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Kick AC, Weyhermüller T, Hölscher M, Kaeffer N, Leitner W. Understanding Ligand Effects on Bielectronic Transitions: Chemo- and Electroreduction of Rhodium Bis(Diphosphine) Complexes to Low Oxidation States. Angew Chem Int Ed Engl 2024; 63:e202408356. [PMID: 38842465 DOI: 10.1002/anie.202408356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 06/03/2024] [Accepted: 06/03/2024] [Indexed: 06/07/2024]
Abstract
Rhodium complexes in the -I and 0 oxidation states are of great potential interest in catalytic applications. In contrast to their rhodium +I congeners, however, the structural and electronic parameters governing their access and stability are far less understood. Herein, we investigate the two-electron reduction of a parameterized series of bis(diphosphine) Rh complexes [Rh(dxpy)2]NTf2 (x=P-substituent, y=alkanediyl bridging P atoms). Through (electro)reductions from the RhI parents, Rh-I d10-complexes were obtained and characterized spectroscopically, including 103Rh NMR data. The reductive steps convolute with structural rearrangements from square planar to tetrahedral coordination. We found that the extent of these reorganisations defines whether the first E0(RhI/0) and second E0(Rh0/-I) reduction potentials are normally ordered, leading to monoelectronic stepwise transitions, or inverted, giving bielectronic events. Reductionist approaches based on Hammett parameters or the P-Rh-P bite angles provide only partial correlations with the redox potentials. However, we identified the C-O stretch of analogue diphosphine complexes as an expedient computational parameter that enables these correlations through both electronic and geometric features, even in a predictive manner. Gaining control over two-electron reduction behaviors through rationalized ligand effects has potential impact beyond Rh complexes, for molecular and enzymatic metal sites commonly exhibiting bielectronic transitions.
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Affiliation(s)
- Anne-Christine Kick
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52074, Aachen
| | - Thomas Weyhermüller
- Department of Molecular Catalysis, Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470, Mülheim an der Ruhr
| | - Markus Hölscher
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52074, Aachen
| | - Nicolas Kaeffer
- Department of Molecular Catalysis, Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470, Mülheim an der Ruhr
| | - Walter Leitner
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52074, Aachen
- Department of Molecular Catalysis, Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470, Mülheim an der Ruhr
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2
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Bourrez M, Gloaguen F. Electrochemical reduction and protonation of a biomimetic diiron azadithiolate hexacarbonyl complex: Mechanistic insights. Bioelectrochemistry 2023; 153:108488. [PMID: 37329847 DOI: 10.1016/j.bioelechem.2023.108488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/07/2023] [Accepted: 06/08/2023] [Indexed: 06/19/2023]
Abstract
The electrochemical reduction and protonation of [Fe2(adtH)(CO)6] (1, adtH = SCH2N(H)CH2S) and [Fe2(pdt)(CO)6] (2, pdt = SCH2CH2CH2S) in the presence of moderately strong acid in acetonitrile was investigated by cyclic voltammetry (CV), focusing on the catalysis of hydrogen evolution reaction (HER) by a {2e-,2H+} pathway. The turnover frequencies at zero overpotential (TOF0) of the N-protonated product 1(H)+ and 2 for the HER were estimated from simulations of the catalytic CV responses at low acid concentration using a simple ECEC mechanism (two electrochemical and chemical steps). This approach confirmed that 1(H)+ is clearly a better catalyst than 2, pointing to a possible role of the protonable and biologically relevant adtH ligand in the enhancement of the catalytic performances. Density functional theory (DFT) calculations further suggested that, owing to a strong structural rearrangement in the course of the catalytic cycle, the HER catalysis by 1(H)+ only involves the iron center adjacent to the amine group in adtH and not the two iron centers as in 2. Since terminal hydride species (FeFe-H) are known to more easily undergo protonolyse to H2 than their bridging hydride isomers (Fe-H-Fe), this may explain here the enhanced activity of 1(H)+ over 2 for the HER.
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Affiliation(s)
- Marc Bourrez
- CNRS, Univ Brest, CEMCA UMR 6521, 6 av Le Gorgeu, F-29238 Brest, France
| | - Frederic Gloaguen
- CNRS, Univ Brest, CEMCA UMR 6521, 6 av Le Gorgeu, F-29238 Brest, France.
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3
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Galuzzi B, Mirarchi A, Viganò EL, De Gioia L, Damiani C, Arrigoni F. Machine Learning for Efficient Prediction of Protein Redox Potential: The Flavoproteins Case. J Chem Inf Model 2022; 62:4748-4759. [PMID: 36126254 PMCID: PMC9554915 DOI: 10.1021/acs.jcim.2c00858] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Indexed: 11/29/2022]
Abstract
Determining the redox potentials of protein cofactors and how they are influenced by their molecular neighborhoods is essential for basic research and many biotechnological applications, from biosensors and biocatalysis to bioremediation and bioelectronics. The laborious determination of redox potential with current experimental technologies pushes forward the need for computational approaches that can reliably predict it. Although current computational approaches based on quantum and molecular mechanics are accurate, their large computational costs hinder their usage. In this work, we explored the possibility of using more efficient QSPR models based on machine learning (ML) for the prediction of protein redox potential, as an alternative to classical approaches. As a proof of concept, we focused on flavoproteins, one of the most important families of enzymes directly involved in redox processes. To train and test different ML models, we retrieved a dataset of flavoproteins with a known midpoint redox potential (Em) and 3D structure. The features of interest, accounting for both short- and long-range effects of the protein matrix on the flavin cofactor, have been automatically extracted from each protein PDB file. Our best ML model (XGB) has a performance error below 1 kcal/mol (∼36 mV), comparing favorably to more sophisticated computational approaches. We also provided indications on the features that mostly affect the Em value, and when possible, we rationalized them on the basis of previous studies.
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Affiliation(s)
- Bruno
Giovanni Galuzzi
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
- SYSBIO
Centre of Systems Biology/ISBE.IT, Piazza della Scienza 2, 20126, Milan, Italy
| | - Antonio Mirarchi
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Edoardo Luca Viganò
- Istituto
di Ricerche Farmacologiche Mario Negri, Via Mario Negri 2, 20156 Milan, Italy
| | - Luca De Gioia
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Chiara Damiani
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
- SYSBIO
Centre of Systems Biology/ISBE.IT, Piazza della Scienza 2, 20126, Milan, Italy
| | - Federica Arrigoni
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
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4
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Mai Y, Balzen AK, Torres RK, Callahan MP, Colson AC. A Modular Strategy for Expanding Electron-Sink Capacity in Noncanonical Cluster Assemblies. Inorg Chem 2021; 60:17733-17743. [PMID: 34748324 PMCID: PMC8653162 DOI: 10.1021/acs.inorgchem.1c02373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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A modular synthetic
strategy is described whereby organometallic
complexes exhibiting considerable electron-sink capacity may be assembled
by using only a few simple molecular components. The Fe2(PPh2)2(CO)5 fragment was selected
as a common electroactive component and was assembled around aromatic
cores bearing one, two, or three isocyanide functional groups, with
the resultant complexes possessing electron-sink capacities of two,
four, and six electrons, respectively. The latter complex is noteworthy
in that its electron-sink capacity was found to rival that of large
multinuclear clusters (e.g., [Ni32C6(CO)36]6– and [Ni38Pt6(CO)48]6–), which are often considered as benchmarks
of electron-sink behavior. Moreover, the modular assembly bearing
three Fe2(PPh2)2(CO)5 fragments
was observed to undergo reduction to a hexaanionic state over a potential
window of about −1.4 to −2.1 V (vs Fc/Fc+), the relatively compressed range being attributed to potential
inversions operative during the addition of the second, fourth, and
sixth electrons. Such complexes may be designated noncanonical
clusters because they exhibit redox properties similar to
those of large multinuclear clusters yet lack the extensive network
of metal–metal bonds and the condensed metallic cores that
typify the latter. By use of a
modular synthetic strategy and relatively few
molecular components, organometallic complexes exhibiting considerable
electron-sink capacity have been characterized. Complexes bearing
one, two, or three Fe2(PPh2)2(CO)5 fragments bound to aromatic isocyanide cores were found to
possess electron-sink capacities of two, four, and six electrons,
respectively, the latter rivaling the electron-sink capacity of large
polynuclear cluster benchmarks.
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Affiliation(s)
- Yume Mai
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
| | - Alexandria K Balzen
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
| | - Rebecca K Torres
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
| | - Michael P Callahan
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
| | - Adam C Colson
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
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Yuly JL, Zhang P, Ru X, Terai K, Singh N, Beratan DN. Efficient and reversible electron bifurcation with either normal or inverted potentials at the bifurcating cofactor. Chem 2021. [DOI: 10.1016/j.chempr.2021.03.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Almazahreh LR, Arrigoni F, Abul-Futouh H, El-khateeb M, Görls H, Elleouet C, Schollhammer P, Bertini L, De Gioia L, Rudolph M, Zampella G, Weigand W. Proton Shuttle Mediated by (SCH 2) 2P═O Moiety in [FeFe]-Hydrogenase Mimics: Electrochemical and DFT Studies. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05563] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Laith R. Almazahreh
- ERCOSPLAN Ingenieurbüro Anlagentechnik GmbH Arnstädter Straße 28, 99096 Erfurt, Germany
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, Humboldt Str. 8, 07743 Jena, Germany
| | - Federica Arrigoni
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Hassan Abul-Futouh
- Department of Pharmacy, Al-Zaytoonah University of Jordan, P.O. Box 130 Amman 11733 Jordan
| | - Mohammad El-khateeb
- Chemistry Department, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Helmar Görls
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, Humboldt Str. 8, 07743 Jena, Germany
| | - Catherine Elleouet
- UMR CNRS 6521, Chimie, Electrochimie Moléculaires et Chimie Analytique, Université de Bretagne Occidentale, UFR Sciences et Techniques, Cs 93837, 29238 CEDEX 3 Brest, France
| | - Philippe Schollhammer
- UMR CNRS 6521, Chimie, Electrochimie Moléculaires et Chimie Analytique, Université de Bretagne Occidentale, UFR Sciences et Techniques, Cs 93837, 29238 CEDEX 3 Brest, France
| | - Luca Bertini
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Luca De Gioia
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Manfred Rudolph
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, Humboldt Str. 8, 07743 Jena, Germany
| | - Giuseppe Zampella
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Wolfgang Weigand
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, Humboldt Str. 8, 07743 Jena, Germany
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Arrigoni F, Zampella G, Zhang F, Kagalwala HN, Li QL, Woods TJ, Rauchfuss TB. Computational and Experimental Investigations of the Fe 2(μ-S 2)/Fe 2(μ-S) 2 Equilibrium. Inorg Chem 2021; 60:3917-3926. [PMID: 33650855 PMCID: PMC8100967 DOI: 10.1021/acs.inorgchem.0c03709] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Density functional theory (DFT) calculations on Fe2S2(CO)6-2n(PMe3)2n for n = 0, 1, and 2 reveal that the most electron-rich derivatives (n = 2) exist as diferrous disulfides lacking an S-S bond. The thermal interconversion of the FeII2(S)2 and FeI2(S2) valence isomers is symmetry-forbidden. Related electron-rich diiron complexes [Fe2S2(CN)2(CO)4]2- of an uncertain structure are implicated in the biosynthesis of [FeFe]-hydrogenases. Several efforts to synthesize electron-rich derivatives of Fe2(μ-S2)(CO)6 (1) are described. First, salts of iron persulfido cyanides [Fe2(μ-S2)(CO)5(CN)]- and [Fe2(μ-S2)(CN)(CO)4(PPh3)]- were prepared by the reactions of NaN(tms)2 with 1 and Fe2(μ-S2)(CO)5(PPh3), respectively. Alternative approaches to electron-rich diiron disulfides targeted Fe2(μ-S2)(CO)4(diphosphine). Whereas the preparation of Fe2(μ-S2)(CO)4(dppbz) was straightforward, that of Fe2(μ-S2)(CO)4(dppv) required an indirect route involving the oxidation of Fe2(μ-SH)2(CO)4(dppv) (dppbz = C6H4-1,2-(PPh2)2, dppv = cis-C2H2(PPh2)2). DFT calculations indicate that the oxidation of Fe2(μ-SH)2(CO)4(dppv) produces singlet diferrous disulfide Fe2(μ-S)2(CO)4(dppv), which is sufficiently long-lived as to be trapped by ethylene. The reaction of 1 and dppv mainly afforded Fe2(μ-SCH=CHPPh2)(μ-SPPh2)(CO)5, implicating a S-centered reaction.
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Affiliation(s)
- Federica Arrigoni
- Department of Biotechnology and Biosciences University of Milano-Bicocca Piazza della Scienza 2 20126-Milan, Italy
| | - Giuseppe Zampella
- Department of Biotechnology and Biosciences University of Milano-Bicocca Piazza della Scienza 2 20126-Milan, Italy
| | - Fanjun Zhang
- School of Chemical Sciences University of Illinois Urbana-Champaign, Champaign, Illinois 61801, United States
| | - Husain N Kagalwala
- School of Chemical Sciences University of Illinois Urbana-Champaign, Champaign, Illinois 61801, United States
| | - Qian-Li Li
- School of Chemical Sciences University of Illinois Urbana-Champaign, Champaign, Illinois 61801, United States
| | - Toby J Woods
- School of Chemical Sciences University of Illinois Urbana-Champaign, Champaign, Illinois 61801, United States
| | - Thomas B Rauchfuss
- School of Chemical Sciences University of Illinois Urbana-Champaign, Champaign, Illinois 61801, United States
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8
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The Photochemistry of Fe2(S2C3H6)(CO)6(µ-CO) and Its Oxidized Form, Two Simple [FeFe]-Hydrogenase CO-Inhibited Models. A DFT and TDDFT Investigation. INORGANICS 2021. [DOI: 10.3390/inorganics9020016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
FeIFeI Fe2(S2C3H6)(CO)6(µ-CO) (1a–CO) and its FeIFeII cationic species (2a+–CO) are the simplest model of the CO-inhibited [FeFe] hydrogenase active site, which is known to undergo CO photolysis within a temperature-dependent process whose products and mechanism are still a matter of debate. Using density functional theory (DFT) and time-dependent density functional theory (TDDFT) computations, the ground state and low-lying excited-state potential energy surfaces (PESs) of 1a–CO and 2a+–CO have been explored aimed at elucidating the dynamics of the CO photolysis yielding Fe2(S2C3H6)(CO)6 (1a) and [Fe2(S2C3H6)(CO)6]+ (2a+), two simple models of the catalytic site of the enzyme. Two main results came out from these investigations. First, a–CO and 2a+–CO are both bound with respect to any CO dissociation with the lowest free energy barriers around 10 kcal mol−1, suggesting that at least 2a+–CO may be synthesized. Second, focusing on the cationic form, we found at least two clear excited-state channels along the PESs of 2a+–CO that are unbound with respect to equatorial CO dissociation.
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