1
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Quiroz M, Lockart MM, Saber MR, Vali SW, Elrod LC, Pierce BS, Hall MB, Darensbourg MY. Cooperative redox and spin activity from three redox congeners of sulfur-bridged iron nitrosyl and nickel dithiolene complexes. Proc Natl Acad Sci U S A 2022; 119:e2201240119. [PMID: 35696567 PMCID: PMC9233302 DOI: 10.1073/pnas.2201240119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 05/06/2022] [Indexed: 12/15/2022] Open
Abstract
The synthesis of sulfur-bridged Fe-Ni heterobimetallics was inspired by Nature's strategies to "trick" abundant first row transition metals into enabling 2-electron processes: redox-active ligands (including pendant iron-sulfur clusters) and proximal metals. Our design to have redox-active ligands on each metal, NO on iron and dithiolene on nickel, resulted in the observation of unexpectedly intricate physical properties. The metallodithiolate, (NO)Fe(N2S2), reacts with a labile ligand derivative of [NiII(S2C2Ph2)]0, NiDT, yielding the expected S-bridged neutral adduct, FeNi, containing a doublet {Fe(NO)}7. Good reversibility of two redox events of FeNi led to isolation of reduced and oxidized congeners. Characterization by various spectroscopies and single-crystal X-ray diffraction concluded that reduction of the FeNi parent yielded [FeNi]-, a rare example of a high-spin {Fe(NO)}8, described as linear FeII(NO-). Mössbauer data is diagnostic for the redox change at the {Fe(NO)}7/8 site. Oxidation of FeNi generated the 2[FeNi]+⇌[Fe2Ni2]2+ equilibrium in solution; crystallization yields only the [Fe2Ni2]2+ dimer, isolated as PF6- and BArF- salts. The monomer is a spin-coupled diradical between {Fe(NO)}7 and NiDT+, while dimerization couples the two NiDT+ via a Ni2S2 rhomb. Magnetic susceptibility studies on the dimer found a singlet ground state with a thermally accessible triplet excited state responsible for the magnetism at 300 K (χMT = 0.67 emu·K·mol-1, µeff = 2.31 µB), and detectable by parallel-mode EPR spectroscopy at 20 to 50 K. A theoretical model built on an H4 chain explains this unexpected low energy triplet state arising from a combination of anti- and ferromagnetic coupling of a four-radical molecular conglomerate.
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Affiliation(s)
- Manuel Quiroz
- Department of Chemistry, Texas A&M University, College Station, TX 77843
| | - Molly M. Lockart
- Department of Chemistry & Biochemistry, Samford University, Birmingham, AL 35229
| | - Mohamed R. Saber
- Chemistry Department, Faculty of Science, Fayoum University, Fayoum 63514, Egypt
| | - Shaik Waseem Vali
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77845
| | - Lindy C. Elrod
- Department of Chemistry, Texas A&M University, College Station, TX 77843
| | - Brad S. Pierce
- Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, AL 35487
| | - Michael B. Hall
- Department of Chemistry, Texas A&M University, College Station, TX 77843
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Wu T, Wang S, Lv Y, Fu T, Jiang J, Lu X, Yu ZP, zhang J, Wang L, Zhou HP. A New Bis(thioether)-Dipyrrin N2S2 Ligand and Its Coordination Behaviors to Nickel, Copper and Zinc. Dalton Trans 2022; 51:9699-9707. [DOI: 10.1039/d2dt01282k] [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
Tetradentate N2S2 coordination platforms are widespread in biological system and have endowed the metalloenzymes and metalloproteins with abundant reactivities and functions. However, there have only three types of N2S2 scaffolds...
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3
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Panda C, Sarkar A, Sen Gupta S. Coordination chemistry of carboxamide ‘Nx’ ligands to metal ions for bio-inspired catalysis. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213314] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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4
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Gordon JB, McGale JP, Prendergast JR, Shirani-Sarmazeh Z, Siegler MA, Jameson GNL, Goldberg DP. Structures, Spectroscopic Properties, and Dioxygen Reactivity of 5- and 6-Coordinate Nonheme Iron(II) Complexes: A Combined Enzyme/Model Study of Thiol Dioxygenases. J Am Chem Soc 2018; 140:14807-14822. [PMID: 30346746 PMCID: PMC6596423 DOI: 10.1021/jacs.8b08349] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The synthesis of four new FeII(N4S(thiolate)) complexes as models of the thiol dioxygenases are described. They are composed of derivatives of the neutral, tridentate ligand triazacyclononane (R3TACN; R = Me, iPr) and 2-aminobenzenethiolate (abtx; X = H, CF3), a non-native substrate for thiol dioxygenases. The coordination number of these complexes depends on the identity of the TACN derivative, giving 6-coordinate (6-coord) complexes for FeII(Me3TACN)(abtx)(OTf) (1: X = H; 2: X = CF3) and 5-coordinate (5-coord) complexes for [FeII(iPr3TACN)(abtx)](OTf) (3: X = H; 4: X = CF3). Complexes 1-4 were examined by UV-vis, 1H/19F NMR, and Mössbauer spectroscopies, and density functional theory (DFT) calculations were employed to support the data. Mössbauer spectroscopy reveals that the 6-coord 1-2 and 5-coord 3- 4 exhibit distinct spectra, and these data are compared with that for cysteine-bound CDO, helping to clarify the coordination environment of the cys-bound FeII active site. Reaction of 1 or 2 with O2 at -95 °C leads to S-oxygenation of the abt ligand, and in the case of 2, a rare di(sulfinato)-bridged complex, [Fe2III(μ-O)((2-NH2) p-CF3C6H3SO2)2](OTf)2 ( 5), was obtained. Parallel enzymatic studies on the CDO variant C93G were carried out with the abt substrate and show that reaction with O2 leads to disulfide formation, as opposed to S-oxygenation. The combined model and enzyme studies show that the thiol dioxygenases can operate via a 6-coord FeII center, in contrast to the accepted mechanism for nonheme iron dioxygenases, and that proper substrate chelation to Fe appears to be critical for S-oxygenation.
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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
- School of Chemistry , Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne , 30 Flemington Road , Parkville , Victoria 3010 , Australia
| | - Jeremy P McGale
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
- School of Chemistry , Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne , 30 Flemington Road , Parkville , Victoria 3010 , Australia
| | - Joshua R Prendergast
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
- School of Chemistry , Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne , 30 Flemington Road , Parkville , Victoria 3010 , Australia
| | - Zahra Shirani-Sarmazeh
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
- School of Chemistry , Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne , 30 Flemington Road , Parkville , Victoria 3010 , Australia
| | - Maxime A Siegler
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
- School of Chemistry , Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne , 30 Flemington Road , Parkville , Victoria 3010 , Australia
| | - Guy N L Jameson
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
- School of Chemistry , Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne , 30 Flemington Road , Parkville , Victoria 3010 , Australia
| | - David P Goldberg
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
- School of Chemistry , Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne , 30 Flemington Road , Parkville , Victoria 3010 , Australia
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5
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Dey A, Confer AM, Vilbert AC, Moënne-Loccoz P, Lancaster KM, Goldberg DP. A Nonheme Sulfur-Ligated {FeNO} 6 Complex and Comparison with Redox-Interconvertible {FeNO} 7 and {FeNO} 8 Analogues. Angew Chem Int Ed Engl 2018; 57:13465-13469. [PMID: 30125450 DOI: 10.1002/anie.201806146] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Indexed: 01/23/2023]
Abstract
A nonheme {FeNO}6 complex, [Fe(NO)(N3PyS)]2+ , was synthesized by reversible, one-electron oxidation of an {FeNO}7 analogue. This complex completes the first known series of sulfur-ligated {FeNO}6-8 complexes. All three {FeNO}6-8 complexes are readily interconverted by one-electron oxidation/reduction. A comparison of spectroscopic data (UV/Vis, NMR, IR, Mössbauer, X-ray absorption) provides a complete picture of the electronic and structural changes that occur upon {FeNO}6 -{FeNO}8 interconversion. Dissociation of NO from the new {FeNO}6 complex is shown to be controlled by solvent, temperature, and photolysis, which is rare for a sulfur-ligated {FeNO}6 species.
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Affiliation(s)
- Aniruddha Dey
- Department of Chemistry, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Alex M Confer
- Department of Chemistry, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Avery C Vilbert
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Pierre Moënne-Loccoz
- Division of Environmental and Biomolecular Systems, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University, Baltimore, MD, 21218, USA
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6
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Dey A, Confer AM, Vilbert AC, Moënne‐Loccoz P, Lancaster KM, Goldberg DP. A Nonheme Sulfur‐Ligated {FeNO}
6
Complex and Comparison with Redox‐Interconvertible {FeNO}
7
and {FeNO}
8
Analogues. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201806146] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Aniruddha Dey
- Department of Chemistry The Johns Hopkins University Baltimore MD 21218 USA
| | - Alex M. Confer
- Department of Chemistry The Johns Hopkins University Baltimore MD 21218 USA
| | - Avery C. Vilbert
- Department of Chemistry and Chemical Biology Cornell University Ithaca NY 14853 USA
| | - Pierre Moënne‐Loccoz
- Division of Environmental and Biomolecular Systems Oregon Health and Science University Portland OR 97239 USA
| | - Kyle M. Lancaster
- Department of Chemistry and Chemical Biology Cornell University Ithaca NY 14853 USA
| | - David P. Goldberg
- Department of Chemistry The Johns Hopkins University Baltimore MD 21218 USA
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7
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Tyagi N, Singh O, Singh UP, Ghosh K. Nitric oxide (NO) reactivity studies on mononuclear iron(ii) complexes supported by a tetradentate Schiff base ligand. RSC Adv 2016. [DOI: 10.1039/c6ra21659e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mononuclear iron(ii) complexes were synthesised and characterized from tetradentate ligands. The reactivity of NO afforded ligand nitrated iron(ii) complex along with the in situ formation of an unstable nitrosylated iron complex which was monitored by UV-vis spectroscopy.
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Affiliation(s)
- Nidhi Tyagi
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee 247667
- India
| | - Ovender Singh
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee 247667
- India
| | - Udai P. Singh
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee 247667
- India
| | - Kaushik Ghosh
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee 247667
- India
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8
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Yadav S, Kumar S, Gupta R. Manganese Complexes of Pyrrole‐ and Indolecarboxamide Ligands: Synthesis, Structure, Electrochemistry, and Applications in Oxidative and Lewis‐Acid‐Assisted Catalysis. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500773] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sunil Yadav
- Department of Chemistry, University of Delhi, Delhi 110007, India, http://people.du.ac.in/~rgupta/
| | - Sushil Kumar
- Department of Chemistry, University of Delhi, Delhi 110007, India, http://people.du.ac.in/~rgupta/
| | - Rajeev Gupta
- Department of Chemistry, University of Delhi, Delhi 110007, India, http://people.du.ac.in/~rgupta/
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9
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Denny JA, Darensbourg MY. Metallodithiolates as ligands in coordination, bioinorganic, and organometallic chemistry. Chem Rev 2015; 115:5248-73. [PMID: 25948147 DOI: 10.1021/cr500659u] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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10
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Warner DS, Limberg C, Mebs S. Synthesis of a Chiral, Polydentate Ligand System Setting Out fromL-Cysteine and First Nickel Complexes Thereof. Z Anorg Allg Chem 2013. [DOI: 10.1002/zaac.201300071] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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11
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Abstract
The S-oxygenation of cysteine with dioxygen to give cysteine sulfinic acid occurs at the non-heme iron active site of cysteine dioxygenase. Similar S-oxygenation events occur in other non-heme iron enzymes, including nitrile hydratase and isopenicillin N synthase, and these enzymes have inspired the development of a class of [N(x)S(y)]-Fe model complexes. Certain members of this class have provided some intriguing examples of S-oxygenation, and this article summarizes these results, focusing on the non-heme iron(II/III)-thiolate model complexes that are known to react with O(2) or other O-atom transfer oxidants to yield sulfur oxygenates. Key aspects of the synthesis, structure, and reactivity of these systems are presented, along with any mechanistic information available on the oxygenation reactions. A number of iron(III)-thiolate complexes react with O(2) to give S-oxygenates, and the degree to which the thiolate sulfur donors are oxidized varies among the different complexes, depending upon the nature of the ligand, metal geometry, and spin state. The first examples of iron(II)-thiolate complexes that react with O(2) to give selective S-oxygenation are just emerging. Mechanistic information on these transformations is limited, with isotope labeling studies providing much of the current mechanistic data. The many questions that remain unanswered for both models and enzymes provide strong motivation for future work in this area.
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Affiliation(s)
- Alison C. McQuilken
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - David P. Goldberg
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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12
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Jayarathne U, Williams K, Kasyanenko VM, Mague JT, Rubtsov IV, Donahue JP. Structural characterization of [Fe(NO)(mnt)2]1−/2− salts. Polyhedron 2012. [DOI: 10.1016/j.poly.2011.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Surawatanawong P, Sproules S, Neese F, Wieghardt K. Electronic Structures and Spectroscopy of the Electron Transfer Series [Fe(NO)L2]z (z = 1+, 0, 1–, 2–,3–; L = Dithiolene). Inorg Chem 2011; 50:12064-74. [DOI: 10.1021/ic201565d] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Panida Surawatanawong
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Stephen Sproules
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
- EPSRC National UK EPR Facility and Service, Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Frank Neese
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
- Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstrasse 12, D-53115 Bonn, Germany
| | - Karl Wieghardt
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
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14
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Desbenoît N, Galardon E, Frapart Y, Tomas A, Artaud I. Reductive metalation of cyclic and acyclic pseudopeptidic bis-disulfides and back conversion of the resulting diamidato/dithiolato complexes to bis-disulfides. Inorg Chem 2011; 49:8637-44. [PMID: 20718487 DOI: 10.1021/ic101148c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyclic and acyclic pseudopeptidic bis-disulfides built on an o-phenylene diamine scaffold were prepared: (N(2)H(2)S(2))(2), 1a, N(2)H(2)(S-SCH(3))(2), 1b, and N(2)H(2)(S-StBu)(2), 1c. Reductive metalation of these disulfides with (PF(6))[Cu(CH(3)CN)(4)] in the presence of Et(4)NOH as a base, or with (Et(4)N)[Fe(SEt)(4)] and Et(4)NCl, yields the corresponding diamidato/dithiolato copper(III) or iron(III) complex, (Et(4)N)[Cu(N(2)S(2))], 2, or (Et(4)N)(2)[Fe(N(2)S(2))Cl], 5. These complexes display characteristics similar to those previously described in the literature. The mechanism of the metalation with copper has been investigated by X-band electron paramagnetic resonance (EPR) spectroscopy at 10 K. After metalation of the bis-disulfide 1c and deprotonation of the amide nitrogens, the reductive cleavage of the S-S bonds occurs by two one-electron transfers leading to the intermediate formation of a copper(II) complex and a thyil radical. Complexes 2 and 5 can be converted back to the cyclic bis-disulfide 1a with iodine in an 80% yield. Reaction of 5 with iodine in the presence of CH(3)S-SCH(3) affords a 1/1 mixture of the acyclic N(2)H(2)(S-SCH(3))(2) disulfide 1b and cyclic bis-disulfide 1a. From 2, the reaction was monitored by (1)H NMR and gives 1b as major product. While there is no reaction of 2 or 5 with tBuS-StBu and iodine, reaction with an excess of tBuSI affords quantitatively the di-tert-butyl disulfide 1c. To assess the role of the Cu(III) oxidation state, control experiments were carried out under strictly anaerobic conditions with the copper(II) complex, (Et(4)N)(2)[Cu(N(2)S(2))], 6. Complex 6 is oxidized to 2 by iodine, and it reacts with an excess of tBuSI, yielding 1c as final product, through the intermediate formation of complex 2.
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Affiliation(s)
- Nicolas Desbenoît
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université Paris Descartes, UMR 8601, CNRS, 45 rue des Saints Pères, 75270 Paris Cedex 06, France
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16
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Wang R, Wang X, Sundberg EB, Nguyen P, Grant GPG, Sheth C, Zhao Q, Herron S, Kantardjieff KA, Li L. Synthesis, structures, spectroscopic and electrochemical properties of dinitrosyl iron complexes with bipyridine, terpyridine, and 1,10-phenathroline. Inorg Chem 2010; 48:9779-85. [PMID: 19769382 DOI: 10.1021/ic901368t] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Three new dinitrosyl iron complexes LFe(NO)(2) (L = 2,2'-bipyridine (bipy) (1), 2,2',2''-terpyridine (terpy) (2) and 1,10-phenathroline (phen) (3)) were synthesized by the reaction of Fe(NO)(2)(CO)(2) with corresponding ligands in tetrahydrofuran. Complexes 1-3 were studied using IR, UV-vis, MS, NMR, and electrochemical techniques. Complexes 1 and 2 were also characterized using single crystal X-ray diffraction analysis. IR spectra of complexes 1-3 display two strong characteristic NO stretching frequencies (nu(NO)) in the region reflecting donor properties of the ligands. Cyclic voltammetry studies show two quasi-reversible one-electron reductions for all complexes. Electrochemical investigations using different concentrations show that an irreversible one-electron reduction at -1.85 V for complex 2 and -1.80 V for complex 3 are from solvated species. Single-crystal X-ray structural analysis reveals that complex 1 crystallizes in the triclinic P1 space group and the asymmetric unit consists of one Fe(NO)(2)(bipy) molecule with the two NO groups located on two sides of Fe(bipy) plane. Complex 2 crystallizes in monoclinic P21/n space group, and the asymmetric unit contains one Fe(NO)(2)(terpy) molecule, in which the NO groups are located on two sides of the plane consisted of Fe and two coordinated pyridyl rings, but almost parallel to the uncoordinated pyridyl ring. The crystal packings of both complexes 1 and 2 show intermolecular H-bonding and strong pi-pi stacking interactions.
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Affiliation(s)
- Rongming Wang
- Department of Chemistry and Biochemistry, California State University, Long Beach, California 90840, USA
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17
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Rose MJ, Betterley NM, Oliver AG, Mascharak PK. Binding of Nitric Oxide to a Synthetic Model of Iron-Containing Nitrile Hydratase (Fe-NHase) and Its Photorelease: Relevance to Photoregulation of Fe-NHase by NO. Inorg Chem 2010; 49:1854-64. [DOI: 10.1021/ic902220a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Michael J. Rose
- Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, California 95064
| | - Nolan M. Betterley
- Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, California 95064
| | - Allen G. Oliver
- Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, California 95064
| | - Pradip K. Mascharak
- Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, California 95064
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18
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Hsieh CC, Chao WJ, Horng YC. An unique stair-like infinite chain polymer containing dimeric N2S3 square-pyramidal iron(III) complex. INORG CHEM COMMUN 2009. [DOI: 10.1016/j.inoche.2009.06.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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Desbenoit N, Galardon E, Roussel P, Artaud I, Tomas A. Influence of carboxamido nitrogen donors on the redox potential of copper(III) complexes. J COORD CHEM 2009. [DOI: 10.1080/00958970902855614] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Nicolas Desbenoit
- a Faculté de pharmacie, Laboratoire de Cristallographie et RMN biologiques , UMR 8015 CNRS Université Paris Descartes , 4 avenue de l’Observatoire, 75005 Paris, France
- b Faculté de médecine, Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques , UMR 8601 CNRS Université Paris Descartes , 45 rue des Saints Pères, 75006 Paris, France
| | - Erwan Galardon
- b Faculté de médecine, Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques , UMR 8601 CNRS Université Paris Descartes , 45 rue des Saints Pères, 75006 Paris, France
| | - Pascal Roussel
- c Unité de Catalyse et Chimie du Solide, UMR 8181 CNRS, Ecole Nationale Supérieure de Chimie de Lille , BP 108, 59652 Villeneuve d’Ascq Cedex, France
| | - Isabelle Artaud
- b Faculté de médecine, Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques , UMR 8601 CNRS Université Paris Descartes , 45 rue des Saints Pères, 75006 Paris, France
| | - Alain Tomas
- a Faculté de pharmacie, Laboratoire de Cristallographie et RMN biologiques , UMR 8015 CNRS Université Paris Descartes , 4 avenue de l’Observatoire, 75005 Paris, France
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20
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Rose MJ, Betterley NM, Mascharak PK. Thiolate S-Oxygenation Controls Nitric Oxide (NO) Photolability of a Synthetic Iron Nitrile Hydratase (Fe-NHase) Model Derived from Mixed Carboxamide/Thiolate Ligand. J Am Chem Soc 2009; 131:8340-1. [DOI: 10.1021/ja9004656] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael J. Rose
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 96064
| | - Nolan M. Betterley
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 96064
| | - Pradip K. Mascharak
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 96064
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21
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Polynuclear 3d complexes based on potentially tetra-anionic heptadentate ligands including amido, amino and phenoxo donors: Synthesis, crystal structure and magnetic properties. Polyhedron 2007. [DOI: 10.1016/j.poly.2007.03.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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22
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Electronic structure of dinuclear iron nitrosyl complexes with different ligands at two iron centers. Polyhedron 2007. [DOI: 10.1016/j.poly.2007.03.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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23
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Bourlès E, Alves de Sousa R, Galardon E, Selkti M, Tomas A, Artaud I. Synthesis of cyclic mono- and bis-disulfides and their selective conversion to mono- and bis-thiosulfinates. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.01.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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24
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Ghosh P, Stobie K, Bill E, Bothe E, Weyhermüller T, Ward MD, McCleverty JA, Wieghardt K. Electronic Structure of Nitric Oxide Adducts of Bis(diaryl-1,2-dithiolene)iron Compounds: Four-Membered Electron-Transfer Series [Fe(NO)(L)2]z (z = 1+, 0, 1−, 2−). Inorg Chem 2006; 46:522-32. [PMID: 17279832 DOI: 10.1021/ic061874a] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Four members of the electron-transfer series [Fe(NO)(S(2)C(2)R(2))2]z (z = 1+, 0, 1-, 2-) have been isolated as solid materials (R = p-tolyl): [1a](BF4), [1a]0, [Co(Cp)2][1a], and [Co(Cp)2]2[1a]. In addition, complexes [2a]0 (R = 4,4-diphenyl), [3a]0 (R = p-methoxyphenyl), [Et(4)N][4a] (R = phenyl), and [PPh(4)][5a] (R = -CN) have been synthesized and the members of each of their electron-transfer series electrochemically generated in CH(2)Cl(2) solution. All species have been characterized electro- and magnetochemically. Their electronic, Mössbauer, and electron paramagnetic resonance spectra as well as their infrared spectra have been recorded in order to elucidate the electronic structure of each member of the electron-transfer series. It is shown that the monocationic, neutral, and monoanionic species possess an {FeNO}6 (S = 0) moiety where the redox chemistry is sulfur ligand-based, (L)2-(L*)1-: [Fe(NO)(L*)2]+ (S = 0), [Fe(NO)(L*)(L)]0 <--> [Fe(NO)(L)(L*)]0 (S = 1/2), [Fe(NO)(L)2]- (S = 0). Further one-electron reduction generates a dianion with an {FeNO}7 (S = 1/2) unit and two fully reduced, diamagnetic dianions L2-: [Fe(NO)(L)2]2- (S = 1/2).
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Affiliation(s)
- Prasanta Ghosh
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
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25
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Yano T, Arii H, Yamaguchi S, Funahashi Y, Jitsukawa K, Ozawa T, Masuda H. CoIII Complexes with Square-Planar N2S2- and N2(SO2)2-Type Ligands as An Active Site Structural Model for Nitrile Hydratase – Biological Implications of an Amidate Coordination. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200600507] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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26
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Kinetics and mechanism of the formation of (1,8)bis(2-hydroxybenzamido)3,6-diazaoctaneiron(III) and its reactions with thiocyanate, azide, acetate, sulfur(IV) and ascorbic acid in solution, and the synthesis and characterization of a novel oxo bridged diiron(III) complex. The role of phenol–amide–amine coordination. TRANSIT METAL CHEM 2006. [DOI: 10.1007/s11243-006-0079-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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27
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Harrop TC, Olmstead MM, Mascharak PK. Unusual role of solvents in the syntheses of {Fe-NO}6,7 nitrosyls derived from a ligand with carboxamido nitrogen and thiolato sulfur donors. Inorg Chem 2006; 44:6918-20. [PMID: 16180848 DOI: 10.1021/ic050659b] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reaction of excess NO with the S = 3/2 Fe(III) complex (Et4N)2[Fe(PhPepS)(Cl)] (1) in protic solvents such as MeOH affords the {Fe-NO}(7) nitrosyl (Et(4)N)(2)[Fe(PhPepS)(NO)] (2). This distorted square-pyramidal S = 1/2 complex, a product of reductive nitrosylation, is the first example of an {Fe-NO}7 nitrosyl with carboxamido-N and thiolato-S coordination. When the same reaction is performed in aprotic solvents such as MeCN and DMF, the product is a dimeric diamagnetic {Fe-NO}6 complex, (Et4N)2-[{Fe(PhPepS)(NO)}2] (3). Both electrochemical and chemical oxidation of 2 leads to the formation of 3 via a transient five-coordinate {Fe-NO}6 intermediate. The oxidation is NO-centered. The ligand frame is not attacked by excess NO in these reactions.
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Affiliation(s)
- Todd C Harrop
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, 95064, USA
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28
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Greene SN, Richards NGJ. Electronic structure, bonding, spectroscopy and energetics of Fe-dependent nitrile hydratase active-site models. Inorg Chem 2006; 45:17-36. [PMID: 16390037 DOI: 10.1021/ic050965p] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fe-type nitrile hydratase (NHase) is a non-heme Fe(III)-dependent enzyme that catalyzes the hydration of nitriles to the corresponding amides. Despite experimental studies of the enzyme and model Fe(III)-containing complexes, many questions concerning the electronic structure and spectroscopic transitions of the metal center remain unanswered. In addition, the catalytic mechanism of nitrile hydration has not yet been determined. We now report density functional theory (B3LYP/6-31G) calculations on three models of the Fe(III) center in the active site of NHase corresponding to hypothetical intermediates in the enzyme-catalyzed hydration of acetonitrile. Together with natural bond orbital (NBO) analysis of the chemical bonding in these active-site models and INDO/S CIS calculations of their electronic spectra, this theoretical investigation gives new insight into the molecular origin of the unusual low-spin preference and spectroscopic properties of the Fe(III) center. In addition, the low-energy electronic transition observed for the active form of NHase is assigned to a dd transition that is coupled with charge-transfer transitions involving the metal and its sulfur ligands. Calculations of isodesmic ligand-exchange reaction energies provide support for coordination of the Fe(III) center in free NHase by a water molecule rather than a hydroxide ion and suggest that the activation of the nitrile substrate by binding to the metal in the sixth coordination site during catalytic turnover cannot yet be definitively ruled out.
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Affiliation(s)
- Shannon N Greene
- Department of Chemistry, University of Florida, Gainesville, 32611-7200, USA
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29
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Chiang CY, Lee J, Dalrymple C, Sarahan MC, Reibenspies JH, Darensbourg MY. Synthesis and molecular structures of mononitrosyl (N2S2)M(NO) complexes (M = Fe, Co). Inorg Chem 2006; 44:9007-16. [PMID: 16296856 DOI: 10.1021/ic051027s] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of tetragonally distorted square pyramids of formula N2S2M(NO) (M = Fe, Co) is prepared and characterized by nu(NO) IR and EPR spectroscopies, magnetism and electrochemical properties, as well as solid-state crystal structure determinations. While the nu(NO) IR frequencies and the angleM-N-O angles indicate differences in the electronic environment of NO consistent with the Enemark-Feltham notation of [Fe(NO)]7 and [Co(NO)]8, the reduction potentials, assigned to [Fe(NO)]7 + e- <==> [Fe(NO)]8 and [Co(NO)]8 + e- <==> [Co(NO)]9 respectively, are very similar, and in cases identical, for most members of the series. Coupled with the potential for the M(NO) units to breathe out of and into the N2S2 core plane are unique S-M-N-O torsional arrangements and concomitant pi-bonding interactions which may account for the unusual coherence of reduction potentials within the series.
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Affiliation(s)
- Chao-Yi Chiang
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
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30
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Jaworska M. DFT calculations for model diimine-iron complexes with nitric oxide and water ligands. INORG CHEM COMMUN 2006. [DOI: 10.1016/j.inoche.2005.11.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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31
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Harrop TC, Olmstead MM, Mascharak PK. Modeling the Active Site of Nitrile Hydratase: Synthetic Strategies to Ensure Simultaneous Coordination of Carboxamido-N and Thiolato-S to Fe(III) Centers. Inorg Chem 2005; 44:9527-33. [PMID: 16323940 DOI: 10.1021/ic051183z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A general strategy for synthesizing Fe(III) complexes of ligands containing carboxamido-N and thiolato-S donors has been described. Reaction of the doubly deprotonated ligand PyPepS2- (where PyPepSH2=N-2-mercaptophenyl-2'-pyridinecarboxamide) with Fe(III) salts in DMF had previously afforded the Fe(III) complex (Et4N)[Fe(PyPepS)2] without any problem(s) associated with autoredox reactions of the thiolate functionality. In the present work, similar reactions with the doubly deprotonated ligand PiPepS2- (where PiPepSH2=2-mercapto-N-pyridin-2-yl-methylbenzamide) with Fe(III) salts, however, fail to afford any Fe(III) complex because of autoredox reactions. The break in the conjugation in the PiPepSH2 ligand frame is the key reason for this difference in behavior between these two very similar ligands. This is demonstrated by the fact that the same reaction with AqPepS2- (where AqPepSH2=2-mercapto-N-quinolin-8-yl-benzamide), another ligand with extended conjugation, affords the Fe(III) complex (Et4N)[Fe(AqPepS)2] without any synthetic complication. It is therefore evident that ligands in which the carboxamide and thiolate functionalities are kept in conjugation could be used to isolate Fe(III) complexes with carboxamido-N and thiolato-S coordination. This finding will be very helpful in future research work in the area of modeling the active site of Fe-containing nitrile hydratase.
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Affiliation(s)
- Todd C Harrop
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
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32
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Nayak S, Dash AC, Nayak PK, Das D. Kinetics and Mechanism of the Formation of (1,5)bis(2-hydroxybenzamido)3- azapentaneiron(III) and its Reactions with Thiocyanate, Azide, Acetate, Sulfur(IV) and Ascorbic Acid in Solution, and the Synthesis and Characterization of (nitrato)bis- (2-hydroxybenzamido)3-azapentaneiron(III). The Role of Phenol–amide–amine Coordination. TRANSIT METAL CHEM 2005. [DOI: 10.1007/s11243-005-5627-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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33
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New precursor for the post-synthesis preparation of Fe-ZSM-5 zeolites with low iron content. Catal Letters 2005. [DOI: 10.1007/s10562-005-6500-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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34
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Alves de Sousa R, Galardon E, Rat M, Giorgi M, Artaud I. Oxidation of Zn(N2S2) complexes to disulfonates: relevance to zinc-finger oxidation under oxidative stress. J Inorg Biochem 2005; 99:690-7. [PMID: 15708789 DOI: 10.1016/j.jinorgbio.2004.11.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Revised: 11/12/2004] [Accepted: 11/19/2004] [Indexed: 10/25/2022]
Abstract
A series of Zn(N2S2) complexes has been prepared, and characterized. They have different nitrogen donors such as, either two amidates, two amines, two imines or one amidate and one imine. A bis-amidato dithiolato complex has been structurally characterized by single crystal X-ray diffraction analysis, and exhibits a distorted tetrahedral structure. Oxidation of all these complexes with dioxirane or anhydrous H2O2 results in the formation of a unique product, the disulfonate species. Most often, zinc was found to be released during the course of the oxidation. The bis-imine/bis-sulfonate species is the only one to retain zinc. This complex was crystallized with two pyridine molecules. Its crystal structure reveals a distorted octahedral environment around the zinc cation.
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Affiliation(s)
- Rodolphe Alves de Sousa
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601 CNRS, Université René Descartes, 45 rue des Sts Pères, 75270 Paris Cedex 06, France
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35
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Afshar RK, Patra AK, Olmstead MM, Mascharak PK. Syntheses, Structures, and Reactivities of {Fe−NO}6 Nitrosyls Derived from Polypyridine-Carboxamide Ligands: Photoactive NO-Donors and Reagents for S-Nitrosylation of Alkyl Thiols. Inorg Chem 2004; 43:5736-43. [PMID: 15332826 DOI: 10.1021/ic040057c] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two new iron nitrosyls derived from two designed pentadentate ligands N,N-bis(2-pyridylmethyl)-amine-N'-(2-pyridylmethyl)acetamide and N,N-bis(2-pyridylmethyl)-amine-N'-[1-(2-pyridinyl)ethyl]acetamide (PcPy(3)H and MePcPy(3)H, respectively, where H is the dissociable amide proton) have been structurally characterized. These complexes are similar to a previously reported (Fe-NO)6 complex, [(PaPy(3))Fe(NO)](ClO(4))(2) (1) that releases NO under mild conditions. The present nitrosyls, namely [(PcPy(3))Fe(NO)](ClO(4))(2) (2) and [(MePcPy(3))Fe(NO)](ClO(4))(2) (3), belong to the same (Fe-NO)6 family and exhibit (a) clean (1)H NMR spectra in CD(3)CN indicating S = 0 ground state, (b) almost linear Fe-N-O angles (177.3(5) degrees and 177.6(4) degrees for 2 and 3, respectively), and (c) N-O stretching frequencies (nu(NO)) in the range 1900-1925 cm(-)(1). The binding of NO at the non-heme iron centers of 1-3 is completely reversible and all three nitrosyls rapidly release NO when exposed to light (50 W tungsten bulb). In addition to acting as photoactive NO-donors, these complexes also nitrosylate thiols such as N-acetylpenicillamine, 3-mercaptopropionic acid, and N-acetyl-cysteine-methyl-ester in yields that range from 30 to 90% in the absence of light. The addition of alkyl or aryl thiolate (RS(-)) to the (Fe-NO)6 complexes in the absence of dioxygen results in the reduction of the iron metal center to afford the corresponding (Fe-NO)7 species.
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Affiliation(s)
- Raman K Afshar
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
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Harrop TC, Mascharak PK. Fe(III) and Co(III) centers with carboxamido nitrogen and modified sulfur coordination: lessons learned from nitrile hydratase. Acc Chem Res 2004; 37:253-60. [PMID: 15096062 DOI: 10.1021/ar0301532] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitrile hydratase (NHase) is a non-heme Fe(III) or non-corrinoid Co(III) metalloenzyme with an unprecedented coordination sphere comprising deprotonated carboxamido nitrogens and modified Cys-S (-SO(-) and -SO(2)(-)) sulfurs. We have synthesized model complexes derived from designed ligands that contain these donor groups. The model complexes mimic almost all the intrinsic properties of the unique M(III) (M = Fe, Co) active site of NHase. Even a functional Co(III) model has been synthesized that hydrolyzes nitriles catalytically at pH close to the optimum pH of the enzyme. Our studies have provided insight into how the unusual donor atoms dictate the overall properties of the biological M(III) sites.
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Affiliation(s)
- Todd C Harrop
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
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Rotthaus O, LeRoy S, Tomas A, Barkigia K, Artaud I. A New Family of Low-Spin CoIII Bis(amidate) Complexes with Twocis ortrans Cyanides. Eur J Inorg Chem 2004. [DOI: 10.1002/ejic.200300645] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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38
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Patra AK, Rowland JM, Marlin DS, Bill E, Olmstead MM, Mascharak PK. Iron nitrosyls of a pentadentate ligand containing a single carboxamide group: syntheses, structures, electronic properties, and photolability of NO. Inorg Chem 2004; 42:6812-23. [PMID: 14552634 DOI: 10.1021/ic0301627] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Three iron complexes of a pentadentate ligand N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-carboxamide (PaPy(3)H, H is the dissociable amide proton) have been synthesized. All three species, namely, two nitrosyls [(PaPy(3))Fe(NO)](ClO(4))(2) (2) and [(PaPy(3))Fe(NO)](ClO(4)) (3) and one nitro complex [(PaPy(3))Fe(NO(2))](ClO(4)) (4), have been structurally characterized. These complexes provide the opportunity to compare the structural and spectral properties of a set of isostructural [Fe-NO](6,7) complexes (2 and 3, respectively) and an analogous genuine Fe(III) complex with an "innocent" sixth ligand ([(PaPy(3))Fe(NO(2))](ClO(4)), 4). The most striking difference in the structural features of 2 and 3 is the Fe-N-O angle (Fe-N-O = 173.1(2) degrees in the case of 2 and 141.29(15) degrees in the case of 3). The clean (1)H NMR spectrum of 2 in CD(3)CN reveals its S = 0 ground state and confirms its [Fe-NO](6) configuration. The binding of NO at the non-heme iron center in 2 is completely reversible and the bound NO is photolabile. Mössbauer data, electron paramagnetic resonance signal at g approximately 2.00, and variable temperature magnetic susceptibility measurements indicate the S = (1)/(2) spin state of the [Fe-NO](7) complex 3. Analysis of the spectroscopic data suggests Fe(II)-NO(+) and Fe(II)-NO(*) formulations for 2 and 3, respectively. The bound NO in 3 does not show any photolability. However, in MeCN solution, it reacts rapidly with dioxygen to afford the nitro complex 4, which has also been synthesized independently from [(PaPy(3))Fe(MeCN)](2+) and NO(2)(-). Nucleophilic attack of hydroxide ion to the N atom of the NO ligand in 2 in MeCN in the dark gives rise to 4 in high yield.
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Affiliation(s)
- Apurba K Patra
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
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