation and reactivity of iron hydrides closely related to the processes of proton reduction and hydrogen oxidation mediated by diiron dithiolate complexes. The second section surveys the bridging and terminal hydride species formed from various diiron complexes as well as the intramolecular proton transfer. The very recent progress in H2 activation by diiron dithiolate models are reviewed in the third section. In the concluding remarks and outlook, the differences in structure and catalytic mechanism between the synthetic models and the native [FeFe]-H2ase active site are compared and analyzed, which may cause the need for a significantly larger driving force and may lead to lower activities of synthetic models than the [FeFe]-H2ases for H2 generation and uptake.

Synthetic Strategies for Variably Substituted Ruthenium–Imidazophenanthrolinium Complexes

“…Additionally, a very close spatial proximity of the N-substituents to the catalytic sphere could be observed. [22,24,25] For the efficient connection of the photo and the catalytic centers, well-designed bridging ligands are necessary. [26][27][28][29] Such linkage systems should consist of a polypyridyl scaffold on the one side to coordinate to the ruthenium core as the photo center and on the other side a NHC functionality for coordination to the catalytically active metal.…”

A computational mechanistic investigation of hydrogen production in water using the [RhIII(dmbpy)2Cl2]+/[RuII(bpy)3]2+/ascorbic acid photocatalytic system

“…1 In this context, efficient photocatalytic production of dihydrogen (H 2 ) under visible-light irradiation, which is believed to be a convenient clean energy carrier for the future, is an important goal. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Those operating efficiently in fully aqueous solution were rare and limited to noble-metal based catalysts (rhodium and platinum) [22][23][24][25][26][27] until 2012, when several examples with cobalt, [28][29][30][31][32][33][34][35][36][37][38][39][40][41] iron [42][43][44][45] and nickel-based 46 catalysts were reported. Numerous photocatalytic systems in literature exhibit high activity in organic media or in mixtures of aqueous/organic solvents.…”

Highly Robust Hydrogen Generation by Bioinspired Ir Complexes for Dehydrogenation of Formic Acid in Water: Experimental and Theoretical Mechanistic Investigations at Different pH

“…An important synergistic effect between the metal center and cooperating ligands in hydrogenases has inspired many chemists to explore such a catalyst design principle (Scheme 1b). [30][31][32][33] DuBois and Bullock et al have developed a series of complexes with a pendent amine mimicking the structure of [FeFe]-hydrogenase to catalyze various transformations. [34][35][36] Pincer complexes with non-innocent ligands have also shown outstanding catalytic activity in FA dehydrogenation in organic solvents.…”