Synthesis of the H-cluster framework of iron-only hydrogenase

Tard, Cédric; Liu, Xiaoming; Ibrahim, Saad K.; Bruschi, Maurizio; Gioia, Luca De; Davies, Siân C.; Yang, Xin; Wang, Lai-Sheng; Sawers, R. Gary; Pickett, Christopher J.

doi:10.1038/nature03298

Cited by 492 publications

(427 citation statements)

References 28 publications

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“…Examples of molybdenum-and iron-based catalysts have also been reported. [14][15][16] Significant advances have been realized with iron-thiolate complexes of the type [Fe 2 (m-SRS)(CO) 6Àx L x ] (R= organic group, L = electron-donor ligand, x 4), [17][18][19][20][21][22][23][24][25] which are simplified models of the Fe 2 S 2 subunit of iron-iron hydrogenase enzymes. [26] The utilization of these iron-thiolate complexes for visible light-driven H 2 production has been recently reviewed.…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic Hydrogen Production Using Models of the Iron–Iron Hydrogenase Active Site Dispersed in Micellar Solution

2013

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International audienceIron–thiolate complexes of the type [Fe2(μ-bdt)(CO)6−xP(OMe3)x] (bdt=S2C6H4=benzenedithiolate, x≤2) are simplified models of iron–iron hydrogenase enzymes. Recently, we have shown that these water-insoluble organometallic complexes, when included into micelles formed by sodium dodecyl sulfate (SDS), are good catalysts for the electrochemical production of hydrogen in aqueous solutions at pH<6. We herein report that the all-CO derivative [Fe2(μ-bdt)(CO)6] (1), owing to its comparatively low reduction potential, is also a robust molecular catalyst for visible-light-driven production of H2 in aqueous SDS solutions at pH 10.5. Irradiation at λ=455 nm of a system consisting of complex 1, Eosin Y as a sensitizer, and triethylamine as an electron donor produced up to 0.86 mL of H2 in 4.5 h, corresponding to a turnover number of 117 mol of H2 per mol of catalyst. In the presence of a large excess of sensitizer, the production of H2 lasted for more than 30 h, stressing the relative stability of complex 1 under the photocatalytic conditions used herein. Thermodynamic considerations and UV/Vis spectroscopy experiments suggest that the catalytic cycle begins with the photo-driven reduction of complex 1. The reduced intermediate reacts with a proton source to yield iron hydride. Subsequent reduction and protonation steps produce H2, regenerating the starting complex. As a result, the iron–thiolate complex 1 is a versatile proton reduction catalyst that can utilize either solar or electrical energy inputs, providing a starting point for the construction of noble metal-free molecular systems for renewable H2 production

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Section: Introductionmentioning

confidence: 99%

Photocatalytic Hydrogen Production Using Models of the Iron–Iron Hydrogenase Active Site Dispersed in Micellar Solution

2013

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“…As the +Fe-N-O of the free (bmedach)Fe(NO) metallodithiolate ligand is 148(2)°, this metric suggests that the electron density drained from the Fe(NO) unit via the bridging thiolates in 1 red is less than that in 1 þ ; that is, the nitrosyls act in concert to accommodate the redox level that is largely changing within the Fe(NO) 2 unit. Attempts to further reduce 1 red using stronger reductants such as KC 8 or Na þ (benzophenone À ) resulted in decomposition and rearrangement with the only identifiable product being reduced Roussin's red ester (see Supplementary Methods for details) 18 .…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…Biochemical studies have shown that the redox active 4Fe4S cluster that is directly attached to the 2Fe subsite is required for the extraordinary activity of the enzyme. However, intricate molecular constructions with exogeneous redox active centres attached to the diiron unit that mimic the structure of the full H-cluster suffer from instability and low activity 8 . Full catalytic activity for proton reduction approaching the efficiency of the enzyme has only been achieved in hybrid constructs where the synthetic model (m-(SCH 2 ) 2 NH)[Fe(CO) 2 (CN)] 2 2 À has been inserted into the apo-[FeFe]-H 2 ase protein 9,10 .…”

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confidence: 99%

Redox active iron nitrosyl units in proton reduction electrocatalysis

et al. 2014

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Base metal, molecular catalysts for the fundamental process of conversion of protons and electrons to dihydrogen, remain a substantial synthetic goal related to a sustainable energy future. Here we report a diiron complex with bridging thiolates in the butterfly shape of the 2Fe2S core of the [FeFe]-hydrogenase active site but with nitrosyl rather than carbonyl or cyanide ligands. This binuclear [(NO)Fe(N 2 S 2 )Fe(NO) 2 ] þ complex maintains structural integrity in two redox levels; it consists of a (N 2 S 2 )Fe(NO) complex (N 2 S 2 ¼ N,N 0 -bis(2-mercaptoethyl)-1,4-diazacycloheptane) that serves as redox active metallodithiolato bidentate ligand to a redox active dinitrosyl iron unit, Fe(NO) 2 . Experimental and theoretical methods demonstrate the accommodation of redox levels in both components of the complex, each involving electronically versatile nitrosyl ligands. An interplay of orbital mixing between the Fe(NO) and Fe(NO) 2 sites and within the iron nitrosyl bonds in each moiety is revealed, accounting for the interactions that facilitate electron uptake, storage and proton reduction.

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“…Platinum is very efficient in catalyzing H 2 production, but the low natural abundance and high cost of this noble metal restrict its widespread utilization 9, 10. Progress has been made in identifying HER catalysts by the use of molecular complexes consisting of earth‐abundant metals, such as Fe,11, 12, 13, 14, 15 Co,9, 16, 17, 18, 19, 20 Ni,21, 22, 23, 24, 25 and Mo 26, 27. For example, Co and Fe complexes of N‐based macrocyclic ligands (e.g.…”

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confidence: 99%

Singly versus Doubly Reduced Nickel Porphyrins for Proton Reduction: Experimental and Theoretical Evidence for a Homolytic Hydrogen‐Evolution Reaction

et al. 2016

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A nickel(II) porphyrin Ni‐P (P=porphyrin) bearing four meso‐C6F5 groups to improve solubility and activity was used to explore different hydrogen‐evolution‐reaction (HER) mechanisms. Doubly reduced Ni‐P ([Ni‐P]2−) was involved in H2 production from acetic acid, whereas a singly reduced species ([Ni‐P]−) initiated HER with stronger trifluoroacetic acid (TFA). High activity and stability of Ni‐P were observed in catalysis, with a remarkable i c/i p value of 77 with TFA at a scan rate of 100 mV s−1 and 20 °C. Electrochemical, stopped‐flow, and theoretical studies indicated that a hydride species [H‐Ni‐P] is formed by oxidative protonation of [Ni‐P]−. Subsequent rapid bimetallic homolysis to give H2 and Ni‐P is probably involved in the catalytic cycle. HER cycling through this one‐electron‐reduction and homolysis mechanism has been proposed previously but rarely validated. The present results could thus have broad implications for the design of new exquisite cycles for H2 generation.

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Synthesis of the H-cluster framework of iron-only hydrogenase

Cited by 492 publications

References 28 publications

Photocatalytic Hydrogen Production Using Models of the Iron–Iron Hydrogenase Active Site Dispersed in Micellar Solution

Photocatalytic Hydrogen Production Using Models of the Iron–Iron Hydrogenase Active Site Dispersed in Micellar Solution

Redox active iron nitrosyl units in proton reduction electrocatalysis

Singly versus Doubly Reduced Nickel Porphyrins for Proton Reduction: Experimental and Theoretical Evidence for a Homolytic Hydrogen‐Evolution Reaction

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