Oxidative Addition of Thioesters to Iron(0): Active-Site Models for Hmd, Nature’s Third Hydrogenase

Royer, Aaron M.; Rauchfuss, Thomas B.; Gray, Danielle L.

doi:10.1021/om9004059

Cited by 86 publications

(78 citation statements)

References 37 publications

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“…All chemicals were purchased locally and used as received unless otherwise stated. Fe 3 (CO) 12 was prepared from Fe(CO) 5 using the procedure described in the literatures [23,24].…”

Section: Materials and Instrumentsmentioning

confidence: 99%

Electrochemical investigation into the electron transfer mechanism of a diiron hexacarbonyl complex bearing a bridging naphthalene moiety

Qian

Wang

Zhong

et al. 2015

Electrochimica Acta

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“…All chemicals were purchased locally and used as received unless otherwise stated. Fe 3 (CO) 12 was prepared from Fe(CO) 5 using the procedure described in the literatures [23,24].…”

Section: Materials and Instrumentsmentioning

confidence: 99%

Electrochemical investigation into the electron transfer mechanism of a diiron hexacarbonyl complex bearing a bridging naphthalene moiety

Qian

Wang

Zhong

et al. 2015

Electrochimica Acta

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“…The uptake of 13 CO by the active site does not result in scrambling, a fact that possibly relates to rigidity of the Fe II site in the protein matrix. [4] Such a change in electrophilicity of a formally d 6 metal ion on ligand protonation has precedent.…”

Section: A C H T U N G T R E N N U N G (Pcy 3 )]mentioning

confidence: 99%

“…[10] Synthetic analogues recently developed for the [Fe]-H 2 ase include octahedral Fe II dicarbonyls that mimic the denatured state of Hmd. [4,11,12] The Rauchfuss group reported a hexacoordinate (PhS)(Ph 2 PC 6 H 4 C(=O))Fe(CO) 3 [13] which has the acyl carbonyl built in as analogue of the CO-inhibited state. [4] A rare example of a pentacoordinate, presumably Fe II dicarbonyl, is that of an (acetyl)Fe II complex derived from carbonylation of a 3-coordinate Fe-Me species reported from the Holland laboratory.…”

Section: Introductionmentioning

confidence: 99%

“…[14] Inspired by the report of Liaw, et al, [15] that pentacoordinate, 16-electron Fe II dicarbonyl complexes could be accessed in the presence of strong p-donor ligands such as the 2-amidothiophenolate dianion, we have developed a series of iron dicarbonyl complexes 4, 5 and 6. Herein, we report syntheses, electronic structures, and characterizations, including protonation-activated CO uptake and 12 CO/ 13 CO exchange, as influenced by the unique electronic makeup of the Fe(NS) unit.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of a Pentacoordinate Iron Dicarbonyl as Synthetic Analogue of the Hmd or Mono‐Iron Hydrogenase Active Site

Liu

Popescu

et al. 2010

Chemistry A European J

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Pentacoordinate iron dicarbonyls, (NS)Fe(CO)(2)P (NS=2-amidothiophenylate, P=PCy(3) (4), PPh(3), (5), and P(OEt)(3) (6)) were prepared as potential biomimetics of the active site of the mono-iron hydrogenase, [Fe]-H(2)ase. Full characterization including X-ray diffraction, density functional theory (DFT) computations, and Mössbauer studies for complexes 5 and 6 find that, despite similar infrared v(CO) pattern and absorption frequencies as the active site of the [Fe]-H(2)ase, the geometrical distortions towards trigonal bipyramidal, the negative isomer shift parameters, and the differences in CO-uptake reactivity are due to the "non-innocence" of the NS ligand. Ligand-based protonation with a strong acid, HBF(4).Et(2)O, interrupted the extensive pi-delocalization over Fe and NS ligand of complex 4 and switched on CO uptake (1 bar) to form a CO adduct, mer-[(H-NS)Fe(CO)(3)(PCy(3))](+) or 4(CO)-H(+). The extrinsic CO is reversibly removed on deprotonation with Et(3)N to regenerate complex 4. In a (13)CO atmosphere, concomitant CO uptake by 4-H(+) and exchange with intrinsic CO groups provide a facile route to (13)C-labeled 4(CO)-H(+) and, upon deprotonation, (13)C-labeled complex 4. DFT calculations show substantial Fe character in the LUMO of 4-H(+) typical of the d(6) Fe(II) in a regular square-pyramidal geometry. Thus, the Lewis acidity of 4-H(+) makes it amenable for CO binding, whereas the dianionic NS ligand renders the iron center of 4 insufficiently electrophilic and largely of Fe(I) character.

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“…[22,[28][29][30][31] For example, the geometry of the iron site of [Ph 2 PC 6 H 4 C(O)]Fe(SPh)(CO) 3 -is similar to that found in the proposed structure of CO-and cyanide-inhibited [Fe]-hydrogenase, respectively. [31] Recently, two model iron compounds of the FeGP cofactor containing a five-membered metallacycle with an acyl ligand were reported. [32,33] The infrared frequency of the model compounds is almost identical to those of the enzymes.…”

Section: Fegp Cofactor Model With An Acyl-carbon Ligandmentioning

confidence: 72%

Structure and Function of [Fe]‐Hydrogenase and its Iron–Guanylylpyridinol (FeGP) Cofactor

Shima

Ermler

2010

Eur J Inorg Chem

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Abstract[Fe]‐hydrogenase functions in the methanogenic pathway of hydrogenotrophic methanogenic archaea. It catalyzes thereversible reduction of methenyltetrahydromethanopterin (methenyl‐H4MPT+) with H2 to methylene‐H4MPT and a proton by transferring a hydride ion to the proR position of the C14a carbon atom of methylene‐H4MPT. This third type of hydrogenase contains a unique iron–guanylylpyridinol (FeGP) cofactor, in which the iron atom is ligated by one cysteine sulfur atom, two CO groups, one solvent molecule, and an sp2‐hybridized nitrogen atom and an acyl carbon atom from the pyridinol ring. Three globular folding units of this protein form two clefts that serve as substrate‐binding and active sites and that can be open or closed. Structural data are presented for the apoenzyme in a closed form, the holoenzyme (enzyme with the FeGP cofactor), the C176A holoenzyme, and the binary C176A holoenzyme‐methylene‐H4MPT complex in an open form. A closed and potentially active binary complex has been reliably modeled on the basis of the open binary complex and the closed apoenzyme. In this model, the iron center sits near the Re face of the imidazolidine ring of the substrate. The iron ligation site trans to the acyl carbon atom is next to the C14a carbon atom and is therefore considered to be the H2 binding site.

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Oxidative Addition of Thioesters to Iron(0): Active-Site Models for Hmd, Nature’s Third Hydrogenase

Cited by 86 publications

References 37 publications

Electrochemical investigation into the electron transfer mechanism of a diiron hexacarbonyl complex bearing a bridging naphthalene moiety

Electrochemical investigation into the electron transfer mechanism of a diiron hexacarbonyl complex bearing a bridging naphthalene moiety

Analysis of a Pentacoordinate Iron Dicarbonyl as Synthetic Analogue of the Hmd or Mono‐Iron Hydrogenase Active Site

Structure and Function of [Fe]‐Hydrogenase and its Iron–Guanylylpyridinol (FeGP) Cofactor

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