1
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Hooper RX, Wertz AE, Shafaat HS, Holland PL. Evaluating Diazene to N 2 Interconversion at Iron-Sulfur Complexes. Chemistry 2024; 30:e202304072. [PMID: 38376370 PMCID: PMC11045311 DOI: 10.1002/chem.202304072] [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: 12/06/2023] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 02/21/2024]
Abstract
Biological N2 reduction occurs at sulfur-rich multiiron sites, and an interesting potential pathway is concerted double reduction/ protonation of bridging N2 through PCET. Here, we test the feasibility of using synthetic sulfur-supported diiron complexes to mimic this pathway. Oxidative proton transfer from μ-η1 : η1-diazene (HN=NH) is the microscopic reverse of the proposed N2 fixation pathway, revealing the energetics of the process. Previously, Sellmann assigned the purple metastable product from two-electron oxidation of [{Fe2+(PPr3)L1}2(μ-η1 : η1-N2H2)] (L1=tetradentate SSSS ligand) at -78 °C as [{Fe2+(PPr3)L1}2(μ-η1 : η1-N2)]2+, which would come from double PCET from diazene to sulfur atoms of the supporting ligands. Using resonance Raman, Mössbauer, NMR, and EPR spectroscopies in conjunction with DFT calculations, we show that the product is not an N2 complex. Instead, the data are most consistent with the spectroscopically observed species being the mononuclear iron(III) diazene complex [{Fe(PPr3)L1}(η2-N2H2)]+. Calculations indicate that the proposed double PCET has a barrier that is too high for proton transfer at the reaction temperature. Also, PCET from the bridging diazene is highly exergonic as a result of the high Fe3+/2+ redox potential, indicating that the reverse N2 protonation would be too endergonic to proceed. This system establishes the "ground rules" for designing reversible N2/N2H2 interconversion through PCET, such as tuning the redox potentials of the metal sites.
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Affiliation(s)
- Reagan X Hooper
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT-06511
| | - Ashlee E Wertz
- Department of Chemistry and Biochemistry, The Ohio State University, 100 W 18th Ave, Columbus, OH-43210
| | - Hannah S Shafaat
- Department of Chemistry and Biochemistry, The Ohio State University, 100 W 18th Ave, Columbus, OH-43210
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA-90095
| | - Patrick L Holland
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT-06511
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2
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Nitrogen reduction by the Fe sites of synthetic [Mo 3S 4Fe] cubes. Nature 2022; 607:86-90. [PMID: 35794270 DOI: 10.1038/s41586-022-04848-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 05/09/2022] [Indexed: 11/08/2022]
Abstract
Nitrogen (N2) fixation by nature, which is a crucial process for the supply of bio-available forms of nitrogen, is performed by nitrogenase. This enzyme uses a unique transition-metal-sulfur-carbon cluster as its active-site co-factor ([(R-homocitrate)MoFe7S9C], FeMoco)1,2, and the sulfur-surrounded iron (Fe) atoms have been postulated to capture and reduce N2 (refs. 3-6). Although there are a few examples of synthetic counterparts of the FeMoco, metal-sulfur cluster, which have shown binding of N2 (refs. 7-9), the reduction of N2 by any synthetic metal-sulfur cluster or by the extracted form of FeMoco10 has remained elusive, despite nearly 50 years of research. Here we show that the Fe atoms in our synthetic [Mo3S4Fe] cubes11,12 can capture a N2 molecule and catalyse N2 silylation to form N(SiMe3)3 under treatment with excess sodium and trimethylsilyl chloride. These results exemplify the catalytic silylation of N2 by a synthetic metal-sulfur cluster and demonstrate the N2-reduction capability of Fe atoms in a sulfur-rich environment, which is reminiscent of the ability of FeMoco to bind and activate N2.
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3
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Tanifuji K, Ohki Y. Metal–Sulfur Compounds in N2 Reduction and Nitrogenase-Related Chemistry. Chem Rev 2020; 120:5194-5251. [DOI: 10.1021/acs.chemrev.9b00544] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Kazuki Tanifuji
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, California 92697-3900, United States
| | - Yasuhiro Ohki
- Department of Chemsitry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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4
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Tsukada S, Abe T, Abe N, Nakashima S, Yamamoto K, Gunji T. Benzenedithiolate-bridged MoFe complexes: structures, oxidation states, and reactivities. Dalton Trans 2020; 49:9048-9056. [DOI: 10.1039/d0dt01428a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The benzenedithiolate-bridged MoFe complexes were synthesized and the oxidation states of the metal centers elucidated.
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Affiliation(s)
- Satoru Tsukada
- Graduate School of Engineering
- Chiba University
- Chiba 263-8522
- Japan
| | - Takayuki Abe
- Department of Pure and Applied Chemistry
- Faculty of Science and Technology
- Tokyo University of Science
- Chiba 278-8510
- Japan
| | - Naoya Abe
- Department of Pure and Applied Chemistry
- Faculty of Science and Technology
- Tokyo University of Science
- Chiba 278-8510
- Japan
| | - Satoru Nakashima
- Graduate School of Science
- Hiroshima University
- Higashi-Hiroshima
- Japan
- Natural Science Centre for Basic Research and Development
| | - Kazuki Yamamoto
- Department of Pure and Applied Chemistry
- Faculty of Science and Technology
- Tokyo University of Science
- Chiba 278-8510
- Japan
| | - Takahiro Gunji
- Department of Pure and Applied Chemistry
- Faculty of Science and Technology
- Tokyo University of Science
- Chiba 278-8510
- Japan
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5
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Zanello P. Structure and electrochemistry of proteins harboring iron-sulfur clusters of different nuclearities. Part V. Nitrogenases. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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6
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Bouchard S, Bruschi M, De Gioia L, Le Roy C, Pétillon FY, Schollhammer P, Talarmin J. FeMo Heterobimetallic Dithiolate Complexes: Investigation of Their Electron Transfer Chemistry and Reactivity toward Acids, a Density Functional Theory Rationalization. Inorg Chem 2019; 58:679-694. [PMID: 30561200 DOI: 10.1021/acs.inorgchem.8b02861] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The electrochemical behavior of complexes [FeMo(CO)5(κ2-dppe)(μ-pdt)] (1) and [FeMo(CO)4(MeCN)(κ2-dppe)(μ-pdt)] (2), in the absence and in the presence of acid, has been investigated. The reduction of 1 follows at slow scan rates, in CH2Cl2-[NBu4][PF6] and acid-free media, an ECrevE mechanism that is supported by cyclic voltammetry (CV) experiments and digital CV simulations. In MeCN-[NBu4][PF6], the electrochemical reduction of 1 is the same as in dichloromethane and follows an ECE mechanism at slow scan rates, but with a positive shift of the redox potentials. In contrast, the oxidation of 1 is strongly solvent-dependent. In dichloromethane, the oxidation of 1 is reversible and involves a single electron, while in acetonitrile, it is irreversible at moderate and slow scan rates ( v ≤ ca. 1 V s-1), and some chemical reversibility is apparent at higher scan rates ( v = 10 V s-1). Density functional theory calculations revealed that the chemical step in the ECrevE mechanism corresponds to the dissociation of one PPh2 end of the diphosphine ligand and the transfer of the semibridging CO to the Fe atom, similarly to the mechanism observed in the FeFe analogue complex. However, in the case of 1, the subsequent coordination of the phosphine ligand to the other metal is an unfavorable process.
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Affiliation(s)
- Solène Bouchard
- UMR CNRS 6521 "Chimie, Electrochimie Moléculaires et Chimie Analytique", Université de Bretagne Occidentale, UFR Sciences et Techniques , CS 93837, 29238 Brest-Cedex 3 , France
| | - Maurizio Bruschi
- Department of Earth and Environmental Sciences , University of Milano-Bicocca , Piazza della Scienza 1 , 20126 Milan , Italy
| | - Luca De Gioia
- Department of Biotechnology and Bioscience , University of Milano-Bicocca , Piazza della Scienza 2 , 20126 Milan , Italy
| | - Christine Le Roy
- UMR CNRS 6521 "Chimie, Electrochimie Moléculaires et Chimie Analytique", Université de Bretagne Occidentale, UFR Sciences et Techniques , CS 93837, 29238 Brest-Cedex 3 , France
| | - François Y Pétillon
- UMR CNRS 6521 "Chimie, Electrochimie Moléculaires et Chimie Analytique", Université de Bretagne Occidentale, UFR Sciences et Techniques , CS 93837, 29238 Brest-Cedex 3 , France
| | - Philippe Schollhammer
- UMR CNRS 6521 "Chimie, Electrochimie Moléculaires et Chimie Analytique", Université de Bretagne Occidentale, UFR Sciences et Techniques , CS 93837, 29238 Brest-Cedex 3 , France
| | - Jean Talarmin
- UMR CNRS 6521 "Chimie, Electrochimie Moléculaires et Chimie Analytique", Université de Bretagne Occidentale, UFR Sciences et Techniques , CS 93837, 29238 Brest-Cedex 3 , France
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7
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Abstract
The FeMo-cofactor of nitrogenase, a metal–sulfur cluster that contains eight transition metals, promotes the conversion of dinitrogen into ammonia when stored in the protein. Although various metal–sulfur clusters have been synthesized over the past decades, their use in the activation of N2 has remained challenging, and even the FeMo-cofactor extracted from nitrogenase is not able to reduce N2. Herein, we report the activation of N2 by a metal–sulfur cluster that contains molybdenum and titanium. An N2 moiety bridging two [Mo3S4Ti] cubes is converted into NH3 and N2H4 upon treatment with Brønsted acids in the presence of a reducing agent. Nitrogenase—whose cofactor consists of a metal–sulfur cluster—catalyzes the production of NH3 from N2, but designing metal–sulfur complexes capable of promoting this conversion remains challenging. Here, the authors report on the activation of N2 by a metal–sulfur cluster containing [Mo3S4Ti] cubes, demonstrating NH3 and N2H4 production.
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8
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Morrison CN, Spatzal T, Rees DC. Reversible Protonated Resting State of the Nitrogenase Active Site. J Am Chem Soc 2017; 139:10856-10862. [PMID: 28692802 PMCID: PMC5553094 DOI: 10.1021/jacs.7b05695] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Protonated states of the nitrogenase
active site are mechanistically
significant since substrate reduction is invariably accompanied by
proton uptake. We report the low pH characterization by X-ray crystallography
and EPR spectroscopy of the nitrogenase molybdenum iron (MoFe) proteins
from two phylogenetically distinct nitrogenases (Azotobacter
vinelandii, Av, and Clostridium pasteurianum, Cp) at pHs between 4.5 and 8. X-ray data at pHs of 4.5–6
reveal the repositioning of side chains along one side of the FeMo-cofactor,
and the corresponding EPR data shows a new S = 3/2
spin system with spectral features similar to a state previously observed
during catalytic turnover. The structural changes suggest that FeMo-cofactor
belt sulfurs S3A or S5A are potential protonation sites. Notably,
the observed structural and electronic low pH changes are correlated
and reversible. The detailed structural rearrangements differ between
the two MoFe proteins, which may reflect differences in potential
protonation sites at the active site among nitrogenase species. These
observations emphasize the benefits of investigating multiple nitrogenase
species. Our experimental data suggest that reversible protonation
of the resting state is likely occurring, and we term this state “E0H+”, following the Lowe–Thorneley
naming scheme.
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Affiliation(s)
- Christine N Morrison
- Division of Chemistry and Chemical Engineering and ‡Howard Hughes Medical Institute, California Institute of Technology , Pasadena, California 91125, United States
| | - Thomas Spatzal
- Division of Chemistry and Chemical Engineering and ‡Howard Hughes Medical Institute, California Institute of Technology , Pasadena, California 91125, United States
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering and ‡Howard Hughes Medical Institute, California Institute of Technology , Pasadena, California 91125, United States
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9
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Rao L, Xu X, Adamo C. Theoretical Investigation on the Role of the Central Carbon Atom and Close Protein Environment on the Nitrogen Reduction in Mo Nitrogenase. ACS Catal 2016. [DOI: 10.1021/acscatal.5b02577] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Li Rao
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, Department of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Xin Xu
- Shanghai
Key Laboratory of Molecular Catalysis and Innovative Materials, MOE
Laboratory for Computational Physical Science, Department of Chemistry, Fudan University, Shanghai 200433, China
| | - Carlo Adamo
- Chimie ParisTech,
PSL Research University, CNRS, Institut de Recherche de Chimie Paris
(IRCP), F-75005 Paris, France
- Institut Universitaire de France, 103 Boulevard Saint Michel, F-75005 Paris, France
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10
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11
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Bjornsson R, Neese F, Schrock RR, Einsle O, DeBeer S. The discovery of Mo(III) in FeMoco: reuniting enzyme and model chemistry. J Biol Inorg Chem 2014; 20:447-60. [PMID: 25549604 PMCID: PMC4334110 DOI: 10.1007/s00775-014-1230-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 12/11/2014] [Indexed: 12/02/2022]
Abstract
Biological nitrogen fixation is enabled by molybdenum-dependent nitrogenase enzymes, which effect the reduction of dinitrogen to ammonia using an Fe7MoS9C active site, referred to as the iron molybdenum cofactor or FeMoco. In this mini-review, we summarize the current understanding of the molecular and electronic structure of FeMoco. The advances in our understanding of the active site structure are placed in context with the parallel evolution of synthetic model studies. The recent discovery of Mo(III) in the FeMoco active site is highlighted with an emphasis placed on the important role that model studies have played in this finding. In addition, the reactivities of synthetic models are discussed in terms of their relevance to the enzymatic system.
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Affiliation(s)
- Ragnar Bjornsson
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, 45470, Mülheim and Der Ruhr, Germany,
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12
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Gogoi U, Guha AK, Phukan AK. Tracing the route to ammonia: a theoretical study on the possible pathways for dinitrogen reduction with tripodal iron complexes. Chemistry 2013; 19:11077-89. [PMID: 23821310 DOI: 10.1002/chem.201300991] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/14/2013] [Indexed: 11/08/2022]
Abstract
The chemistry of nitrogen fixation has been the subject of considerable research with a view to gaining a proper understanding of the mechanistic details. In this article, density functional calculations are performed on all the mechanistic possibilities for dinitrogen reduction mediated by the tripodal iron complexes [(SiP(Me)3)Fe(I)] ([Fe(Si)]) and [(BP(Me)3)Fe(0)] ([Fe(B)]). Dinitrogen addition to the neutral bare complex is found to be thermodynamically more favorable than that to the anionic one. Both symmetric and asymmetric pathways, along with the possible intermediates and transition states, are considered in this study. For both systems, the symmetric path is found to be more likely, although the prospect of the asymmetric path cannot be ignored. Moreover, interconversions between these two pathways are found to be less likely. This study corroborates most experimental observations and provides theoretical insight into the possible existence of some hitherto unknown intermediates such as multiple-bonded Fe-N species in a trigonal bipyramidal geometry. Furthermore, in agreement with experimental observations, this study also highlights the possibility of hydrogen and hydrazine evolution during the complete reduction of dinitrogen.
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Affiliation(s)
- Ujjal Gogoi
- Department of Chemical Sciences, Tezpur University, Napaam-784028, Assam, India
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13
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14
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Ogawa T, Kajita Y, Wasada-Tsutsui Y, Wasada H, Masuda H. Preparation, Characterization, and Reactivity of Dinitrogen Molybdenum Complexes with Bis(diphenylphosphino)amine Derivative Ligands that Form a Unique 4-Membered P–N–P Chelate Ring. Inorg Chem 2012; 52:182-95. [DOI: 10.1021/ic301577a] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Takahiko Ogawa
- Department of Frontier Materials,
Graduate School of Engineering, Nagoya Institute of Technology Gokiso, Showa, Nagoya 466-8555, Japan
| | - Yuji Kajita
- Department of Frontier Materials,
Graduate School of Engineering, Nagoya Institute of Technology Gokiso, Showa, Nagoya 466-8555, Japan
| | - Yuko Wasada-Tsutsui
- Department of Frontier Materials,
Graduate School of Engineering, Nagoya Institute of Technology Gokiso, Showa, Nagoya 466-8555, Japan
| | - Hiroaki Wasada
- Faculty of Regional Studies, Gifu University, Gifu 501-1193, Japan
| | - Hideki Masuda
- Department of Frontier Materials,
Graduate School of Engineering, Nagoya Institute of Technology Gokiso, Showa, Nagoya 466-8555, Japan
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15
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Kaliva M, Gabriel C, Raptopoulou CP, Terzis A, Voyiatzis G, Zervou M, Mateescu C, Salifoglou A. A Unique Dinuclear Mixed V(V) Oxo-peroxo Complex in the Structural Speciation of the Ternary V(V)-Peroxo-citrate System. Potential Mechanistic and Structural Insight into the Aqueous Synthetic Chemistry of Dinuclear V(V)-Citrate Species with H2O2. Inorg Chem 2011; 50:11423-36. [DOI: 10.1021/ic201204s] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. Kaliva
- Department of Chemistry, University of Crete, Heraklion 71409, Greece
| | - C. Gabriel
- Laboratory of Inorganic Chemistry, Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - C. P. Raptopoulou
- Institute of Materials Science, NCSR “Demokritos”, Aghia Paraskevi 15310, Attiki, Greece
| | - A. Terzis
- Institute of Materials Science, NCSR “Demokritos”, Aghia Paraskevi 15310, Attiki, Greece
| | - G. Voyiatzis
- Foundation for Research and Technology Hellas (FORTH), Institute of Chemical Engineering and High Temperature Chemical Processes (ICE/HT), Patras 26500, Greece
| | - M. Zervou
- Laboratory of Molecular Analysis, Institute of Organic and Pharmaceutical Chemistry, National Hellenic Research Foundation, Athens 11635, Greece
| | - C. Mateescu
- Banat University of Agricultural Sciences and Veterinary Medicine, Timisoara 1900, Romania
| | - A. Salifoglou
- Laboratory of Inorganic Chemistry, Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
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16
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Harris TV, Szilagyi RK. Nitrogenase structure and function relationships by density functional theory. Methods Mol Biol 2011; 766:267-291. [PMID: 21833874 DOI: 10.1007/978-1-61779-194-9_18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Modern density functional theory has tremendous potential with matching popularity in metalloenzymology to reveal the unseen atomic and molecular details of structural data, spectroscopic measurements, and biochemical experiments by providing insights into unobservable structures and states, while also offering theoretical justifications for observed trends and differences. An often untapped potential of this theoretical approach is to bring together diverse experimental structural and reactivity information and allow for these to be critically evaluated at the same level. This is particularly applicable for the tantalizingly complex problem of the structure and molecular mechanism of biological nitrogen fixation. In this chapter we provide a review with extensive practical details of the compilation and evaluation of experimental data for an unbiased and systematic density functional theory analysis that can lead to remarkable new insights about the structure-function relationships of the iron-sulfur clusters of nitrogenase.
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Affiliation(s)
- Travis V Harris
- Department of Chemistry and Biochemistry, Astrobiology Biogeochemistry Research Center, Montana State University, Bozeman, MT 59717, USA.
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17
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Abstract
Nitrogenase is the enzyme responsible for biological reduction of dinitrogen (N(2)) to ammonia, a form usable for life. Playing a central role in the global biogeochemical nitrogen cycle, this enzyme has been the focus of intensive research for over 60 years. This chapter provides an overview of the features of nitrogenase as a background to the subsequent chapters of this volume that detail the many methods that have been applied in an attempt to gain a deeper understanding of this complex enzyme.
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Affiliation(s)
- Zhi-Yong Yang
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA.
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18
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19
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Abstract
Nitrogen-fixing bacteria catalyze the reduction of dinitrogen (N(2)) to two ammonia molecules (NH(3)), the major contribution of fixed nitrogen to the biogeochemical nitrogen cycle. The most widely studied nitrogenase is the molybdenum (Mo)-dependent enzyme. The reduction of N(2) by this enzyme involves the transient interaction of two component proteins, designated the iron (Fe) protein and the MoFe protein, and minimally requires 16 magnesium ATP (MgATP), eight protons, and eight electrons. The current state of knowledge on how these proteins and small molecules together effect the reduction of N(2) to ammonia is reviewed. Included is a summary of the roles of the Fe protein and MgATP hydrolysis, information on the roles of the two metal clusters contained in the MoFe protein in catalysis, insights gained from recent success in trapping substrates and inhibitors at the active-site metal cluster FeMo cofactor, and finally, considerations of the mechanism of N(2) reduction catalyzed by nitrogenase.
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Affiliation(s)
- Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA.
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20
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Cui LF, Li DM, Wu JF, Cui XB, Wang TG, Xu JQ. Synthesis, structural determination and photochromism characterization of two complexes with [MO2(O2CCOPh2)2]2− cores [M=Mo or W]. J Mol Struct 2006. [DOI: 10.1016/j.molstruc.2006.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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21
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22
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Le Goff A, Le Roy C, Pétillon FY, Schollhammer P, Talarmin J. Oxidatively-induced μ-η1→ μ-η1:η1rearrangement of {NN} ligands at a {Mo2(μ-SMe)3} site and protonation of the oxidized diazenido complex. NEW J CHEM 2006. [DOI: 10.1039/b601377e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Kästner J, Blöchl PE. Model for Acetylene Reduction by Nitrogenase Derived from Density Functional Theory. Inorg Chem 2005; 44:4568-75. [PMID: 15962963 DOI: 10.1021/ic0500311] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The catalytic cycle of acetylene reduction at the FeMo cofactor of nitrogenase has been investigated on the basis of density functional theory. C2H2 binds to the same site as N2, but it binds to a less reduced state of the cofactor. In a manner similar to that of N2 binding, one of the sulfur bridges opens during acetylene binding. The model explains the strong noncompetitive inhibition of N2 reduction by C2H2 and the weak competitive inhibition of C2H2 reduction by N2. Our proposed mechanism is consistent with experimentally observed stereoselectivity and the ability of C2H2 to suppress H2 production by nitrogenase.
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Affiliation(s)
- Johannes Kästner
- Institute for Theoretical Physics, Clausthal University of Technology, D-38678 Clausthal-Zellerfeld, Germany
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24
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Henderson RA. Mechanistic Studies on Synthetic Fe−S-Based Clusters and Their Relevance to the Action of Nitrogenases. Chem Rev 2005; 105:2365-437. [PMID: 15941217 DOI: 10.1021/cr030706m] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Kaliva M, Raptopoulou CP, Terzis A, Salifoglou A. Systematic studies on pH-dependent transformations of dinuclear vanadium(V)-citrate complexes in aqueous solutions. A perspective relevance to aqueous vanadium(V)-citrate speciation. J Inorg Biochem 2003; 93:161-73. [PMID: 12576278 DOI: 10.1016/s0162-0134(02)00563-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Vanadium(V) involvement in interactions with physiological ligands in biological media prompted us to delve into the systematic pH-dependent synthesis, spectroscopic characterization, and perusal of chemical properties of arising aqueous vanadium(V)-citrate species in the requisite system. To this end, facile reactions led to dinuclear complexes (NH(4))(4)[V(2)O(4)(C(6)H(5)O(7))(2)].4H(2)O (1) and (NH(4))(6)[V(2)O(4)(C(6)H(4)O(7))(2)].6H(2)O (2). Complex 1 and 2 were characterized by elemental analysis, FT-IR and X-ray crystallography. Complex 1 crystallizes in the monoclinic space group C2/c with a=16.998(5) A, b=16.768(5) A, c=9.546(3) A, beta=105.22(1) degrees, V=2625(1) A(3), and Z=4. Complex 2 crystallizes in the triclinic space group P1;, with a=9.795(4) A, b=9.942(4) A, c=9.126(3) A, alpha=90.32(1) degrees, beta=111.69(1) degrees, gamma=108.67(1) degrees, V=774.5(5) A(3), and Z=1. The structures of 1 and 2 were consistent with the presence of a V(V)(2)O(2) core, to which citrate ligands of differing protonation state were bound in a coordination mode consistent with past observations. Ultimately, the aqueous pH dependent transformations of a series of three dinuclear complexes, 1, 2 and (NH(4))(2)[V(2)O(4)(C(6)H(6)O(7))(2)].2H(2)O (3), all isolated at pH values from 3 to 7.5, were explored and revealed an important interconnection among all species. Collectively, pH emerged as a determining factor of structural attributes in all three complexes, with the adjoining acid-base chemistry unfolding around the stable V(V)(2)O(2) core. The results point to the participation of all three species in aqueous vanadium(V)-citrate speciation, and may relate the site-specific protonations-deprotonations on the dinuclear complexes to potential biological processes involving vanadium(V) and physiological ligand targets.
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Affiliation(s)
- M Kaliva
- Department of Chemistry, University of Crete, 71409 Heraklion, Greece
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McLean PA, True A, Nelson MJ, Lee HI, Hoffman BM, Orme-Johnson WH. Effects of substrates (methyl isocyanide, C2H2) and inhibitor (CO) on resting-state wild-type and NifV(-)Klebsiella pneumoniae MoFe proteins. J Inorg Biochem 2003; 93:18-32. [PMID: 12538049 DOI: 10.1016/s0162-0134(02)00580-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We report the use of electron nuclear double resonance (ENDOR) spectroscopy to examine how the metal sites in the FeMo-cofactor cluster of the resting nitrogenase MoFe protein respond to addition of the substrates acetylene and methyl isocyanide and the inhibitor carbon monoxide. 1H, 57Fe and 95Mo ENDOR measurements were performed on the wild-type and the NifV(-)proteins from Klebsiella pneumoniae. Among the molecules tested, only the addition of acetylene to either protein induced widespread changes in the 57Fe ENDOR spectra. Acetylene also induced increases in intensity from unresolved protons in the proton ENDOR spectra. Thus we conclude that acetylene may bind to the resting-state MoFe protein to perturb the FeMo-cofactor environment. On the other hand, the present results show that methyl isocyanide and carbon monoxide do not substantially alter the FeMo cofactor's geometric and electronic structures. We interpret this as lack of interaction between those two molecules and the FeMo cofactor in the resting state MoFe protein. Thus, although it is generally accepted that substrates or inhibitors bind to the FeMo-cofactor only under turnover condition, this work provides evidence that at least one substrate can perturb the active site of nitrogenase under non-catalytic conditions.
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Affiliation(s)
- Paul A McLean
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Miki Y, Takagi H, Ichimura A, Akashi H, Shibahara T. Redox Chemistry of Dinuclear Molybdenum Dithiolene Complexes. Interconversion of the Bridging Disulfide and Sulfides. CHEM LETT 2002. [DOI: 10.1246/cl.2002.482] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Coucouvanis D, Han J, Moon N. Synthesis and characterization of sulfur-voided cubanes. Structural analogues for the MoFe(3)S(3) subunit in the nitrogenase cofactor. J Am Chem Soc 2002; 124:216-24. [PMID: 11782173 DOI: 10.1021/ja0110832] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new class of Mo/Fe/S clusters with the MoFe(3)S(3) core has been synthesized in attempts to model the FeMo-cofactor in nitrogenase. These clusters are obtained in reactions of the (Cl(4)-cat)(2)Mo(2)Fe(6)S(8)(PR(3))(6) [R = Et (I), (n)Pr (II)] clusters with CO. The new clusters include those preliminarily reported: (Cl(4)-cat)MoFe(3)S(3)(PEt(3))(2)(CO)(6) (III), (Cl(4)-cat)(O)MoFe(3)S(3)(PEt(3))(3)(CO)(5) (IV), (Cl(4)-cat)(Pyr)MoFe(3)S(3)(PEt(3))(2)(CO)(6) (VI), and (Cl(4)-cat)(Pyr)MoFe(3)S(3)(P(n)Pr(3))(3)(CO)(4) (VIII). In addition the new (Cl(4)-cat)(O)MoFe(3)S(3)(P(n)Pr(3))(3)(CO)(5) cluster (IVa), the (Cl(4)-cat)(O)MoFe(3)S(3)(PEt(3))(2)(CO)(6)cluster (V), the (Cl(4)-cat)(O)MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (Va), the (Cl(4)-cat)(Pyr)MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (VIa), and the (Cl(4)-cat)(P(n)Pr(3))MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (VII) also are reported. Clusters III-VIII have been structurally and spectroscopically characterized. EPR, zero-field (57)Fe-Mössbauer spectroscopic characterizations, and magnetic susceptibility measurements have been used for a tentative assignment of the electronic and oxidation states of the MoFe(3)S(3) sulfur-voided cuboidal clusters. A structural comparison of the clusters with the MoFe(3)S(3) subunit of the FeMo-cofactor has led to the suggestion that the storage of reducing equivalents into M-M bonds, and their use in the reduction of substrates, may occur with the FeMo-cofactor, which also appears to have M-M bonding. On the basis of this argument, a possible N(2)-binding and reduction mechanism on the FeMoco-cofactor is proposed.
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Affiliation(s)
- Dimitri Coucouvanis
- Department of Chemistry and the Biophysics Research Division, The University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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Tsaramyrsi M, Kavousanaki D, Raptopoulou C, Terzis A, Salifoglou A. Systematic synthesis, structural characterization, and reactivity studies of vanadium(V)–citrate anions [VO2(C6H6O7)]22−, isolated from aqueous solutions in the presence of different cations. Inorganica Chim Acta 2001. [DOI: 10.1016/s0020-1693(01)00464-9] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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