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Kajita Y, Kubo M, Arii H, Ishikawa S, Saito Y, Wasada-Tsutsui Y, Funahashi Y, Ozawa T, Masuda H. Preparations of trans- and cis- μ-1,2-Peroxodiiron(III) Complexes. Molecules 2023; 29:205. [PMID: 38202788 PMCID: PMC10780643 DOI: 10.3390/molecules29010205] [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: 12/20/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
The iron(II) complex with cis,cis-1,3,5-tris(benzylamino)cyclohexane (Bn3CY) (1) has been synthesized and characterized, which reacted with dioxygen to form the peroxo complex 2 in acetone at -60 °C. On the basis of spectroscopic measurements for 2, it was confirmed that the peroxo complex 2 has a trans-μ-1,2 fashion. Additionally, the peroxo complex 2 was reacted with benzoate anion as a bridging agent to give a peroxo complex 3. The results of resonance Raman and 1H-NMR studies supported that the peroxo complex 3 is a cis-μ-1,2-peroxodiiron(III) complex. These spectral features were interpreted by using DFT calculations.
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Affiliation(s)
- Yuji Kajita
- Department of Applied Chemistry, Graduate School of Engineering, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan;
| | - Masaki Kubo
- Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan; (M.K.); (Y.W.-T.); (T.O.)
| | - Hidekazu Arii
- Department of Education, Graduate School of Education, University of Miyazaki, Gakuenkibanadai-Nishi, Miyazaki 889-2192, Japan;
| | - Shinya Ishikawa
- Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan; (M.K.); (Y.W.-T.); (T.O.)
| | - Yamato Saito
- Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan; (M.K.); (Y.W.-T.); (T.O.)
| | - Yuko Wasada-Tsutsui
- Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan; (M.K.); (Y.W.-T.); (T.O.)
| | - Yasuhiro Funahashi
- Department of Chemistry, Graduate School of Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-0043, Japan;
| | - Tomohiro Ozawa
- Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan; (M.K.); (Y.W.-T.); (T.O.)
| | - Hideki Masuda
- Department of Applied Chemistry, Graduate School of Engineering, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan;
- Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan; (M.K.); (Y.W.-T.); (T.O.)
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2
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Stoichiometric Alkane and Aldehyde Hydroxylation Reactions Mediated by In Situ Generated Iron(III)-Iodosylbenzene Adduct. Molecules 2023; 28:molecules28041855. [PMID: 36838842 PMCID: PMC9958819 DOI: 10.3390/molecules28041855] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 02/06/2023] [Accepted: 02/14/2023] [Indexed: 02/18/2023] Open
Abstract
Previously synthesized and spectroscopically characterized mononuclear nonheme, low-spin iron(III)-iodosylbenzene complex bearing a bidentate pyridyl-benzimidazole ligands has been investigated in alkane and aldehyde oxidation reactions. The in situ generated Fe(III) iodosylbenzene intermediate is a reactive oxidant capable of activating the benzylic C-H bond of alkane. Its electrophilic character was confirmed by using substituted benzaldehydes and a modified ligand framework containing electron-donating (Me) substituents. Furthermore, the results of kinetic isotope experiments (KIE) using deuterated substrate indicate that the C-H activation can be interpreted through a tunneling-like HAT mechanism. Based on the results of the kinetic measurements and the relatively high KIE values, we can conclude that the activation of the C-H bond mediated by iron(III)-iodosylbenzene adducts is the rate-determining step.
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Walleck S, Zimmermann TP, Hachmeister H, Pilger C, Huser T, Katz S, Hildebrandt P, Stammler A, Bögge H, Bill E, Glaser T. Generation of a μ-1,2-hydroperoxo Fe IIIFe III and a μ-1,2-peroxo Fe IVFe III Complex. Nat Commun 2022; 13:1376. [PMID: 35296656 PMCID: PMC8927127 DOI: 10.1038/s41467-022-28894-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 02/17/2022] [Indexed: 12/05/2022] Open
Abstract
μ-1,2-Peroxo-diferric intermediates (P) of non-heme diiron enzymes are proposed to convert upon protonation either to high-valent active species or to activated P′ intermediates via hydroperoxo-diferric intermediates. Protonation of synthetic μ-1,2-peroxo model complexes occurred at the μ-oxo and not at the μ-1,2-peroxo bridge. Here we report a stable μ-1,2-peroxo complex {FeIII(μ-O)(μ-1,2-O2)FeIII} using a dinucleating ligand and study its reactivity. The reversible oxidation and protonation of the μ-1,2-peroxo-diferric complex provide μ-1,2-peroxo FeIVFeIII and μ-1,2-hydroperoxo-diferric species, respectively. Neither the oxidation nor the protonation induces a strong electrophilic reactivity. Hence, the observed intramolecular C-H hydroxylation of preorganized methyl groups of the parent μ-1,2-peroxo-diferric complex should occur via conversion to a more electrophilic high-valent species. The thorough characterization of these species provides structure-spectroscopy correlations allowing insights into the formation and reactivities of hydroperoxo intermediates in diiron enzymes and their conversion to activated P′ or high-valent intermediates. Iron coordination complexes can be used to gain insight on biologically relevant iron-oxygen compounds generated in iron metalloenzymes. Here, the authors characterise a μ-1,2-hydroperoxo FeIIIFeIII and a μ-1,2-peroxo FeIVFeIII, and study their reactivity in C-H activation.
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Affiliation(s)
- Stephan Walleck
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Thomas Philipp Zimmermann
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Henning Hachmeister
- Biomolekulare Photonik, Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Christian Pilger
- Biomolekulare Photonik, Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Thomas Huser
- Biomolekulare Photonik, Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Sagie Katz
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, D-10623, Berlin, Germany
| | - Peter Hildebrandt
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, D-10623, Berlin, Germany
| | - Anja Stammler
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Hartmut Bögge
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, D-45470, Mülheim an der Ruhr, Germany
| | - Thorsten Glaser
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
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4
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Rohde GT, Xue G, Que L. Explorations of the nonheme high-valent iron-oxo landscape: crystal structure of a synthetic complex with an [FeIV2(μ-O) 2] diamond core relevant to the chemistry of sMMOH. Faraday Discuss 2022; 234:109-128. [PMID: 35171169 DOI: 10.1039/d1fd00066g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Methanotrophic bacteria utilize methane monooxygenase (MMO) to carry out the first step in metabolizing methane. The soluble enzymes employ a hydroxylase component (sMMOH) with a nonheme diiron active site that activates O2 and generates a powerful oxidant capable of converting methane to methanol. It is proposed that the diiron(II) center in the reduced enzyme reacts with O2 to generate a diferric-peroxo intermediate called P that then undergoes O-O cleavage to convert into a diiron(IV) derivative called Q, which carries out methane hydroxylation. Most (but not all) of the spectroscopic data of Q accumulated by various groups to date favor the presence of an FeIV2(μ-O)2 unit with a diamond core. The Que lab has had a long-term interest in making synthetic analogs of iron enzyme intermediates. To this end, the first crystal structure of a complex with a FeIIIFeIV(μ-O)2 diamond core was reported in 1999, which exhibited an Fe⋯Fe distance of 2.683(1) Å. Now more than 20 years later, a complex with an FeIV2(μ-O)2 diamond core has been synthesized in sufficient purity to allow diffraction-quality crystals to be grown. Its crystal structure has been solved, revealing an Fe⋯Fe distance of 2.711(4) Å for comparison with structural data for related complexes with lower iron oxidation states.
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Affiliation(s)
- Gregory T Rohde
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | - Genqiang Xue
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | - Lawrence Que
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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5
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Gordon JB, Albert T, Dey A, Sabuncu S, Siegler MA, Bill E, Moënne-Loccoz P, Goldberg DP. A Reactive, Photogenerated High-Spin ( S = 2) Fe IV(O) Complex via O 2 Activation. J Am Chem Soc 2021; 143:21637-21647. [PMID: 34913683 PMCID: PMC9109941 DOI: 10.1021/jacs.1c10051] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Addition of dioxygen at low temperature to the non-heme ferrous complex FeII(Me3TACN)((OSiPh2)2O) (1) in 2-MeTHF produces a peroxo-bridged diferric complex Fe2III(μ-O2)(Me3TACN)2((OSiPh2)2O)2 (2), which was characterized by UV-vis, resonance Raman, and variable field Mössbauer spectroscopies. Illumination of a frozen solution of 2 in THF with white light leads to homolytic O-O bond cleavage and generation of a FeIV(O) complex 4 (ν(Fe=O) = 818 cm-1; δ = 0.22 mm s-1, ΔEQ = 0.23 mm s-1). Variable field Mössbauer spectroscopy measurements show that 4 is a rare example of a high-spin S = 2 FeIV(O) complex and the first synthetic example to be generated directly from O2. Complex 4 is highly reactive, as expected for a high-spin ferryl, and decays rapidly in fluid solution at cryogenic temperatures. This decay process in 2-MeTHF involves C-H cleavage of the solvent. However, the controlled photolysis of 2 in situ with visible light and excess phenol substrate leads to competitive phenol oxidation, via the proposed transient generation of 4 as the active oxidant.
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Affiliation(s)
- Jesse B. Gordon
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Therese Albert
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Aniruddha Dey
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Sinan Sabuncu
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Maxime A. Siegler
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Eckhard Bill
- Department of Inorganic Spectroscopy / Joint Workspace, Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34−36, 45470 Mülheim-an-der-Ruhr, Germany,Corresponding Author: , ,
| | - Pierre Moënne-Loccoz
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, USA,Corresponding Author: , ,
| | - David P. Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA,Corresponding Author: , ,
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6
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Manley OM, Tang H, Xue S, Guo Y, Chang WC, Makris TM. BesC Initiates C-C Cleavage through a Substrate-Triggered and Reactive Diferric-Peroxo Intermediate. J Am Chem Soc 2021; 143:21416-21424. [PMID: 34898198 PMCID: PMC8876372 DOI: 10.1021/jacs.1c11109] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BesC catalyzes the iron- and O2-dependent cleavage of 4-chloro-l-lysine to form 4-chloro-l-allylglycine, formaldehyde, and ammonia. This process is a critical step for a biosynthetic pathway that generates a terminal alkyne amino acid which can be leveraged as a useful bio-orthogonal handle for protein labeling. As a member of an emerging family of diiron enzymes that are typified by their heme oxygenase-like fold and a very similar set of coordinating ligands, recently termed HDOs, BesC performs an unusual type of carbon-carbon cleavage reaction that is a significant departure from reactions catalyzed by canonical dinuclear-iron enzymes. Here, we show that BesC activates O2 in a substrate-gated manner to generate a diferric-peroxo intermediate. Examination of the reactivity of the peroxo intermediate with a series of lysine derivatives demonstrates that BesC initiates this unique reaction trajectory via cleavage of the C4-H bond; this process represents the rate-limiting step in a single turnover reaction. The observed reactivity of BesC represents the first example of a dinuclear-iron enzyme that utilizes a diferric-peroxo intermediate to capably cleave a C-H bond as part of its native function, thus circumventing the formation of a high-valent intermediate more commonly associated with substrate monooxygenations.
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Affiliation(s)
- Olivia M. Manley
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Haoyu Tang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Shan Xue
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Wei-chen Chang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Thomas M. Makris
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, United States,Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
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7
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Brewer SM, Schwartz TM, Mekhail MA, Turan LS, Prior TJ, Hubin TJ, Janesko BG, Green KN. Mechanistic Insights into Iron-Catalyzed C–H Bond Activation and C–C Coupling. Organometallics 2021; 40:2467-2477. [DOI: 10.1021/acs.organomet.1c00211] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Samantha M. Brewer
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Timothy M. Schwartz
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Magy A. Mekhail
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Lara S. Turan
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Timothy J. Prior
- Department of Chemistry and Biochemistry, University of Hull, Hull HU6 7RX, U.K
| | - Timothy J. Hubin
- Department of Chemistry and Physics, Southwestern Oklahoma State University, 100 Campus Drive, Weatherford, Oklahoma 73096, United States
| | - Benjamin G. Janesko
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, Texas 76129, United States
| | - Kayla N. Green
- Department of Chemistry and Biochemistry, Texas Christian University, 2950 S. Bowie, Fort Worth, Texas 76129, United States
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8
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Yadav O, Ansari M, Ansari A. Electronic structures, bonding and energetics of non-heme mono and dinuclear iron-TPA complexes: a computational exploration. Struct Chem 2021. [DOI: 10.1007/s11224-021-01775-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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9
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Pullin J, Wilson MT, Clémancey M, Blondin G, Bradley JM, Moore GR, Le Brun NE, Lučić M, Worrall JAR, Svistunenko DA. Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H 2O 2 but Slowly with O 2. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 133:8442-8450. [PMID: 38529354 PMCID: PMC10962548 DOI: 10.1002/ange.202015964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/05/2021] [Indexed: 11/09/2022]
Abstract
Both O2 and H2O2 can oxidize iron at the ferroxidase center (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV/Vis, EPR, and Mössbauer spectroscopies have been used to follow the reactions when apo-EcBfr, pre-loaded anaerobically with Fe2+, was exposed to O2 or H2O2. We show that O2 binds di-Fe2+ FC reversibly, two Fe2+ ions are oxidized in concert and a H2O2 molecule is formed and released to the solution. This peroxide molecule further oxidizes another di-Fe2+ FC, at a rate circa 1000 faster than O2, ensuring an overall 1:4 stoichiometry of iron oxidation by O2. Initially formed Fe3+ can further react with H2O2 (producing protein bound radicals) but relaxes within seconds to an H2O2-unreactive di-Fe3+ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H2O2 rather than sequester iron.
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Affiliation(s)
- Jacob Pullin
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
| | - Michael T. Wilson
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
| | - Martin Clémancey
- Université Grenoble AlpesCNRS, CEA, IRIGLaboratoire de Chimie et Biologie des Métaux, UMR 524917 rue des Martyrs38000GrenobleFrance
| | - Geneviève Blondin
- Université Grenoble AlpesCNRS, CEA, IRIGLaboratoire de Chimie et Biologie des Métaux, UMR 524917 rue des Martyrs38000GrenobleFrance
| | - Justin M. Bradley
- School of ChemistryUniversity of East AngliaNorwich Research Park NorwichNorfolkNR4 7TJUK
| | - Geoffrey R. Moore
- School of ChemistryUniversity of East AngliaNorwich Research Park NorwichNorfolkNR4 7TJUK
| | - Nick E. Le Brun
- School of ChemistryUniversity of East AngliaNorwich Research Park NorwichNorfolkNR4 7TJUK
| | - Marina Lučić
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
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10
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Pullin J, Wilson MT, Clémancey M, Blondin G, Bradley JM, Moore GR, Le Brun NE, Lučić M, Worrall JAR, Svistunenko DA. Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H 2 O 2 but Slowly with O 2. Angew Chem Int Ed Engl 2021; 60:8361-8369. [PMID: 33482043 PMCID: PMC8049013 DOI: 10.1002/anie.202015964] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/05/2021] [Indexed: 01/08/2023]
Abstract
Both O2 and H2O2 can oxidize iron at the ferroxidase center (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV/Vis, EPR, and Mössbauer spectroscopies have been used to follow the reactions when apo‐EcBfr, pre‐loaded anaerobically with Fe2+, was exposed to O2 or H2O2. We show that O2 binds di‐Fe2+ FC reversibly, two Fe2+ ions are oxidized in concert and a H2O2 molecule is formed and released to the solution. This peroxide molecule further oxidizes another di‐Fe2+ FC, at a rate circa 1000 faster than O2, ensuring an overall 1:4 stoichiometry of iron oxidation by O2. Initially formed Fe3+ can further react with H2O2 (producing protein bound radicals) but relaxes within seconds to an H2O2‐unreactive di‐Fe3+ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H2O2 rather than sequester iron.
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Affiliation(s)
- Jacob Pullin
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Michael T Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Martin Clémancey
- Université Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, UMR 5249, 17 rue des Martyrs, 38000, Grenoble, France
| | - Geneviève Blondin
- Université Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, UMR 5249, 17 rue des Martyrs, 38000, Grenoble, France
| | - Justin M Bradley
- School of Chemistry, University of East Anglia, Norwich Research Park Norwich, Norfolk, NR4 7TJ, UK
| | - Geoffrey R Moore
- School of Chemistry, University of East Anglia, Norwich Research Park Norwich, Norfolk, NR4 7TJ, UK
| | - Nick E Le Brun
- School of Chemistry, University of East Anglia, Norwich Research Park Norwich, Norfolk, NR4 7TJ, UK
| | - Marina Lučić
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Jonathan A R Worrall
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Dimitri A Svistunenko
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
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11
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Török P, Unjaroen D, Viktória Csendes F, Giorgi M, Browne WR, Kaizer J. A nonheme peroxo-diiron(III) complex exhibiting both nucleophilic and electrophilic oxidation of organic substrates. Dalton Trans 2021; 50:7181-7185. [PMID: 34019062 PMCID: PMC8168641 DOI: 10.1039/d1dt01502h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The complex [FeIII2(μ-O2)(L3)4(S)2]4+ (L3 = 2-(4-thiazolyl)benzimidazole, S = solvent) forms upon reaction of [FeII(L3)2] with H2O2 and is a functional model of peroxo-diiron intermediates invoked during the catalytic cycle of oxidoreductases. The spectroscopic properties of the complex are in line with those of complexes formed with N-donor ligands. [FeIII2(μ-O2)(L3)4(S)2]4+ shows both nucleophilic (aldehydes) and electrophilic (phenol, N,N-dimethylanilines) oxidative reactivity and unusually also electron transfer oxidation. A bidentate ligand based iron complex shows nucleophillic and electrophillice reactivity in the oxidation of organic substrates.![]()
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Affiliation(s)
- Patrik Török
- Research Group of Bioorganic and Biocoordination Chemistry, University of Pannonia, H-8200 Veszprém, Hungary.
| | - Duenpen Unjaroen
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
| | - Flóra Viktória Csendes
- Research Group of Bioorganic and Biocoordination Chemistry, University of Pannonia, H-8200 Veszprém, Hungary.
| | - Michel Giorgi
- Aix-Marseille Université, FR1739, Spectropole, Campus St Jérome, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France
| | - Wesley R Browne
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
| | - József Kaizer
- Research Group of Bioorganic and Biocoordination Chemistry, University of Pannonia, H-8200 Veszprém, Hungary.
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12
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Kripli B, Szávuly M, Csendes FV, Kaizer J. Functional models of nonheme diiron enzymes: reactivity of the μ-oxo-μ-1,2-peroxo-diiron(iii) intermediate in electrophilic and nucleophilic reactions. Dalton Trans 2020; 49:1742-1746. [PMID: 31967142 DOI: 10.1039/c9dt04551a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The reactivity of the previously reported peroxo-adduct [FeIII2(μ-O)(μ-1,2-O2)(IndH)2(solv)2]2+ (1) (IndH = 1,3-bis(2-pyridyl-imino)isoindoline) has been investigated in nucleophilic (e.g., deformylation of alkyl and aryl alkyl aldehydes) and electrophilic (e.g. oxidation of phenols) stoichiometric reactions as biomimics of ribonucleotide reductase (RNR-R2) and aldehyde deformylating oxygenase (ADO) enzymes. Based on detailed kinetic and mechanistic studies, we have found further evidence for the ambiphilic behaviour of the peroxo intermediates proposed for diferric oxidoreductase enzymes.
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Affiliation(s)
- Balázs Kripli
- Department of Chemistry, University of Pannonia, H-8201 Veszprém, Hungary.
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14
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Kass D, Corona T, Warm K, Braun-Cula B, Kuhlmann U, Bill E, Mebs S, Swart M, Dau H, Haumann M, Hildebrandt P, Ray K. Stoichiometric Formation of an Oxoiron(IV) Complex by a Soluble Methane Monooxygenase Type Activation of O 2 at an Iron(II)-Cyclam Center. J Am Chem Soc 2020; 142:5924-5928. [PMID: 32168447 DOI: 10.1021/jacs.9b13756] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In soluble methane monooxygenase enzymes (sMMO), dioxygen (O2) is activated at a diiron(II) center to form an oxodiiron(IV) intermediate Q that performs the challenging oxidation of methane to methanol. An analogous mechanism of O2 activation at mono- or dinuclear iron centers is rare in the synthetic chemistry. Herein, we report a mononuclear non-heme iron(II)-cyclam complex, 1-trans, that activates O2 to form the corresponding iron(IV)-oxo complex, 2-trans, via a mechanism reminiscent of the O2 activation process in sMMO. The conversion of 1-trans to 2-trans proceeds via the intermediate formation of an iron(III)-superoxide species 3, which could be trapped and spectroscopically characterized at -50 °C. Surprisingly, 3 is a stronger oxygen atom transfer (OAT) agent than 2-trans; 3 performs OAT to 1-trans or PPh3 to yield 2-trans quantitatively. Furthermore, 2-trans oxidizes the aromatic C-H bonds of 2,6-di-tert-butylphenol, which, together with the strong OAT ability of 3, represents new domains of oxoiron(IV) and superoxoiron(III) reactivities.
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Affiliation(s)
- Dustin Kass
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Teresa Corona
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Katrin Warm
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Beatrice Braun-Cula
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Uwe Kuhlmann
- Department of Chemistry, Technische Universität Berlin, Straβe des 17. Juni 135, 10623 Berlin, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Stefan Mebs
- Department of Physics, Freie Universität Berlin, Arminallee 14, 14195 Berlin, Germany
| | - Marcel Swart
- ICREA, Lluis Companys 23, 08010 Barcelona, Spain.,IQCC, Universitat de Girona, Campus Montilivi, 17003 Girona, Spain
| | - Holger Dau
- Department of Physics, Freie Universität Berlin, Arminallee 14, 14195 Berlin, Germany
| | - Michael Haumann
- Department of Physics, Freie Universität Berlin, Arminallee 14, 14195 Berlin, Germany
| | - Peter Hildebrandt
- Department of Chemistry, Technische Universität Berlin, Straβe des 17. Juni 135, 10623 Berlin, Germany
| | - Kallol Ray
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
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15
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Banerjee S, Draksharapu A, Crossland PM, Fan R, Guo Y, Swart M, Que L. Sc 3+-Promoted O-O Bond Cleavage of a (μ-1,2-Peroxo)diiron(III) Species Formed from an Iron(II) Precursor and O 2 to Generate a Complex with an Fe IV2(μ-O) 2 Core. J Am Chem Soc 2020; 142:4285-4297. [PMID: 32017545 DOI: 10.1021/jacs.9b12081] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Soluble methane monooxygenase (sMMO) carries out methane oxidation at 4 °C and under ambient pressure in a catalytic cycle involving the formation of a peroxodiiron(III) intermediate (P) from the oxygenation of the diiron(II) enzyme and its subsequent conversion to Q, the diiron(IV) oxidant that hydroxylates methane. Synthetic diiron(IV) complexes that can serve as models for Q are rare and have not been generated by a reaction sequence analogous to that of sMMO. In this work, we show that [FeII(Me3NTB)(CH3CN)](CF3SO3)2 (Me3NTB = tris((1-methyl-1H-benzo[d]imidazol-2-yl)methyl)amine) (1) reacts with O2 in the presence of base, generating a (μ-1,2-peroxo)diiron(III) adduct with a low O-O stretching frequency of 825 cm-1 and a short Fe···Fe distance of 3.07 Å. Even more interesting is the observation that the peroxodiiron(III) complex undergoes O-O bond cleavage upon treatment with the Lewis acid Sc3+ and transforms into a bis(μ-oxo)diiron(IV) complex, thus providing a synthetic precedent for the analogous conversion of P to Q in the catalytic cycle of sMMO.
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Affiliation(s)
- Saikat Banerjee
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Patrick M Crossland
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Ruixi Fan
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Marcel Swart
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain.,IQCC and Department of Chemistry, University of Girona, 17003 Girona, Spain
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
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16
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Gordon JB, Vilbert AC, DiMucci IM, MacMillan SN, Lancaster KM, Moënne-Loccoz P, Goldberg DP. Activation of Dioxygen by a Mononuclear Nonheme Iron Complex: Sequential Peroxo, Oxo, and Hydroxo Intermediates. J Am Chem Soc 2019; 141:17533-17547. [PMID: 31647656 DOI: 10.1021/jacs.9b05274] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The activation of dioxygen by FeII(Me3TACN)(S2SiMe2) (1) is reported. Reaction of 1 with O2 at -135 °C in 2-MeTHF generates a thiolate-ligated (peroxo)diiron complex FeIII2(O2)(Me3TACN)2(S2SiMe2)2 (2) that was characterized by UV-vis (λmax = 300, 390, 530, 723 nm), Mössbauer (δ = 0.53, |ΔEQ| = 0.76 mm s-1), resonance Raman (RR) (ν(O-O) = 849 cm-1), and X-ray absorption (XAS) spectroscopies. Complex 2 is distinct from the outer-sphere oxidation product 1ox (UV-vis (λmax = 435, 520, 600 nm), Mössbauer (δ = 0.45, |ΔEQ| = 3.6 mm s-1), and EPR (S = 5/2, g = [6.38, 5.53, 1.99])), obtained by one-electron oxidation of 1. Cleavage of the peroxo O-O bond can be initiated either photochemically or thermally to produce a new species assigned as an FeIV(O) complex, FeIV(O)(Me3TACN)(S2SiMe2) (3), which was identified by UV-vis (λmax = 385, 460, 890 nm), Mössbauer (δ = 0.21, |ΔEQ| = 1.57 mm s-1), RR (ν(FeIV═O) = 735 cm-1), and X-ray absorption spectroscopies, as well as reactivity patterns. Reaction of 3 at low temperature with H atom donors gives a new species, FeIII(OH)(Me3TACN)(S2SiMe2) (4). Complex 4 was independently synthesized from 1 by the stoichiometric addition of a one-electron oxidant and a hydroxide source. This work provides a rare example of dioxygen activation at a mononuclear nonheme iron(II) complex that produces both FeIII-O-O-FeIII and FeIV(O) species in the same reaction with O2. It also demonstrates the feasibility of forming Fe/O2 intermediates with strongly donating sulfur ligands while avoiding immediate sulfur oxidation.
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Affiliation(s)
- Jesse B Gordon
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Avery C Vilbert
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Ida M DiMucci
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Pierre Moënne-Loccoz
- Department of Chemical Physiology and Biochemistry , Oregon Health & Science University , Portland , Oregon 97239 , United States
| | - David P Goldberg
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
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17
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Kripli B, Csendes FV, Török P, Speier G, Kaizer J. Stoichiometric Aldehyde Deformylation Mediated by Nucleophilic Peroxo-diiron(III) Complex as a Functional Model of Aldehyde Deformylating Oxygenase. Chemistry 2019; 25:14290-14294. [PMID: 31448834 DOI: 10.1002/chem.201903727] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Indexed: 11/11/2022]
Abstract
The reactivity of the previously reported peroxo adduct [FeIII 2 (μ-O2 )(MeBzim-Py)4 (CH3 CN)2 ]4+ (1) (MeBzim-Py=2-(2'-pyridyl)-N-methylbenzimidazole) towards aldehyde substrates including phenylacetaldehyde (PAA), hydrocinnamaldehyde (HCA), propionaldehyde (PA), 2-phenylpropionaldehyde (PPA), cyclohexanecarboxaldehyde (CCA), and para-substituted benzaldehydes (benzoyl chlorides) has been investigated. Complex 1 proved to be a nucleophilic oxidant in aldehyde deformylation reaction. These models, including detailed kinetic and mechanistic studies, may serve as the first biomimics of aldehyde deformylating oxygenase (ADO) enzymes.
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Affiliation(s)
- Balázs Kripli
- Department of Chemistry, University of Pannonia, 8201, Veszprém, Hungary
| | | | - Patrik Török
- Department of Chemistry, University of Pannonia, 8201, Veszprém, Hungary
| | - Gábor Speier
- Department of Chemistry, University of Pannonia, 8201, Veszprém, Hungary
| | - József Kaizer
- Department of Chemistry, University of Pannonia, 8201, Veszprém, Hungary
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18
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Lee CM, Sankaralingam M, Chuo CH, Tseng TH, Chen PPY, Chiang MH, Li XX, Lee YM, Nam W. A Mn(iv)-peroxo complex in the reactions with proton donors. Dalton Trans 2019; 48:5203-5213. [PMID: 30941378 DOI: 10.1039/c9dt00649d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Protons play an important role in promoting O-O or M-O bond cleavage of metal-peroxo complexes. Treatment of side-on O2-bound [PPN][MnIV(TMSPS3)(O2)] (1, PPN = bis(triphenylphosphine)iminium and TMSPS3H3 = 2,2',2''-trimercapto-3,3',3''-tris(trimethylsilyl)triphenylphosphine) with perchloric acid (HClO4) in the presence of PR3 (R = phenyl or p-tolyl) results in the formation of neutral five-coordinate MnIII(OPR3)(TMSPS3) complexes (R = phenyl, 2a; p-tolyl, 2b), which are confirmed by X-ray crystallography. Isotope labelling experiments demonstrate that the oxygen atom in the phosphine oxide product derives from the peroxo ligand of 1. Reactions of 1 with weak proton donors, such as phenylthiol, phenol, substituted phenol and methanol, are also investigated to explore the reactivity of the MnIV-peroxo complex, leading to the isolation of a series of five-coordinate [MnIII(L)(TMSPS3)]- complexes (L = phenylthiolate, phenolate or methoxide). Mechanistic aspects of the reactions of the MnIV-peroxo complex with proton donors are discussed as well.
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Affiliation(s)
- Chien-Ming Lee
- Department of Applied Science, National Taitung University, Jhihben Campus: 369, Sec. 2, University Rd., Taitung 950, Taiwan.
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19
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Komor AJ, Jasniewski AJ, Que L, Lipscomb JD. Diiron monooxygenases in natural product biosynthesis. Nat Prod Rep 2018; 35:646-659. [PMID: 29552683 PMCID: PMC6051903 DOI: 10.1039/c7np00061h] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covering: up to 2017 The participation of non-heme dinuclear iron cluster-containing monooxygenases in natural product biosynthetic pathways has been recognized only recently. At present, two families have been discovered. The archetypal member of the first family, CmlA, catalyzes β-hydroxylation of l-p-aminophenylalanine (l-PAPA) covalently linked to the nonribosomal peptide synthetase (NRPS) CmlP, thereby effecting the first step in the biosynthesis of chloramphenicol by Streptomyces venezuelae. CmlA houses the diiron cluster in a metallo-β-lactamase protein fold instead of the 4-helix bundle fold of nearly every other diiron monooxygenase. CmlA couples O2 activation and substrate hydroxylation via a structural change caused by formation of the l-PAPA-loaded CmlP:CmlA complex. The other new diiron family is typified by two enzymes, AurF and CmlI, which catalyze conversion of aryl-amine substrates to aryl-nitro products with incorporation of oxygen from O2. AurF from Streptomyces thioluteus catalyzes the formation of p-nitrobenzoate from p-aminobenzoate as a precursor to the biostatic compound aureothin, whereas CmlI from S. venezuelae catalyzes the ultimate aryl-amine to aryl-nitro step in chloramphenicol biosynthesis. Both enzymes stabilize a novel type of peroxo-intermediate as the reactive species. The rare 6-electron N-oxygenation reactions of CmlI and AurF involve two progressively oxidized pathway intermediates. The enzymes optimize efficiency by utilizing one of the reaction pathway intermediates as an in situ reductant for the diiron cluster, while simultaneously generating the next pathway intermediate. For CmlI, this reduction allows mid-pathway regeneration of the peroxo intermediate required to complete the biosynthesis. CmlI ensures specificity by carrying out the multistep aryl-amine oxygenation without dissociating intermediate products.
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Affiliation(s)
- Anna J Komor
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | - Andrew J Jasniewski
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | - Lawrence Que
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | - John D Lipscomb
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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20
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Jasniewski AJ, Que L. Dioxygen Activation by Nonheme Diiron Enzymes: Diverse Dioxygen Adducts, High-Valent Intermediates, and Related Model Complexes. Chem Rev 2018; 118:2554-2592. [PMID: 29400961 PMCID: PMC5920527 DOI: 10.1021/acs.chemrev.7b00457] [Citation(s) in RCA: 298] [Impact Index Per Article: 49.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A growing subset of metalloenzymes activates dioxygen with nonheme diiron active sites to effect substrate oxidations that range from the hydroxylation of methane and the desaturation of fatty acids to the deformylation of fatty aldehydes to produce alkanes and the six-electron oxidation of aminoarenes to nitroarenes in the biosynthesis of antibiotics. A common feature of their reaction mechanisms is the formation of O2 adducts that evolve into more reactive derivatives such as diiron(II,III)-superoxo, diiron(III)-peroxo, diiron(III,IV)-oxo, and diiron(IV)-oxo species, which carry out particular substrate oxidation tasks. In this review, we survey the various enzymes belonging to this unique subset and the mechanisms by which substrate oxidation is carried out. We examine the nature of the reactive intermediates, as revealed by X-ray crystallography and the application of various spectroscopic methods and their associated reactivity. We also discuss the structural and electronic properties of the model complexes that have been found to mimic salient aspects of these enzyme active sites. Much has been learned in the past 25 years, but key questions remain to be answered.
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Affiliation(s)
- Andrew J. Jasniewski
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
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21
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Sekino M, Furutachi H, Tojo R, Hishi A, Kajikawa H, Suzuki T, Suzuki K, Fujinami S, Akine S, Sakata Y, Ohta T, Hayami S, Suzuki M. New mechanistic insights into intramolecular aromatic ligand hydroxylation and benzyl alcohol oxidation initiated by the well-defined (μ-peroxo)diiron(iii) complex. Chem Commun (Camb) 2018; 53:8838-8841. [PMID: 28726874 DOI: 10.1039/c7cc04382a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A (μ-peroxo)diiron(iii) complex [Fe2(LPh4)(O2)(Ph3CCO2)]2+ (1-O2) with a dinucleating ligand (LPh4), generated from the reaction of a carboxylate bridged diiron(ii) complex [Fe2(LPh4)(Ph3CCO2)]2+ (1) with dioxygen in CH2Cl2, provides a diiron(iv)-oxo species as an active oxidant which is involved in either aromatic ligand hydroxylation or benzyl alcohol oxidation.
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Affiliation(s)
- Mio Sekino
- Department of Chemistry, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
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22
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Khenkin AM, Vedichi M, Shimon LJW, Cranswick MA, Klein JEMN, Que L, Neumann R. Hydrogen-Atom Transfer Oxidation with H 2O 2 Catalyzed by [FeII(1,2-bis(2,2'-bipyridyl-6-yl)ethane(H 2O) 2] 2+: Likely Involvement of a (μ-Hydroxo)(μ-1,2-peroxo)diiron(III) Intermediate. Isr J Chem 2018; 57:990-998. [PMID: 29335656 DOI: 10.1002/ijch.201700059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The iron(II) triflate complex (1) of 1,2-bis(2,2'-bipyridyl-6-yl)ethane, with two bipyridine moieties connected by an ethane bridge, was prepared. Addition of aqueous 30% H2O2 to an acetonitrile solution of 1 yielded 2, a green compound with λmax=710 nm. Moessbauer measurements on 2 showed a doublet with an isomer shift (δ) of 0.35 mm/s and a quadrupole splitting (ΔEQ) of 0.86 mm/s, indicative of an antiferromagnetically coupled diferric complex. Resonance Raman spectra showed peaks at 883, 556 and 451 cm-1 that downshifted to 832, 540 and 441 cm-1 when 1 was treated with H218O2. All the spectroscopic data support the initial formation of a (μ-hydroxo)(μ-1,2-peroxo)diiron(III) complex that oxidizes carbon-hydrogen bonds. At 0°C 2 reacted with cyclohexene to yield allylic oxidation products but not epoxide. Weak benzylic C-H bonds of alkylarenes were also oxidized. A plot of the logarithms of the second order rate constants versus the bond dissociation energies of the cleaved C-H bond showed an excellent linear correlation. Along with the observation that oxidation of the probe substrate 2,2-dimethyl-1-phenylpropan-1-ol yielded the corresponding ketone but no benzaldehyde, and the kinetic isotope effect, kH/kD , of 2.8 found for the oxidation of xanthene, the results support the hypothesis for a metal-based H-atom abstraction mechanism. Complex 2 is a rare example of a (μ-hydroxo)(μ-1,2-peroxo)diiron(III) complex that can elicit the oxidation of carbon-hydrogen bonds.
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Affiliation(s)
- Alexander M Khenkin
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel 76100, phone: +972-8-9343354
| | - Madhu Vedichi
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel 76100, phone: +972-8-9343354
| | - Linda J W Shimon
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Matthew A Cranswick
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA
| | - Johannes E M N Klein
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA
| | - Ronny Neumann
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel 76100, phone: +972-8-9343354
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23
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Jasniewski AJ, Komor AJ, Lipscomb JD, Que L. Unprecedented (μ-1,1-Peroxo)diferric Structure for the Ambiphilic Orange Peroxo Intermediate of the Nonheme N-Oxygenase CmlI. J Am Chem Soc 2017; 139:10472-10485. [PMID: 28673082 PMCID: PMC5568637 DOI: 10.1021/jacs.7b05389] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The final step in the biosynthesis of the antibiotic chloramphenicol is the oxidation of an aryl-amine substrate to an aryl-nitro product catalyzed by the N-oxygenase CmlI in three two-electron steps. The CmlI active site contains a diiron cluster ligated by three histidine and four glutamate residues and activates dioxygen to perform its role in the biosynthetic pathway. It was previously shown that the active oxidant used by CmlI to facilitate this chemistry is a peroxo-diferric intermediate (CmlIP). Spectroscopic characterization demonstrated that the peroxo binding geometry of CmlIP is not consistent with the μ-1,2 mode commonly observed in nonheme diiron systems. Its geometry was tentatively assigned as μ-η2:η1 based on comparison with resonance Raman (rR) features of mixed-metal model complexes in the absence of appropriate diiron models. Here, X-ray absorption spectroscopy (XAS) and rR studies have been used to establish a refined structure for the diferric cluster of CmlIP. The rR experiments carried out with isotopically labeled water identified the symmetric and asymmetric vibrations of an Fe-O-Fe unit in the active site at 485 and 780 cm-1, respectively, which was confirmed by the 1.83 Å Fe-O bond observed by XAS. In addition, a unique Fe···O scatterer at 2.82 Å observed from XAS analysis is assigned as arising from the distal O atom of a μ-1,1-peroxo ligand that is bound symmetrically between the irons. The (μ-oxo)(μ-1,1-peroxo)diferric core structure associated with CmlIP is unprecedented among diiron cluster-containing enzymes and corresponding biomimetic complexes. Importantly, it allows the peroxo-diferric intermediate to be ambiphilic, acting as an electrophilic oxidant in the initial N-hydroxylation of an arylamine and then becoming a nucleophilic oxidant in the final oxidation of an aryl-nitroso intermediate to the aryl-nitro product.
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Affiliation(s)
- Andrew J. Jasniewski
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
- Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455
| | - Anna J. Komor
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
- Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455
| | - John D. Lipscomb
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
- Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455
| | - Lawrence Que
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
- Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455
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24
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Ansari A, Ansari M, Singha A, Rajaraman G. Interplay of Electronic Cooperativity and Exchange Coupling in Regulating the Reactivity of Diiron(IV)-oxo Complexes towards C−H and O−H Bond Activation. Chemistry 2017; 23:10110-10125. [DOI: 10.1002/chem.201701059] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Azaj Ansari
- Department of Chemistry; CUH Haryana; Haryana 123031 India
| | | | - Asmita Singha
- Department of Chemistry; IIT Bombay; Mumbai 400076 India
| | - Gopalan Rajaraman
- Department of Chemistry; Indian Institute of Technology Bombay, Powai; Mumbai, Maharashtra 400076 India
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25
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26
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A growing family of O2 activating dinuclear iron enzymes with key catalytic diiron(III)-peroxo intermediates: Biological systems and chemical models. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2016.05.014] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Jasniewski AJ, Engstrom LM, Vu VV, Park MH, Que L. X-ray absorption spectroscopic characterization of the diferric-peroxo intermediate of human deoxyhypusine hydroxylase in the presence of its substrate eIF5a. J Biol Inorg Chem 2016; 21:605-18. [PMID: 27380180 PMCID: PMC4990465 DOI: 10.1007/s00775-016-1373-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 06/16/2016] [Indexed: 11/29/2022]
Abstract
Human deoxyhypusine hydroxylase (hDOHH) is an enzyme that is involved in the critical post-translational modification of the eukaryotic translation initiation factor 5A (eIF5A). Following the conversion of a lysine residue on eIF5A to deoxyhypusine (Dhp) by deoxyhypusine synthase, hDOHH hydroxylates Dhp to yield the unusual amino acid residue hypusine (Hpu), a modification that is essential for eIF5A to promote peptide synthesis at the ribosome, among other functions. Purification of hDOHH overexpressed in E. coli affords enzyme that is blue in color, a feature that has been associated with the presence of a peroxo-bridged diiron(III) active site. To gain further insight into the nature of the diiron site and how it may change as hDOHH goes through the catalytic cycle, we have conducted X-ray absorption spectroscopic studies of hDOHH on five samples that represent different species along its reaction pathway. Structural analysis of each species has been carried out, starting with the reduced diferrous state, proceeding through its O2 adduct, and ending with a diferric decay product. Our results show that the Fe⋯Fe distances found for the five samples fall within a narrow range of 3.4-3.5 Å, suggesting that hDOHH has a fairly constrained active site. This pattern differs significantly from what has been associated with canonical dioxygen activating nonheme diiron enzymes, such as soluble methane monooxygenase and Class 1A ribonucleotide reductases, for which the Fe⋯Fe distance can change by as much as 1 Å during the redox cycle. These results suggest that the O2 activation mechanism for hDOHH deviates somewhat from that associated with the canonical nonheme diiron enzymes, opening the door to new mechanistic possibilities for this intriguing family of enzymes.
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Affiliation(s)
- Andrew J Jasniewski
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Lisa M Engstrom
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
| | - Van V Vu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA
- NTT Hi-Tech Institute, Nguyen Tat Thanh University, 298-300A Nguyen Tat Thanh Street, Ward 13, District 4, Ho Chi Minh City, Vietnam
| | - Myung Hee Park
- National Institute of Dental and Craniofacial Research, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN, 55455, USA.
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28
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Bae JM, Lee MM, Lee SA, Lee SY, Bok KH, Kim J, Kim C. Nonheme iron complex-catalyzed efficient alcohol oxidation by t-BuOOH with N-hydroxyphthalimide (NHPI) as co-catalyst: Implication of high valent iron-oxo species. Inorganica Chim Acta 2016. [DOI: 10.1016/j.ica.2016.06.038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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29
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Szávuly MI, Surducan M, Nagy E, Surányi M, Speier G, Silaghi-Dumitrescu R, Kaizer J. Functional models of nonheme diiron enzymes: kinetic and computational evidence for the formation of oxoiron(iv) species from peroxo-diiron(iii) complexes, and their reactivity towards phenols and H2O2. Dalton Trans 2016; 45:14709-18. [PMID: 27283752 DOI: 10.1039/c6dt01598k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reactivity of the previously reported peroxo adducts [Fe2(μ-O2)(L(1))4(CH3CN)2](2+), and [Fe2(μ-O2)(L(2))4(CH3CN)2](2+), (L(1) = 2-(2'-pyridyl)benzimidazole and L(2) = 2-(2'-pyridyl)-N-methylbenzimidazole) towards H2O2 as catalase mimics, and towards various phenols as functional RNR-R2 mimics, is described. Kinetic, mechanistic and computational studies gave direct evidence for the involvement of the (μ-1,2-peroxo)diiron(iii) intermediate in the O-H activation process via formation of low-spin oxoiron(iv) species.
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Affiliation(s)
- Miklós István Szávuly
- Department of Chemistry, University of Pannonia, 8201 Veszprém, Wartha Vince u. 1., Hungary.
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30
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Sekino M, Furutachi H, Tasaki K, Ishikawa T, Mori S, Fujinami S, Akine S, Sakata Y, Nomura T, Ogura T, Kitagawa T, Suzuki M. New mechanistic insight into intramolecular arene hydroxylation initiated by (μ-1,2-peroxo)diiron(III) complexes with dinucleating ligands. Dalton Trans 2016; 45:469-73. [PMID: 26646073 DOI: 10.1039/c5dt04088d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
(μ-1,2-Peroxo)diiron(iii) complexes (-R) with dinucleating ligands (R-L) generated from the reaction of bis(μ-hydroxo)diiron(ii) complexes [Fe2(R-L)(OH)2](2+) (-R) with dioxygen in acetone at -20 °C provide a diiron-centred electrophilic oxidant, presumably diiron(iv)-oxo species, which is involved in aromatic ligand hydroxylation.
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Affiliation(s)
- Mio Sekino
- Department of Chemistry, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
| | - Hideki Furutachi
- Department of Chemistry, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
| | - Kyosuke Tasaki
- Department of Chemistry, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
| | - Takanao Ishikawa
- Department of Chemistry, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
| | - Shigeki Mori
- Department of Chemistry, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
| | - Shuhei Fujinami
- Department of Chemistry, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
| | - Shigehisa Akine
- Department of Chemistry, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
| | - Yoko Sakata
- Department of Chemistry, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
| | - Takashi Nomura
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, Ako-gun, Hyogo 678-1297, Japan
| | - Takashi Ogura
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, Ako-gun, Hyogo 678-1297, Japan
| | - Teizo Kitagawa
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, Ako-gun, Hyogo 678-1297, Japan
| | - Masatatsu Suzuki
- Department of Chemistry and Biochemistry, Graduate Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
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31
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Shokri A, Que L. Conversion of Aldehyde to Alkane by a Peroxoiron(III) Complex: A Functional Model for the Cyanobacterial Aldehyde-Deformylating Oxygenase. J Am Chem Soc 2015; 137:7686-91. [PMID: 26030345 DOI: 10.1021/jacs.5b01053] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cyanobacterial aldehyde-deformylating oxygenase (cADO) converts long-chain fatty aldehydes to alkanes via a proposed diferric-peroxo intermediate that carries out the oxidative deformylation of the substrate. Herein, we report that the synthetic iron(III)-peroxo complex [Fe(III)(η(2)-O2)(TMC)](+) (TMC = tetramethylcyclam) causes a similar transformation in the presence of a suitable H atom donor, thus serving as a functional model for cADO. Mechanistic studies suggest that the H atom donor can intercept the incipient alkyl radical formed in the oxidative deformylation step in competition with the oxygen rebound step typically used by most oxygenases for forming C-O bonds.
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Affiliation(s)
- Alireza Shokri
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
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32
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Jozwiuk A, Ingram AL, Powell DR, Moubaraki B, Chilton NF, Murray KS, Houser RP. Redox and acid-base properties of asymmetric non-heme (hydr)oxo-bridged diiron complexes. Dalton Trans 2015; 43:9740-53. [PMID: 24841725 DOI: 10.1039/c4dt00047a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The diiron unit is commonly found as the active site in enzymes that catalyze important biological transformations. Two μ-(hydr)oxo-diiron(iii) complexes with the ligands 2,2'-(2-methyl-2-(pyridine-2-yl)propane-1,3-diyl)bis(azanediyl)bis(methylene)diphenol (H2L) and 2,2'-(2-methyl-2(pyridine-2-yl)propane-1,3-diyl)bis(azanediyl)bis(methylene)bis(4-nitrophenol) (H2L(NO2)), namely [(FeL)2(μ-O)] () and [(FeL(NO2))2(μ-OH)]ClO4 () were synthesized and characterized. In the solid state, both structures are asymmetric, with unsupported (hydr)oxo bridges. Intramolecular hydrogen bonding of the ligand NH groups to the phenolate O atoms hold the diiron cores in a bent configuration (Fe-O-Fe angle of 143.7° for and 140.1° for ). A new phenolate bridged diferrous complex, [(FeL)2] (), was synthesized and characterized. Upon exposure to air the diferrous complex is oxidized to the diferric . Cyclic voltammetry at different scan rates and chemical reduction of [(FeL)2(μ-OH)]BPh4 () with cobaltocene revealed disproportionation followed by proton transfer, and a mixed-valence species could not be trapped. Subsequent exposure to molecular oxygen results in the formation of . Electrochemical studies of indicate easier reduction of the diiron(iii/iii) to the mixed-valence state than for . The protonation of by benzoic acid to form [(FeL)2(μ-OH)](+) only changes the Fe-O-Fe angle by 5° (from 143.7° to 138.6°), and the pKa of the hydroxo bridge is estimated to be about 20.4. We attribute this high pKa partly to stabilization of the benzoate by hydrogen bonding to the ligand's amine proton. Magnetic susceptibility studies on solid samples of and yielded values of the antiferromagnetic exchange coupling constants, J, for these S = 5/2 dimers of -13.1 cm(-1) and -87.5 cm(-1), respectively, typical of such unsupported hydroxo- and oxo-bridges.
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Affiliation(s)
- Anna Jozwiuk
- Department of Chemistry & Biochemistry, University of Oklahoma, Norman, OK 73019, USA
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33
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Makris TM, Vu VV, Meier KK, Komor AJ, Rivard BS, Münck E, Que L, Lipscomb JD. An unusual peroxo intermediate of the arylamine oxygenase of the chloramphenicol biosynthetic pathway. J Am Chem Soc 2015; 137:1608-17. [PMID: 25564306 PMCID: PMC4318726 DOI: 10.1021/ja511649n] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Streptomyces venezuelae CmlI catalyzes the six-electron oxygenation of the arylamine precursor of chloramphenicol in a nonribosomal peptide synthetase (NRPS)-based pathway to yield the nitroaryl group of the antibiotic. Optical, EPR, and Mössbauer studies show that the enzyme contains a nonheme dinuclear iron cluster. Addition of O(2) to the diferrous state of the cluster results in an exceptionally long-lived intermediate (t(1/2) = 3 h at 4 °C) that is assigned as a peroxodiferric species (CmlI-peroxo) based upon the observation of an (18)O(2)-sensitive resonance Raman (rR) vibration. CmlI-peroxo is spectroscopically distinct from the well characterized and commonly observed cis-μ-1,2-peroxo (μ-η(1):η(1)) intermediates of nonheme diiron enzymes. Specifically, it exhibits a blue-shifted broad absorption band around 500 nm and a rR spectrum with a ν(O-O) that is at least 60 cm(-1) lower in energy. Mössbauer studies of the peroxo state reveal a diferric cluster having iron sites with small quadrupole splittings and distinct isomer shifts (0.54 and 0.62 mm/s). Taken together, the spectroscopic comparisons clearly indicate that CmlI-peroxo does not have a μ-η(1):η(1)-peroxo ligand; we propose that a μ-η(1):η(2)-peroxo ligand accounts for its distinct spectroscopic properties. CmlI-peroxo reacts with a range of arylamine substrates by an apparent second-order process, indicating that CmlI-peroxo is the reactive species of the catalytic cycle. Efficient production of chloramphenicol from the free arylamine precursor suggests that CmlI catalyzes the ultimate step in the biosynthetic pathway and that the precursor is not bound to the NRPS during this step.
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Affiliation(s)
- Thomas M. Makris
- Department of Biochemistry, Molecular Biology, and
Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Center for Metals in Biocatalysis, University of
Minnesota, Minneapolis, MN 55455
| | - Van V. Vu
- Center for Metals in Biocatalysis, University of
Minnesota, Minneapolis, MN 55455
- Department of Chemistry, University of Minnesota, Minneapolis,
Minnesota 55455, United States
| | - Katlyn K. Meier
- Department of Chemistry, Carnegie Mellon University,
Pittsburgh, PA 15213, United States
| | - Anna J. Komor
- Center for Metals in Biocatalysis, University of
Minnesota, Minneapolis, MN 55455
- Department of Chemistry, University of Minnesota, Minneapolis,
Minnesota 55455, United States
| | - Brent S. Rivard
- Department of Biochemistry, Molecular Biology, and
Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Center for Metals in Biocatalysis, University of
Minnesota, Minneapolis, MN 55455
| | - Eckard Münck
- Department of Chemistry, Carnegie Mellon University,
Pittsburgh, PA 15213, United States
| | - Lawrence Que
- Center for Metals in Biocatalysis, University of
Minnesota, Minneapolis, MN 55455
- Department of Chemistry, University of Minnesota, Minneapolis,
Minnesota 55455, United States
| | - John D. Lipscomb
- Department of Biochemistry, Molecular Biology, and
Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Center for Metals in Biocatalysis, University of
Minnesota, Minneapolis, MN 55455
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34
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Codolà Z, Gómez L, Kleespies ST, Que L, Costas M, Lloret-Fillol J. Evidence for an oxygen evolving iron-oxo-cerium intermediate in iron-catalysed water oxidation. Nat Commun 2015; 6:5865. [PMID: 25609387 DOI: 10.1038/ncomms6865] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 11/17/2014] [Indexed: 02/08/2023] Open
Abstract
The non-haem iron complex α-[Fe(II)(CF3SO3)2(mcp)] (mcp=(N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)-1,2-cis-diaminocyclohexane) reacts with Ce(IV) to oxidize water to O2, representing an iron-based functional model for the oxygen evolving complex of photosystem II. Here we trap an intermediate, characterized by cryospray ionization high resolution mass spectrometry and resonance Raman spectroscopy, and formulated as [(mcp)Fe(IV)(O)(μ-O)Ce(IV)(NO3)3](+), the first example of a well-characterized inner-sphere complex to be formed in cerium(IV)-mediated water oxidation. The identification of this reactive Fe(IV)-O-Ce(IV) adduct may open new pathways to validate mechanistic notions of an analogous Mn(V)-O-Ca(II) unit in the oxygen evolving complex that is responsible for carrying out the key O-O bond forming step.
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Affiliation(s)
- Zoel Codolà
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain
| | - Laura Gómez
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St S.E., Minneapolis, Minnesota 55455, USA
| | - Scott T Kleespies
- Serveis Tècnics de Recerca (STR), Parc Cientific i Tecnològic, Universitat de Girona, 17003 Girona, Spain
| | - Lawrence Que
- Serveis Tècnics de Recerca (STR), Parc Cientific i Tecnològic, Universitat de Girona, 17003 Girona, Spain
| | - Miquel Costas
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain
| | - Julio Lloret-Fillol
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain
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35
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Abstract
In order to address how diverse metalloprotein active sites, in particular those containing iron and copper, guide O₂binding and activation processes to perform diverse functions, studies of synthetic models of the active sites have been performed. These studies have led to deep, fundamental chemical insights into how O₂coordinates to mono- and multinuclear Fe and Cu centers and is reduced to superoxo, peroxo, hydroperoxo, and, after O-O bond scission, oxo species relevant to proposed intermediates in catalysis. Recent advances in understanding the various factors that influence the course of O₂activation by Fe and Cu complexes are surveyed, with an emphasis on evaluating the structure, bonding, and reactivity of intermediates involved. The discussion is guided by an overarching mechanistic paradigm, with differences in detail due to the involvement of disparate metal ions, nuclearities, geometries, and supporting ligands providing a rich tapestry of reaction pathways by which O₂is activated at Fe and Cu sites.
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36
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Chalupský J, Rokob TA, Kurashige Y, Yanai T, Solomon EI, Rulíšek L, Srnec M. Reactivity of the binuclear non-heme iron active site of Δ⁹ desaturase studied by large-scale multireference ab initio calculations. J Am Chem Soc 2014; 136:15977-91. [PMID: 25313991 DOI: 10.1021/ja506934k] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The results of density matrix renormalization group complete active space self-consistent field (DMRG-CASSCF) and second-order perturbation theory (DMRG-CASPT2) calculations are presented on various structural alternatives for the O-O and first C-H activating step of the catalytic cycle of the binuclear nonheme iron enzyme Δ(9) desaturase. This enzyme is capable of inserting a double bond into an alkyl chain by double hydrogen (H) atom abstraction using molecular O2. The reaction step studied here is presumably associated with the highest activation barrier along the full pathway; therefore, its quantitative assessment is of key importance to the understanding of the catalysis. The DMRG approach allows unprecedentedly large active spaces for the explicit correlation of electrons in the large part of the chemically important valence space, which is apparently conditio sine qua non for obtaining well-converged reaction energetics. The derived reaction mechanism involves protonation of the previously characterized 1,2-μ peroxy Fe(III)Fe(III) (P) intermediate to a 1,1-μ hydroperoxy species, which abstracts an H atom from the C10 site of the substrate. An Fe(IV)-oxo unit is generated concomitantly, supposedly capable of the second H atom abstraction from C9. In addition, several popular DFT functionals were compared to the computed DMRG-CASPT2 data. Notably, many of these show a preference for heterolytic C-H cleavage, erroneously predicting substrate hydroxylation. This study shows that, despite its limitations, DMRG-CASPT2 is a significant methodological advancement toward the accurate computational treatment of complex bioinorganic systems, such as those with the highly open-shell diiron active sites.
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Affiliation(s)
- Jakub Chalupský
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , Flemingovo náměstí 2, 166 10 Praha 6, Czech Republic
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37
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Shin JW, Bae JM, Kim C, Min KS. Catalysis and molecular magnetism of dinuclear iron(III) complexes with N-(2-pyridylmethyl)-iminodiethanol/-ate. Dalton Trans 2014; 43:3999-4008. [PMID: 24452503 DOI: 10.1039/c3dt53376j] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction of N-(2-pyridylmethyl)iminodiethanol (H2pmide) and Fe(NO3)3·9H2O in MeOH led to the formation of a dimeric iron(III) complex, [(Hpmide)Fe(NO3)]2(NO3)2·2CH3OH (1). Its anion-exchanged form, [(pmide)Fe(N3)]2 (2), was prepared by the reaction of 1and NaN3 in MeOH, during which the Hpmide ligand of 1 was also deprotonated. These compounds were investigated by single crystal X-ray diffraction and magnetochemistry. In complex 1, one iron(III) ion was bonded with a mono-deprotonated Hpmide ligand and a nitrate ion. The two iron(III) ions within the dinuclear unit were connected by two ethoxy groups with an inversion center. In 2, one iron(III) ion was coordinated with a deprotonated pmide ligand and an azide ion. The Fe(pmide)(N3) unit was related by symmetry through an inversion center. Both 1 and 2 efficiently catalyzed the oxidation of a variety of alcohols under mild conditions. The oxidation mechanism was proposed to involve an Fe(IV)=O intermediate as the major reactive species and an Fe(V)=O intermediate as a minor oxidant. Evidence for this proposal was derived from reactivity and Hammett studies, KIE (kH/kD) values, and the use of MPPH (2-methyl-1-phenylprop-2-yl hydroperoxide) as a mechanistic probe. Both compounds had significant antiferromagnetic interactions between the iron(III) ions via the oxygen atoms. 1 showed a strong antiferromagnetic interaction within the Fe(III) dimer, while 2 had a weak antiferromagnetic coupling within the Fe(III) dimer.
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Affiliation(s)
- Jong Won Shin
- Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National University, Daegu, 702-701, Republic of Korea
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38
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Pap JS, Draksharapu A, Giorgi M, Browne WR, Kaizer J, Speier G. Stabilisation of μ-peroxido-bridged Fe(III) intermediates with non-symmetric bidentate N-donor ligands. Chem Commun (Camb) 2014; 50:1326-9. [PMID: 24343416 DOI: 10.1039/c3cc48196d] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The spectroscopic characterisation of the (μ-1,2-peroxido)diiron(iii) species formed transiently upon reaction of [Fe(ii)(NN)3](2+) complexes with H2O2 by UV/vis absorption and resonance Raman spectroscopy is reported. The intermediacy of such species in the disproportionation of H2O2 is demonstrated.
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Affiliation(s)
- József S Pap
- Department of Chemistry, University of Pannonia, H-8200 Veszprém, Hungary.
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39
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Stoian SA, Xue G, Bominaar EL, Que L, Münck E. Spectroscopic and theoretical investigation of a complex with an [O═Fe(IV)-O-Fe(IV)═O] core related to methane monooxygenase intermediate Q. J Am Chem Soc 2014; 136:1545-58. [PMID: 24380398 DOI: 10.1021/ja411376u] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Previous efforts to model the diiron(IV) intermediate Q of soluble methane monooxygenase have led to the synthesis of a diiron(IV) TPA complex, 2, with an O=Fe(IV)-O-Fe(IV)-OH core that has two ferromagnetically coupled Sloc = 1 sites. Addition of base to 2 at -85 °C elicits its conjugate base 6 with a novel O═Fe(IV)-O-Fe(IV)═O core. In frozen solution, 6 exists in two forms, 6a and 6b, that we have characterized extensively using Mössbauer and parallel mode EPR spectroscopy. The conversion between 2 and 6 is quantitative, but the relative proportions of 6a and 6b are solvent dependent. 6a has two equivalent high-spin (Sloc = 2) sites, which are antiferromagnetically coupled; its quadrupole splitting (0.52 mm/s) and isomer shift (0.14 mm/s) match those of intermediate Q. DFT calculations suggest that 6a assumes an anti conformation with a dihedral O═Fe-Fe═O angle of 180°. Mössbauer and EPR analyses show that 6b is a diiron(IV) complex with ferromagnetically coupled Sloc = 1 and Sloc = 2 sites to give total spin St = 3. Analysis of the zero-field splittings and magnetic hyperfine tensors suggests that the dihedral O═Fe-Fe═O angle of 6b is ∼90°. DFT calculations indicate that this angle is enforced by hydrogen bonding to both terminal oxo groups from a shared water molecule. The water molecule preorganizes 6b, facilitating protonation of one oxo group to regenerate 2, a protonation step difficult to achieve for mononuclear Fe(IV)═O complexes. Complex 6 represents an intriguing addition to the handful of diiron(IV) complexes that have been characterized.
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Affiliation(s)
- Sebastian A Stoian
- Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
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40
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Dassama LMK, Silakov A, Krest CM, Calixto JC, Krebs C, Bollinger JM, Green MT. A 2.8 Å Fe-Fe separation in the Fe2(III/IV) intermediate, X, from Escherichia coli ribonucleotide reductase. J Am Chem Soc 2013; 135:16758-61. [PMID: 24094084 DOI: 10.1021/ja407438p] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A class Ia ribonucleotide reductase (RNR) employs a μ-oxo-Fe2(III/III)/tyrosyl radical cofactor in its β subunit to oxidize a cysteine residue ~35 Å away in its α subunit; the resultant cysteine radical initiates substrate reduction. During self-assembly of the Escherichia coli RNR-β cofactor, reaction of the protein's Fe2(II/II) complex with O2 results in accumulation of an Fe2(III/IV) cluster, termed X, which oxidizes the adjacent tyrosine (Y122) to the radical (Y122(•)) as the cluster is converted to the μ-oxo-Fe2(III/III) product. As the first high-valent non-heme-iron enzyme complex to be identified and the key activating intermediate of class Ia RNRs, X has been the focus of intensive efforts to determine its structure. Initial characterization by extended X-ray absorption fine structure (EXAFS) spectroscopy yielded a Fe-Fe separation (d(Fe-Fe)) of 2.5 Å, which was interpreted to imply the presence of three single-atom bridges (O(2-), HO(-), and/or μ-1,1-carboxylates). This short distance has been irreconcilable with computational and synthetic models, which all have d(Fe-Fe) ≥ 2.7 Å. To resolve this conundrum, we revisited the EXAFS characterization of X. Assuming that samples containing increased concentrations of the intermediate would yield EXAFS data of improved quality, we applied our recently developed method of generating O2 in situ from chlorite using the enzyme chlorite dismutase to prepare X at ~2.0 mM, more than 2.5 times the concentration realized in the previous EXAFS study. The measured d(Fe-Fe) = 2.78 Å is fully consistent with computational models containing a (μ-oxo)2-Fe2(III/IV) core. Correction of the d(Fe-Fe) brings the experimental data and computational models into full conformity and informs analysis of the mechanism by which X generates Y122(•).
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Affiliation(s)
- Laura M K Dassama
- Departments of †Chemistry and ‡Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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41
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Pap JS, Cranswick MA, Balogh-Hergovich E, Baráth G, Giorgi M, Rohde GT, Kaizer J, Speier G, Que L. An Iron(II)(1,3-bis(2'-pyridylimino)isoindoline) Complex as a Catalyst for Substrate Oxidation with H 2O 2. Evidence for a Transient Peroxodiiron(III) Species. Eur J Inorg Chem 2013; 2013:3858-3866. [PMID: 24587695 PMCID: PMC3935335 DOI: 10.1002/ejic.201300162] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Indexed: 11/06/2022]
Abstract
The complex [Fe(indH)(solvent)3](ClO4)2 (1) has been isolated from the reaction of equimolar amounts of 1,3-bis(2'-pyridylimino)isoindoline (indH) and Fe(ClO4)2 in acetonitrile and characterized by X-ray crystallography and several spectroscopic techniques. It is a suitable catalyst for the oxidation of thioanisoles and benzyl alcohols with H2O2 as the oxidant. Hammett correlations and kinetic isotope effect experiments support the involvement of an electrophilic metal-based oxidant. A metastable green species (2) is observed when 1 is reacted with H2O2 at -40 °C, which has been characterized to have a FeIII(μ-O)(μ-O2)FeIII core on the basis of UV-Vis, electron paramagnetic resonance, resonance Raman, and X-ray absorption spectroscopic data.
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Affiliation(s)
- József S Pap
- Department of Chemistry, University of Pannonia, 8201 Veszprém, Wartha Vince u. 1., Hungary
| | - Matthew A Cranswick
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - E Balogh-Hergovich
- Department of Chemistry, University of Pannonia, 8201 Veszprém, Wartha Vince u. 1., Hungary
| | - Gábor Baráth
- Department of Chemistry, University of Pannonia, 8201 Veszprém, Wartha Vince u. 1., Hungary
| | - Michel Giorgi
- Aix-Marseille Université, FR1739, Spectropole, Campus St. Jérôme, Avenue Escadrille Normandie-Niemen, 13397 Marseille cedex 20, France
| | - Gregory T Rohde
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - József Kaizer
- Department of Chemistry, University of Pannonia, 8201 Veszprém, Wartha Vince u. 1., Hungary
| | - Gábor Speier
- Department of Chemistry, University of Pannonia, 8201 Veszprém, Wartha Vince u. 1., Hungary
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
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