A di-iron dithiolate possessing structural elements of the carbonyl/cyanide sub-site of the H-centre of Fe-only hydrogenase

Cloirec, Alban Le; Davies, Siân C.; Evans, David; Hughes, David L.; Pickett, C. J.; Best, Stephen P.; Borg, Stacey J.

doi:10.1039/a906391i

Cited by 265 publications

(177 citation statements)

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“…The active site of [FeFe]-hydrogenase, referred to as the H-cluster, contains a dinuclear iron cluster with CO and CN − ligands, known as [2Fe] H cluster, to which a Fe 4 S 4 cubane is attached by the sulphur atom of a cysteine residue (Figure 1). In the last decade, many experimental and quantum chemical studies focussed on their structures and redox properties, and much progress has been made regarding the elucidation of the reaction mechanism [11][12][13][14][15][16][17][18][19][20][21][22][23]. For example, mechanisms for heterolytic cleavage of bound H 2 have been studied, based either on a transient formation of a terminal or on a bridging hydride isomer [11,[24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Targeting Intermediates of [FeFe]-Hydrogenase by CO and CN Vibrational Signatures

Greco

Bruschi

et al. 2011

Inorg. Chem.

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In this work we employ density functional theory to assign vibrational signatures of [FeFe]-hydrogenase intermediates to molecular structures. For this purpose, we perform an exhaustive analysis of structures and harmonic vibrations of a series of CN and CO containing model clusters of the [FeFe]-hydrogenase enzyme active site considering also different charges, counter ions and solvents. The pure density functional BP86 in combination with a triple-zeta polarized basis set produce reliable molecular structures as well as harmonic vibrations. Calculated CN and CO stretching vibrations are analyzed separately. Our results are discussed in close comparison to previous studies. Finally, we apply the scaled vibrational frequencies to assign intermediates in [FeFe]-hydrogenase's reaction cycle.

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Section: Introductionmentioning

confidence: 99%

Targeting Intermediates of [FeFe]-Hydrogenase by CO and CN Vibrational Signatures

Greco

Bruschi

et al. 2011

Inorg. Chem.

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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.

271

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%

“…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 [26,28], PMe 3 displaced two of the CO ligands in 1 to afford the red-colored Fe 2 (BC)(CO) 4 (PMe 3 ) 2 (2) (Eq.…”

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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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A di-iron dithiolate possessing structural elements of the carbonyl/cyanide sub-site of the H-centre of Fe-only hydrogenase

Cited by 265 publications

References 3 publications

Targeting Intermediates of [FeFe]-Hydrogenase by CO and CN Vibrational Signatures

Targeting Intermediates of [FeFe]-Hydrogenase by CO and CN Vibrational Signatures

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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