Small molecule mimics of hydrogenases: hydrides and redox

Gloaguen, Frédéric; Rauchfuss, Thomas B.

doi:10.1039/b801796b

Cited by 621 publications

(474 citation statements)

References 66 publications

(89 reference statements)

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“…3,11,12 Although the natural enzyme features iron centers in square pyramidal environments that are inverted relative to each other such that a terminal open coordination site is available, the irons in most of these model complexes are in the so-called "eclipsed" geometry in which the two pyramids have the same orientation. Complexes with an "inverted" iron center, although known, remain the exception.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

et al. 2014

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Abstract:Two pentacoordinate mononuclear iron carbonyls of the form (bdt)Fe(CO)P 2 [bdt = benzene-1,2-dithiolate; P 2 = 1,1'-diphenylphosphinoferrocene (1) or methyl-2-{bis(diphenylphosphinomethyl)amino}acetate (2)] were prepared as functional, biomimetic models for the distal iron (Fe d ) of the active site of [FeFe]-hydrogenase. Xray crystal structures of the complexes reveal that, despite similar ν(CO) stretching band frequencies, the two complexes have different coordination geometries. In X-ray crystal structures, the iron center of 1 is in a distorted trigonal bipyramidal arrangement, and that of 2 is in a distorted square pyramidal geometry. Electrochemical investigation shows that both complexes catalyze electrochemical proton reduction from acetic acid at mild overpotential, 0.17 and 0.38 V for 1 and 2, respectively. Although coordinatively unsaturated, the complexes display only weak, reversible binding affinity towards CO(1 bar). However, ligand centered protonation by the strong acid, HBF 4 .OEt 2 , triggers quantitative CO uptake by 1 to form a dicarbonyl analogue [1(H)-CO] + that can be reversibly converted back to 1 by deprotonation using NEt 3 . Both crystallographically determined distances within the bdt ligand and DFT calculations suggest that the iron centers in both 1 and 2 are partially reduced at the expense of partial oxidation of the bdt ligand. Ligand protonation interrupts this extensive electronic delocalization between the Fe and bdt making 1(H) + susceptible to external CO binding.3

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Section: Introductionmentioning

confidence: 99%

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

et al. 2014

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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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“…1 In recent years, it has been shown that many synthetic compounds based loosely on the active site structure of these enzymes also have the ability to produce hydrogen. [2][3][4][5][6][7][8][9] These iron-or nickel-based mimics are particularly attractive as they offer the possibility of replacing the platinum-based systems currently in technological use with more economically-viable materials.…”

Section: Supporting Information Placeholdermentioning

confidence: 99%

Investigation of the Ultrafast Dynamics Occurring during Unsensitized Photocatalytic H₂ Evolution by an [FeFe]-Hydrogenase Subsite Analogue

et al. 2014

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Small molecule mimics of hydrogenases: hydrides and redox

Cited by 621 publications

References 66 publications

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

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

Investigation of the Ultrafast Dynamics Occurring during Unsensitized Photocatalytic H₂ Evolution by an [FeFe]-Hydrogenase Subsite Analogue

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Small molecule mimics of hydrogenases: hydrides and redox

Cited by 621 publications

References 66 publications

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

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

Investigation of the Ultrafast Dynamics Occurring during Unsensitized Photocatalytic H2 Evolution by an [FeFe]-Hydrogenase Subsite Analogue

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Investigation of the Ultrafast Dynamics Occurring during Unsensitized Photocatalytic H₂ Evolution by an [FeFe]-Hydrogenase Subsite Analogue