Hydrogen generation: Aromatic dithiolate-bridged metal carbonyl complexes as hydrogenase catalytic site models

Pandey, Indresh Kumar; Natarajan, Mookan; Kaur‐Ghumaan, Sandeep

doi:10.1016/j.jinorgbio.2014.11.006

Cited by 49 publications

(14 citation statements)

References 222 publications

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“…Selected structural parameters are presented in Table 2. The Fe-Fe bond length is close to that reported for the active site of the hydrogenase enzyme (2.6 Å ) and similar models (Peters et al, 1998;Nicolet et al, 1999;Pandey et al, 2008;Li & Rauchfuss;Haley et al, 2016;Mebi et al, 2012;Pandey et al, 2015). The Fe-S bond linked to the axial naphthalene group is slightly longer, by $0.01 Å , than that linked to the equatorial naphthalene group.…”

Section: Figuresupporting

confidence: 83%

Crystal and electronic structure of a hexacarbonyldiiron cluster tethered to naphthalene-2-thiolate ligands

2018

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The structure of the previously reported complex bis(μ-naphthalene-2-thiolato-κS:S)bis(tricarbonyliron)(Fe-Fe), [Fe(CHS)(CO)], has been characterized by X-ray diffraction. In the solid state, the dinuclear complex adopts a butterfly-like shape, with an equatorial-axial spatial orientation of the naphthalene groups covalently coupled to the [SFe(CO)] unit. The asymmetric unit contains three independent [(μ-naphthalene-2-thiolato)Fe(CO)] molecules. These molecules show intermolecular π-π stacking interactions between the naphthalene rings, which was confirmed by Hirshfield surface analysis. The electronic spectrum of the complex recorded in acetonitrile shows a band centered at 350 nm (ℇ = 4.6 × 10 M cm) and tailing into the visible region. This absorption can be attributed to a π→π* electronic transition within the naphthalene moiety and a metal-based d→d transition.

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Section: Figuresupporting

confidence: 83%

Crystal and electronic structure of a hexacarbonyldiiron cluster tethered to naphthalene-2-thiolate ligands

2018

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“…Notably, the ΔΔG calculated for 19 is more negative than for 18, suggesting a role for the aromatic linker in the PI process. Indeed, similarly to Fe 2 S 2 analogues, [70,76] the presence of the sp 2 carbon atoms of the aromatic portion reduces the negative charge on P, making it a better leaving group. The analysis of NBO charges in 19 2À and 18 2À confirms this hypothesis; partial charges on the P atoms in 19 2À are 0.74 and 0.25 (on bridging and uncoordinated P atoms, respectively), and become 0.64 and 0.29 in 18 2À .…”

Section: Resultsmentioning

confidence: 99%

Rational Design of Fe₂(μ‐PR₂)₂(L)₆ Coordination Compounds Featuring Tailored Potential Inversion

et al. 2020

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It was recently discovered that some redox proteins can thermodynamically and spatially split two incoming electrons towards different pathways, resulting in the one-electron reduction of two different substrates, featuring reduction potential respectively higher and lower than the parent reductant. This energy conversion process, referred to as electron bifurcation, is relevant not only from a biochemical perspective, but also for the groundbreaking applications that electron-bifurcating molecular devices could have in the field of energy conversion. Natural electron-bifurcating systems contain a two-electron redox centre featuring potential inversion (PI), i. e. with second reduction easier than the first. With the aim of revealing key factors to tailor the span between first and second redox potentials, we performed a systematic density functional study of a 26-molecule set of models with the general formula Fe 2 (μ-PR 2) 2 (L) 6. It turned out that specific features such as i) a FeÀ Fe antibonding character of the LUMO, ii) presence of electrondonor groups and iii) low steric congestion in the Fe's coordination sphere, are key ingredients for PI. In particular, the synergic effects of i)-iii) can lead to a span between first and second redox potentials larger than 700 mV. More generally, the "molecular recipes" herein described are expected to inspire the synthesis of Fe 2 P 2 systems with tailored PI, of primary relevance to the design of electron-bifurcating molecular devices.

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“…The active site consists of a diiron core with two Fe‐S‐Fe bridges; the sulfur atoms are connected by an organic linker . Since the discovery that the (μ‐pdt)[Fe(CO) 3 ] 2 complex (pdt=propanedithiolate) reproduces several features of the [FeFe]‐H 2 ase diiron core, biomimetics of this active site continue to be developed and studied . These model complexes allow access to a large number of structural variants with different S‐to‐S linkers and ligands around the metal center.…”

Section: Introductionmentioning

confidence: 99%

“…[12][13][14] Sincet he discovery that the (m-pdt)[Fe(CO) 3 ] 2 complex (pdt = propanedithiolate) [15] reproduces severalf eatures of the [FeFe]-H 2 ase diiron core, biomimetics of this active site continue to be developed and studied. [10,16,17] These model complexes allow access to al arge number of structuralv ariants with different S-to-S linkers and ligandsa round the metalc enter.B ecause some of these have been shown to have catalytic activity when an open site is generated, or when CO ligandsa re replaced by others oft donors, there is considerable interest in understanding the re-activity of the iron-ligand bonds in these systems. For example, several studies have focusedo nt he kinetics and mechanism of thermal CO displacementf rom the hexacarbonyl complex with different mercapto bridges.…”

Section: Introductionmentioning

confidence: 99%

Ligand Displacement Reaction Paths in a Diiron Hydrogenase Active Site Model Complex

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Moncho

Lunsford

et al. 2016

Chemistry A European J

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The mechanism and energetics of CO, 1-hexene, and 1-hexyne substitution from the complexes (SBenz)2 [Fe2 (CO)6 ] (SBenz=SCH2 Ph) (1-CO), (SBenz)2 [Fe2 (CO)5 (η(2) -1-hexene)] (1-(η(2) -1-hexene)), and (SBenz)2 [Fe2 (CO)5 (η(2) -1-hexyne)] (1-(η(2) -1-hexyne)) were studied by using time-resolved infrared spectroscopy. Exchange of both CO and 1-hexyne by P(OEt)3 and pyridine, respectively, proceeds by a bimolecular mechanism. As similar activation enthalpies are obtained for both reactions, the rate-determining step in both cases is assumed to be the rotation of the Fe(CO)2 L (L=CO or 1-hexyne) unit to accommodate the incoming ligand. The kinetic profile for the displacement of 1-hexene is quite different than that for the alkyne and, in this case, both reaction channels, that is, dissociative (SN 1) and associative (SN 2), were found to be competitive. Because DFT calculations predict similar binding enthalpies of alkene and alkyne to the iron center, the results indicate that the bimolecular pathway in the case of the alkyne is lower in free energy than that of the alkene. In complexes of this type, subtle changes in the departing ligand characteristics and the nature of the mercapto bridge can influence the exchange mechanism, such that more than one reaction pathway is available for ligand substitution. The difference between this and the analogous study of (μ-pdt)[Fe(CO)3 ]2 (pdt=S(CH2 )3 S) underscores the unique characteristics of a three-atom S-S linker in the active site of diiron hydrogenases.

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Hydrogen generation: Aromatic dithiolate-bridged metal carbonyl complexes as hydrogenase catalytic site models

Cited by 49 publications

References 222 publications

Crystal and electronic structure of a hexacarbonyldiiron cluster tethered to naphthalene-2-thiolate ligands

Crystal and electronic structure of a hexacarbonyldiiron cluster tethered to naphthalene-2-thiolate ligands

Rational Design of Fe₂(μ‐PR₂)₂(L)₆ Coordination Compounds Featuring Tailored Potential Inversion

Ligand Displacement Reaction Paths in a Diiron Hydrogenase Active Site Model Complex

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Hydrogen generation: Aromatic dithiolate-bridged metal carbonyl complexes as hydrogenase catalytic site models

Cited by 49 publications

References 222 publications

Crystal and electronic structure of a hexacarbonyldiiron cluster tethered to naphthalene-2-thiolate ligands

Crystal and electronic structure of a hexacarbonyldiiron cluster tethered to naphthalene-2-thiolate ligands

Rational Design of Fe2(μ‐PR2)2(L)6 Coordination Compounds Featuring Tailored Potential Inversion

Ligand Displacement Reaction Paths in a Diiron Hydrogenase Active Site Model Complex

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Rational Design of Fe₂(μ‐PR₂)₂(L)₆ Coordination Compounds Featuring Tailored Potential Inversion