Combined Spectroscopic/Computational Study of Binuclear Fe(I)-Fe(I) Complexes: Implications for the Fully-Reduced Active-Site Cluster of Fe-Only Hydrogenases.
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| Title: | Combined Spectroscopic/Computational Study of Binuclear Fe(I)-Fe(I) Complexes: Implications for the Fully-Reduced Active-Site Cluster of Fe-Only Hydrogenases. |
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| Authors: | Fiedler, Adam T.1, Brunold, Thomas C.1 brunold@chem.wisc.edu |
| Source: | Inorganic Chemistry. 3/21/2005, Vol. 44 Issue 6, p1794-1809. 16p. 7 Diagrams, 6 Charts, 15 Graphs. |
| Subjects: | Iron compounds, Hydrogenase, Oxidoreductases, Inorganic compounds, Inorganic chemistry, Chemistry |
| Abstract: | The Fe(I)-Fe(I) dimer complex [Fe2(pdt)(CO)4(CN)2][Et4N]2 (2), where pdt -- 1,3-propane dithiolate, serves as a model of the fully reduced [2Fe]H component of the H cluster, which is the active site for catalysis in Fe-only hydrogenases (FeHases). Electronic absorption, magnetic circular dichroism (MCD), and resonance Raman (rR) spectroscopies have been employed to characterize both the ground and excited states of 2 as well as those of the related complex Fe2(pdt)(CO)6 (1). These results have been combined with density functional theory (DFT) computations to produce experimentally validated bonding descriptions of 1 and 2. It is shown that Fe(I)-S covalency is significantly reduced upon dicyano substitution (i.e., conversion of 1 → 2), while the corresponding Fe(I)-CO/ CN π-backbonding interactions are strengthened, results that are corroborated by normal-coordinate analyses of the vibrational data. Detailed assignments of the features observed in the electronic absorption spectra of 1 and 2 have been developed on the basis of time-dependent DFT (TD-DFT) calculations, which provide remarkably accurate simulations of the experimental data. For both complexes, all bands below 32 000 cm-1 arise from transitions involving electronic excitation within the binuclear Fe-Fe core, with the most intense feature assigned to the Fe(σb) → Fe(σ*) transition. Analysis of the corresponding rR excitation profiles within the framework of time-dependent Heller theory reveals that in each case the Fe-Fe bond is elongated by ∼0.3 &ARing; in the Fe(σb) → Fe(σ*) excited state. Finally, building upon the insights gained from the spectroscopic/computational studies of 1 and 2, our computational methodology has been extended to the reduced enzyme active site, providing insights into the electronic structure of the [2Fe]H subcluster in the Hred state and its relationship to catalysis. [ABSTRACT FROM AUTHOR] |
| Copyright of Inorganic Chemistry is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Items | – Name: Title Label: Title Group: Ti Data: Combined Spectroscopic/Computational Study of Binuclear Fe(I)-Fe(I) Complexes: Implications for the Fully-Reduced Active-Site Cluster of Fe-Only Hydrogenases. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Fiedler%2C+Adam+T%2E%22">Fiedler, Adam T.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Brunold%2C+Thomas+C%2E%22">Brunold, Thomas C.</searchLink><relatesTo>1</relatesTo><i> brunold@chem.wisc.edu</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Inorganic+Chemistry%22">Inorganic Chemistry</searchLink>. 3/21/2005, Vol. 44 Issue 6, p1794-1809. 16p. 7 Diagrams, 6 Charts, 15 Graphs. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Iron+compounds%22">Iron compounds</searchLink><br /><searchLink fieldCode="DE" term="%22Hydrogenase%22">Hydrogenase</searchLink><br /><searchLink fieldCode="DE" term="%22Oxidoreductases%22">Oxidoreductases</searchLink><br /><searchLink fieldCode="DE" term="%22Inorganic+compounds%22">Inorganic compounds</searchLink><br /><searchLink fieldCode="DE" term="%22Inorganic+chemistry%22">Inorganic chemistry</searchLink><br /><searchLink fieldCode="DE" term="%22Chemistry%22">Chemistry</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: The Fe(I)-Fe(I) dimer complex [Fe2(pdt)(CO)4(CN)2][Et4N]2 (2), where pdt -- 1,3-propane dithiolate, serves as a model of the fully reduced [2Fe]H component of the H cluster, which is the active site for catalysis in Fe-only hydrogenases (FeHases). Electronic absorption, magnetic circular dichroism (MCD), and resonance Raman (rR) spectroscopies have been employed to characterize both the ground and excited states of 2 as well as those of the related complex Fe2(pdt)(CO)6 (1). These results have been combined with density functional theory (DFT) computations to produce experimentally validated bonding descriptions of 1 and 2. It is shown that Fe(I)-S covalency is significantly reduced upon dicyano substitution (i.e., conversion of 1 → 2), while the corresponding Fe(I)-CO/ CN π-backbonding interactions are strengthened, results that are corroborated by normal-coordinate analyses of the vibrational data. Detailed assignments of the features observed in the electronic absorption spectra of 1 and 2 have been developed on the basis of time-dependent DFT (TD-DFT) calculations, which provide remarkably accurate simulations of the experimental data. For both complexes, all bands below 32 000 cm-1 arise from transitions involving electronic excitation within the binuclear Fe-Fe core, with the most intense feature assigned to the Fe(σb) → Fe(σ*) transition. Analysis of the corresponding rR excitation profiles within the framework of time-dependent Heller theory reveals that in each case the Fe-Fe bond is elongated by ∼0.3 &ARing; in the Fe(σb) → Fe(σ*) excited state. Finally, building upon the insights gained from the spectroscopic/computational studies of 1 and 2, our computational methodology has been extended to the reduced enzyme active site, providing insights into the electronic structure of the [2Fe]H subcluster in the Hred state and its relationship to catalysis. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Inorganic Chemistry is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1021/ic048739n Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 16 StartPage: 1794 Subjects: – SubjectFull: Iron compounds Type: general – SubjectFull: Hydrogenase Type: general – SubjectFull: Oxidoreductases Type: general – SubjectFull: Inorganic compounds Type: general – SubjectFull: Inorganic chemistry Type: general – SubjectFull: Chemistry Type: general Titles: – TitleFull: Combined Spectroscopic/Computational Study of Binuclear Fe(I)-Fe(I) Complexes: Implications for the Fully-Reduced Active-Site Cluster of Fe-Only Hydrogenases. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Fiedler, Adam T. – PersonEntity: Name: NameFull: Brunold, Thomas C. IsPartOfRelationships: – BibEntity: Dates: – D: 21 M: 03 Text: 3/21/2005 Type: published Y: 2005 Identifiers: – Type: issn-print Value: 00201669 Numbering: – Type: volume Value: 44 – Type: issue Value: 6 Titles: – TitleFull: Inorganic Chemistry Type: main |
| ResultId | 1 |
