First Generation Analogues of the Binuclear Site in the Fe-Only Hydrogenases:  Fe2(μ-SR)2(CO)4(CN)22-

Schmidt, Michael; Contakes, Stephen M.; Rauchfuss, Thomas B.

doi:10.1021/ja9924187

Cited by 291 publications

(190 citation statements)

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“…Recently, efforts toward new catalyst development have focused on electrocatalysts for proton reduction (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). In this regard, some cobaloxime catalysts derived from dimethylglyoxime are active electrocatalytically and operate at particularly low overpotentials (9,18,19).…”

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confidence: 99%

Cobalt-dithiolene complexes for the photocatalytic and electrocatalytic reduction of protons in aqueous solutions

McNamara

Han

Yin

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

276

267

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Artificial photosynthesis (AP) is a promising method of converting solar energy into fuel (H 2 ). Harnessing solar energy to generate H 2 from H + is a crucial process in systems for artificial photosynthesis. Widespread application of a device for AP would rely on the use of platinum-free catalysts due to the scarcity of noble metals. Here we report a series of cobalt dithiolene complexes that are exceptionally active for the catalytic reduction of protons in aqueous solvent mixtures. All catalysts perform visible-light-driven reduction of protons from water when paired with as the photosensitizer and ascorbic acid as the sacrificial donor. Photocatalysts with electron withdrawing groups exhibit the highest activity with turnovers up to 9,000 with respect to catalyst. The same complexes are also active electrocatalysts in 1∶1 acetonitrile/water. The electrocatalytic mechanism is proposed to be ECEC, where the Co dithiolene catalysts undergo rapid protonation once they are reduced to . Subsequent reduction and reaction with H + lead to H 2 formation. Cobalt dithiolene complexes thus represent a new group of active catalysts for the reduction of protons.

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confidence: 99%

Cobalt-dithiolene complexes for the photocatalytic and electrocatalytic reduction of protons in aqueous solutions

McNamara

Han

Yin

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

276

267

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“…1). It reacts with cyanide with complete regioselectivity in CN Ϫ ͞CO exchange, yielding one cyanide on each iron, (-pdt)[Fe(CO) 2 (CN)] 2 2Ϫ (36)(37)(38). The coordination geometry of the dinuclear model complexes is that of a binuclear unit consisting of two edge-bridged square pyramids.…”

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confidence: 99%

The organometallic active site of [Fe]hydrogenase: Models and entatic states

Darensbourg

Lyon

Zhao

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

270

201

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The simple organometallic, (-S2)Fe2(CO)6, serves as a precursor to synthetic analogues of the chemically rudimentary iron-only hydrogenase enzyme active site. The fundamental properties of the (-SCH 2CH2CH2S)[Fe(CO)3]2 compound, including structural mobility and regioselectivity in cyanide͞carbon monoxide substitution reactions, relate to the enzyme active site in the form of transition-state structures along reaction paths rather than ground-state structures. Even in the absence of protein-based active-site organization, the ground-state structural model complexes are shown to serve as hydrogenase enzyme reaction models, H 2 uptake and H2 production, with the input of photoor electrochemical energy, respectively.

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“…Particular emphasis has been placed on variations of L, especially tertiary phosphines [1][2][3], but also isocyanides [4,5], N-heterocyclic carbenes [6][7][8][9], and cyanide [10][11][12][13]. While much effort has focused on functionalizing the dithiolate ligand [14][15][16][17][18][19][20], relatively little work has examined the possibility of replacing the thiolates with other bridging groups [21].…”

Section: Fe Complexes; Metal Hydride; Hydrogenase; Electrocatalysismentioning

confidence: 99%

Extending the motif of the [FeFe]-hydrogenase active site models: Protonation of Fe2(NR)2(CO)6−L species

Volkers

Rauchfuss

2007

Journal of Inorganic Biochemistry

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Studies on diiron dithiolato complexes have proven fruitful for modeling the active site of the [FeFe]hydrogenases. Here we present a departure from the classical Fe 2 S 2 motif by examining the viability of Fe 2 N 2 butterfly compounds as functional models for the diiron active site of [FeFe]-hydrogenases. Derivatization of Fe 2 (BC)(CO) 6 (1, BC = benzo-[c]-cinnoline) with PMe 3 affords Fe 2 (BC) (CO) 4 (PMe 3 ) 2 , which subsequently undergoes protonation at the Fe-Fe bond. The hydride [(μ-H) Fe 2 (BC)(CO) 4 (PMe 3 ) 2 ]PF 6 was characterized crystallographically as the C 2v isomer. It represents a rare example of a hydrido diiron complex that exists as observable isomers, depending on the location of the phosphine ligands -diapical and apical-basal. This hydride catalyzes the electrochemical reduction of protons. Keywords Fe complexes; Metal hydride; Hydrogenase; ElectrocatalysisIn recent years, many compounds of the type Fe 2 (S-R) 2 (CO) 4 L 2 have been prepared and examined as structural and functional models for the active site of [FeFe]-hydrogenases. Particular emphasis has been placed on variations of L, especially tertiary phosphines [1][2][3], but also isocyanides [4,5], N-heterocyclic carbenes [6][7][8][9], and cyanide [10][11][12][13]. While much effort has focused on functionalizing the dithiolate ligand [14][15][16][17][18][19][20], relatively little work has examined the possibility of replacing the thiolates with other bridging groups [21]. Best and coworkers demonstrated that the corresponding phosphides Fe 2 (PR 2 ) 2 (CO) 6 and [Fe 2 (PR 2 ) 2 (CO) 6 H] − are effective catalysts for hydrogen evolution [22].Incentives for broadening the range of bridging ligands include changing the steric profile of the catalysts, altering the susceptibility of the bridge toward electrophilic attack (important since these catalysts function in acidic media), incorporating functionality, and manipulating the electronic character (basicity, E 1/2 ) of the metals. Naturally, a fundamental motivation for investigating new bridging ligands is to elucidate the elementary design rules that will lead to greater mechanistic insight and, ultimately, a deeper understanding of hydrogenogenesis.Approximately 15 nitrogenous bridges are known to link pairs of iron centers, giving complexes of the general formula Fe 2 (NR 1,2 ) 2 (CO) 6 (Scheme 1). Many of the complexes were first reported in the 1960s and 1970s in an era where the interactions of nitrene-forming reagents and metal carbonyls were first systematized. We selected one representative of this series, Fe 2 (BC)(CO) 6 [23][24][25][26] properties would test most demandingly the scope of the hydrogenase behavior of the Fe 2 (μ-X) 2 L n systems (L = CO, donor ligands). This report summarizes these results, which indeed demonstrate the prospect that many nitrogenous bridging ligands could be applied to the modeling of hydrogenases.Compound 1 was prepared using the original method, using Fe 3 (CO) 12 in place of Fe(CO) 5 [27]. As for other donor ligands [26,...

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First Generation Analogues of the Binuclear Site in the Fe-Only Hydrogenases: Fe₂(μ-SR)₂(CO)₄(CN)₂²^-

Cited by 291 publications

References 20 publications

Cobalt-dithiolene complexes for the photocatalytic and electrocatalytic reduction of protons in aqueous solutions

Cobalt-dithiolene complexes for the photocatalytic and electrocatalytic reduction of protons in aqueous solutions

The organometallic active site of [Fe]hydrogenase: Models and entatic states

Extending the motif of the [FeFe]-hydrogenase active site models: Protonation of Fe2(NR)2(CO)6−L species

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