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Hubbard CD, Chatterjee D, Oszajca M, Polaczek J, Impert O, Chrzanowska M, Katafias A, Puchta R, van Eldik R. Inorganic reaction mechanisms. A personal journey. Dalton Trans 2020; 49:4599-4659. [PMID: 32162632 DOI: 10.1039/c9dt04620h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This review covers highlights of the work performed in the van Eldik group on inorganic reaction mechanisms over the past two decades in the form of a personal journey. Topics that are covered include, from NO to HNO chemistry, peroxide activation in model porphyrin and enzymatic systems, the wonder-world of RuIII(edta) chemistry, redox chemistry of Ru(iii) complexes, Ru(ii) polypyridyl complexes and their application, relevant physicochemical properties and reaction mechanisms in ionic liquids, and mechanistic insight from computational chemistry. In each of these sections, typical examples of mechanistic studies are presented in reference to related work reported in the literature.
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Affiliation(s)
- Colin D Hubbard
- Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Egerlandstr. 1, 91058 Erlangen, Germany.
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Mechanistic Studies on the Reaction of [Fe
III
(edta)(H
2
O)]
–
with Piloty′s Acid as Source for HNO. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201900261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Dees A, Jux N, Tröppner O, Dürr K, Lippert R, Schmid M, Küstner B, Schlücker S, Steinrück HP, Gottfried JM, Ivanović-Burmazović I. Reactions of Superoxide with Iron Porphyrins in the Bulk and the Near-Surface Region of Ionic Liquids. Inorg Chem 2015; 54:6862-72. [PMID: 26158848 DOI: 10.1021/acs.inorgchem.5b00770] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The redox reaction of superoxide (KO2) with highly charged iron porphyrins (Fe(P4+), Fe(P8+), and Fe(P8-)) has been investigated in the ionic liquids (IL) [EMIM][Tf2N] (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and [EMIM][B(CN)4] (1-ethyl-3-methylimidazolium tetracyanoborate) by using time-resolved UV/vis stopped-flow, electrochemistry, cryospray mass spectrometry, EPR, and XPS measurements. Stable KO2 solutions in [EMIM][Tf2N] can be prepared up to a 15 mM concentration and are characterized by a signal in EPR spectrum at g = 2.0039 and by the 1215 cm(-1) stretching vibration in the resonance Raman spectrum. While the negatively charged iron porphyrin Fe(P8-) does not react with superoxide in IL, Fe(P4+) and Fe(P8+) do react in a two-step process (first a reduction of the Fe(III) to the Fe(II) form, followed by the binding of superoxide to Fe(II)). In the reaction with KO2, Fe(P4+) and Fe(P8+) show similar rate constants (e.g., in the case of Fe(P4+): k1 = 18.6 ± 0.5 M(-1) s(-1) for the first reaction step, and k2 = 2.8 ± 0.1 M(-1) s(-1) for the second reaction step). Notably, these rate constants are four to five orders of magnitude lower in [EMIM][Tf2N] than in conventional solvents such as DMSO. The influence of the ionic liquid is also apparent during electrochemical experiments, where the redox potentials for the corresponding Fe(III)/Fe(II) couples are much more negative in [EMIM][Tf2N] than in DMSO. This modified redox and kinetic behavior of the positively charged iron porphyrins results from their interactions with the anions of the ionic liquid, while the nucleophilicity of the superoxide is reduced by its interactions with the cations of the ionic liquid. A negligible vapor pressure of [EMIM][B(CN)4] and a sufficient enrichment of Fe(P8+) in a close proximity to the surface enabled XPS measurements as a case study for monitoring direct changes in the electronic structure of the metal centers during redox processes in solution and at liquid/solid interfaces.
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Affiliation(s)
- Anne Dees
- †Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Norbert Jux
- †Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Oliver Tröppner
- †Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Katharina Dürr
- †Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Rainer Lippert
- †Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Martin Schmid
- ‡Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | - Bernd Küstner
- §Institute for Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Sebastian Schlücker
- §Institute for Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Hans-Peter Steinrück
- †Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - J Michael Gottfried
- †Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,‡Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | - Ivana Ivanović-Burmazović
- †Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Arcon JP, Rosi P, Petruk AA, Marti MA, Estrin DA. Molecular Mechanism of Myoglobin Autoxidation: Insights from Computer Simulations. J Phys Chem B 2015; 119:1802-13. [DOI: 10.1021/jp5093948] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. P. Arcon
- Departamento
de Química Inorgánica, Analítica y Química
Física e INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA, Ciudad de Buenos Aires, Argentina
- Departamento
de Química Biológica, Facultad de Ciencias Exactas y
Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón
2, C1428EHA, Ciudad
de Buenos Aires, Argentina
| | - P. Rosi
- Departamento
de Química Inorgánica, Analítica y Química
Física e INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA, Ciudad de Buenos Aires, Argentina
| | - A. A. Petruk
- Departamento
de Química Inorgánica, Analítica y Química
Física e INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA, Ciudad de Buenos Aires, Argentina
| | - M. A. Marti
- Departamento
de Química Inorgánica, Analítica y Química
Física e INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA, Ciudad de Buenos Aires, Argentina
- Departamento
de Química Biológica, Facultad de Ciencias Exactas y
Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón
2, C1428EHA, Ciudad
de Buenos Aires, Argentina
| | - D. A. Estrin
- Departamento
de Química Inorgánica, Analítica y Química
Física e INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA, Ciudad de Buenos Aires, Argentina
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Affiliation(s)
- Luisa B. Maia
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - José J. G. Moura
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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Wyer JA, Jørgensen AV, Møller Pedersen B, Brøndsted Nielsen S. Gas-phase spectroscopy of ferric heme-NO complexes. Chemphyschem 2013; 14:4109-13. [PMID: 24166979 DOI: 10.1002/cphc.201300843] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Indexed: 11/10/2022]
Abstract
Weakly bound complexes between ferric heme cations and NO were synthesised in the gas phase from ion-molecule reactions, and their absorption measured based on photodissociation yields. The Soret band, which serves as an important marker band for heme-protein spectroscopy, is maximal at 357±5 nm and significantly blue-shifted compared to ferric heme nitrosyl proteins (maxima between 408 and 422 nm). This is in stark contrast to the Q-band absorption where the protein microenvironment is nearly innocent in perturbing the electronic structure of the porphyrin macrocycle. Photodissociation is primarily through loss of NO. In contrast to the Q-band region, two-photon absorption was seen in the Soret band despite NO loss only requiring ∼1 eV. A model based on intersystem crossing to a long-lived triplet state where a barrier has to be surmounted is suggested. Finally, we summarise the measured absorption maxima of heme and its complexes with amino acids and NO.
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Affiliation(s)
- Jean A Wyer
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C (Denmark), Fax: (+45) 8612 0740.
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Miljkovic JL, Kenkel I, Ivanović-Burmazović I, Filipovic MR. Generation of HNO and HSNO from Nitrite by Heme-Iron-Catalyzed Metabolism with H2S. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201305669] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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Miljkovic JL, Kenkel I, Ivanović-Burmazović I, Filipovic MR. Generation of HNO and HSNO from Nitrite by Heme-Iron-Catalyzed Metabolism with H2S. Angew Chem Int Ed Engl 2013; 52:12061-4. [DOI: 10.1002/anie.201305669] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Indexed: 01/30/2023]
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Franke A, van Eldik R. Factors That Determine the Mechanism of NO Activation by Metal Complexes of Biological and Environmental Relevance. Eur J Inorg Chem 2012. [DOI: 10.1002/ejic.201201111] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Wyer JA, Brøndsted Nielsen S. Absorption by Isolated Ferric Heme Nitrosyl Cations In Vacuo. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201206213] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Wyer JA, Brøndsted Nielsen S. Absorption by Isolated Ferric Heme Nitrosyl Cations In Vacuo. Angew Chem Int Ed Engl 2012; 51:10256-60. [DOI: 10.1002/anie.201206213] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Indexed: 11/12/2022]
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Hopmann KH, Cardey B, Gladwin MT, Kim-Shapiro DB, Ghosh A. Hemoglobin as a nitrite anhydrase: modeling methemoglobin-mediated N2O3 formation. Chemistry 2011; 17:6348-58. [PMID: 21590821 DOI: 10.1002/chem.201003578] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Indexed: 11/07/2022]
Abstract
Nitrite has recently been recognized as a storage form of NO in blood and as playing a key role in hypoxic vasodilation. The nitrite ion is readily reduced to NO by hemoglobin in red blood cells, which, as it happens, also presents a conundrum. Given NO's enormous affinity for ferrous heme, a key question concerns how it escapes capture by hemoglobin as it diffuses out of the red cells and to the endothelium, where vasodilation takes place. Dinitrogen trioxide (N(2)O(3)) has been proposed as a vehicle that transports NO to the endothelium, where it dissociates to NO and NO(2). Although N(2)O(3) formation might be readily explained by the reaction Hb-Fe(3+)+NO(2)(-)+NO⇌Hb-Fe(2+)+N(2)O(3), the exact manner in which methemoglobin (Hb-Fe(3+)), nitrite and NO interact with one another is unclear. Both an "Hb-Fe(3+)-NO(2)(-)+NO" pathway and an "Hb-Fe(3+)-NO+NO(2)(-) " pathway have been proposed. Neither pathway has been established experimentally. Nor has there been any attempt until now to theoretically model N(2)O(3) formation, the so-called nitrite anhydrase reaction. Both pathways have been examined here in a detailed density functional theory (DFT, B3LYP/TZP) study and both have been found to be feasible based on energetics criteria. Modeling the "Hb-Fe(3+)-NO(2)(-)+NO" pathway proved complex. Not only are multiple linkage-isomeric (N- and O-coordinated) structures conceivable for methemoglobin-nitrite, multiple isomeric forms are also possible for N(2)O(3) (the lowest-energy state has an N-N-bonded nitronitrosyl structure, O(2)N-NO). We considered multiple spin states of methemoglobin-nitrite as well as ferromagnetic and antiferromagnetic coupling of the Fe(3+) and NO spins. Together, the isomerism and spin variables result in a diabolically complex combinatorial space of reaction pathways. Fortunately, transition states could be successfully calculated for the vast majority of these reaction channels, both M(S)=0 and M(S)=1. For a six-coordinate Fe(3+)-O-nitrito starting geometry, which is plausible for methemoglobin-nitrite, we found that N(2)O(3) formation entails barriers of about 17-20 kcal mol(-1) , which is reasonable for a physiologically relevant reaction. For the "Hb-Fe(3+) -NO+NO(2) (-) " pathway, which was also found to be energetically reasonable, our calculations indicate a two-step mechanism. The first step involves transfer of an electron from NO(2)(-) to the Fe(3+)-heme-NO center ({FeNO}(6)) , resulting in formation of nitrogen dioxide and an Fe(2+)-heme-NO center ({FeNO}(7)). Subsequent formation of N(2)O(3) entails a barrier of only 8.1 kcal mol(-1) . From an energetics point of view, the nitrite anhydrase reaction thus is a reasonable proposition. Although it is tempting to interpret our results as favoring the "{FeNO}(6)+NO(2)(-) " pathway over the "Fe(3+)-nitrite+NO" pathway, both pathways should be considered energetically reasonable for a biological reaction and it seems inadvisable to favor a unique reaction channel based solely on quantum chemical modeling.
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Affiliation(s)
- Kathrin H Hopmann
- Centre for Theoretical and Computational Chemistry and Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway
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Lanucara F, Chiavarino B, Crestoni ME, Scuderi D, Sinha RK, Maı̂tre P, Fornarini S. Naked Five-Coordinate FeIII(NO) Porphyrin Complexes: Vibrational and Reactivity Features. Inorg Chem 2011; 50:4445-52. [DOI: 10.1021/ic200073v] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Francesco Lanucara
- Dipartimento di Chimica e Tecnologie del Farmaco, Università di Roma “La Sapienza”, P.le A. Moro 5, I-00185, Roma, Italy
| | - Barbara Chiavarino
- Dipartimento di Chimica e Tecnologie del Farmaco, Università di Roma “La Sapienza”, P.le A. Moro 5, I-00185, Roma, Italy
| | - Maria Elisa Crestoni
- Dipartimento di Chimica e Tecnologie del Farmaco, Università di Roma “La Sapienza”, P.le A. Moro 5, I-00185, Roma, Italy
| | - Debora Scuderi
- Laboratoire de Chimie Physique, UMR8000 CNRS, Faculté des Sciences, Université Paris Sud, Bâtiment 350, 91405 Orsay Cedex, France
| | - Rajeev K. Sinha
- Laboratoire de Chimie Physique, UMR8000 CNRS, Faculté des Sciences, Université Paris Sud, Bâtiment 350, 91405 Orsay Cedex, France
| | - Philippe Maı̂tre
- Laboratoire de Chimie Physique, UMR8000 CNRS, Faculté des Sciences, Université Paris Sud, Bâtiment 350, 91405 Orsay Cedex, France
| | - Simonetta Fornarini
- Dipartimento di Chimica e Tecnologie del Farmaco, Università di Roma “La Sapienza”, P.le A. Moro 5, I-00185, Roma, Italy
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Stasicka Z. Transition metal complexes as solar photocatalysts in the environment. ADVANCES IN INORGANIC CHEMISTRY 2011. [DOI: 10.1016/b978-0-12-385904-4.00004-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Affiliation(s)
- Peter C. Ford
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93110-9510
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Ostera G, Tokumasu F, Teixeira C, Collin N, Sa J, Hume J, Kumar S, Ribeiro J, Lukat-Rodgers GS, Rodgers KR. Plasmodium falciparum: nitric oxide modulates heme speciation in isolated food vacuoles. Exp Parasitol 2010; 127:1-8. [PMID: 20493843 DOI: 10.1016/j.exppara.2010.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 03/25/2010] [Accepted: 05/15/2010] [Indexed: 01/18/2023]
Abstract
Nitric oxide (NO) and NO-derived reactive nitrogen species (RNS) are present in the food vacuole (FV) of Plasmodium falciparum trophozoites. The product of PFL1555w, a putative cytochrome b(5), localizes in the FV membrane, similar to what was previously observed for the product of PF13_0353, a putative cytochrome b(5) reductase. These two gene products may contribute to NO generation by denitrification chemistry from nitrate and/or nitrite present in the erythrocyte cytosol. The possible coordination of NO to heme species present in the food vacuole was probed by resonance Raman spectroscopy. The spectroscopic data revealed that in situ generated NO interacts with heme inside the intact FVs to form ferrous heme nitrosyl complexes that influence intra-vacuolar heme solubility. The formation of heme nitrosyl complexes within the FV is a previously unrecognized factor that could affect the equilibrium between soluble and crystallized heme within the FV in vivo.
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Affiliation(s)
- Graciela Ostera
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
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Heinecke J, Ford PC. Mechanistic studies of nitrite reactions with metalloproteins and models relevant to mammalian physiology. Coord Chem Rev 2010. [DOI: 10.1016/j.ccr.2009.07.021] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Schmeisser M, van Eldik R. Thermodynamic and Kinetic Studies on Reactions of FeIII(meso-[tetra(3-sulfonatomesityl)porphin]) with NO in an Ionic Liquid. Trace Impurities Can Change the Mechanism! Inorg Chem 2009; 48:7466-75. [DOI: 10.1021/ic9006247] [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)
- Matthias Schmeisser
- Inorganic Chemistry, Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Rudi van Eldik
- Inorganic Chemistry, Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
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Olabe JA. The coordination chemistry of nitrosyl in cyanoferrates. An exhibit of bioinorganic relevant reactions. Dalton Trans 2008:3633-48. [DOI: 10.1039/b803153c] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Roncaroli F, Videla M, Slep LD, Olabe JA. New features in the redox coordination chemistry of metal nitrosyls {M–NO+; M–NO; M–NO−(HNO)}. Coord Chem Rev 2007. [DOI: 10.1016/j.ccr.2007.04.012] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Jee JE, Eigler S, Jux N, Zahl A, van Eldik R. Influence of an Extremely Negatively Charged Porphyrin on the Reversible Binding Kinetics of NO to Fe(III) and the Subsequent Reductive Nitrosylation. Inorg Chem 2007; 46:3336-52. [PMID: 17375907 DOI: 10.1021/ic061732g] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The polyanionic, water-soluble, and non-micro-oxo dimer-forming iron porphyrin (hexadecasodium iron 54,104,154,204-tetra-t-butyl-52,56,102,106,152,156,202,206-octakis[2,2-bis(carboxylato)ethyl]-5,10,15,20-tetraphenylporphyrin), (P16-)FeIII, with 16 negatively charged meso substituents on the porphyrin was synthesized and fully characterized by UV-vis and 1H NMR spectroscopy. A single pKa1 value of 9.90 +/- 0.01 was determined for the deprotonation of coordinated water in the six-coordinate (P16-)FeIII(H2O)2 and as attributed to the formation of the five-coordinate monohydroxo-ligated form, (P16-)FeIII(OH). The porphyrin complex reversibly binds NO in aqueous solution to yield the nitric oxide adduct, (P16-)FeII(NO+)(L), where L = H2O or OH-. The kinetics for the reversible binding of NO were studied as a function of pH, temperature, and pressure using the stopped-flow technique. The data for the binding of NO to the diaqua complex are consistent with the operation of a dissociative mechanism on the basis of the significantly positive values of DeltaS and DeltaV, whereas the monohydroxo complex favors an associatively activated mechanism as determined from the corresponding negative activation parameters. The rate constant, kon = 3.1 x 104 M-1 s-1 at 25 degrees C, determined for the NO binding to (P16-)FeIII(OH) at higher pH, is significantly lower than the corresponding value measured for (P16-)FeIII(H2O)2 at lower pH, namely, kon = 11.3 x 105 M-1 s-1 at 25 degrees C. This decrease in the reactivity is analogous to that reported for other diaqua- and monohydroxo-ligated ferric porphyrin complexes, and is accounted for in terms of a mechanistic changeover observed for (P16-)FeIII(H2O)2 and (P16-)FeIII(OH). The formed nitrosyl complex, (P16-)FeII(NO+)(H2O), undergoes subsequent reductive nitrosylation to produce (P16-)FeII(NO), which is catalyzed by nitrite produced during the reaction. Concentration-, pH-, temperature-, and pressure-dependent kinetic data are reported for this reaction. Data for the reversible binding of NO and the subsequent reductive nitrosylation reaction are discussed in reference to that available for other iron(III) porphyrins in terms of the influence of the porphyrin periphery.
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Affiliation(s)
- Joo-Eun Jee
- Institute for Inorganic Chemistry, University of Erlangen-Nürnberg, Erlangen, Germany
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Franke A, Roncaroli F, van Eldik R. Mechanistic Studies on the Activation of NO by Iron and Cobalt Complexes. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200600921] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Alicja Franke
- Institute for Inorganic Chemistry, University of Erlangen‐Nürnberg, Egerlandstr. 1, 91058 Erlangen, Germany
| | - Federico Roncaroli
- Institute for Inorganic Chemistry, University of Erlangen‐Nürnberg, Egerlandstr. 1, 91058 Erlangen, Germany
- Department of Inorganic, Analytical and Physical Chemistry, INQUIMAE, Faculty of Exact and Natural Sciences, University of Buenos Aires, C1428EHA Buenos Aires, Argentina
| | - Rudi van Eldik
- Institute for Inorganic Chemistry, University of Erlangen‐Nürnberg, Egerlandstr. 1, 91058 Erlangen, Germany
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