Reactivity of iron(II)-bound nitrosyl hydride (HNO, nitroxyl) in aqueous solution

The reactivity of coordinated nitroxyl (HNO) has been explored with the [FeII(CN)5HNO]3 - complex in aqueous medium, pH 6. We discuss essential biorelevant issues as the thermal and photochemical decompositions, the reactivity toward HNO dissociation, the electrochemical behavior, and the reactions...

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Publicado:	2013
Materias:	Nitrosyl hydride Nitroxyl Pentacyanoferrate dithionite ferricyanide ferrous ion iron nitrogen nitrogen derivative nitroprusside sodium nitrosyl hydride paraquat unclassified drug aqueous solution article chemical bond chemical reaction controlled study decomposition dissociation electrochemistry electron transport nitrosylation oxidation pH photochemistry synthesis thermodynamics Coordination Complexes Dithionite Electrochemistry Ferricyanides Ferrous Compounds Kinetics Nitrogen Oxides Nitroprusside Oxidants Oxidation-Reduction Paraquat Photochemical Processes Reducing Agents Solutions Spectrophotometry, Ultraviolet Kobus
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01620134_v118_n_p108_Montenegro http://hdl.handle.net/20.500.12110/paper_01620134_v118_n_p108_Montenegro
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

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spelling	paper:paper_01620134_v118_n_p108_Montenegro2023-06-08T15:13:35Z Reactivity of iron(II)-bound nitrosyl hydride (HNO, nitroxyl) in aqueous solution Nitrosyl hydride Nitroxyl Pentacyanoferrate dithionite ferricyanide ferrous ion iron nitrogen nitrogen derivative nitroprusside sodium nitrosyl hydride paraquat unclassified drug aqueous solution article chemical bond chemical reaction controlled study decomposition dissociation electrochemistry electron transport nitrosylation oxidation pH photochemistry synthesis thermodynamics Coordination Complexes Dithionite Electrochemistry Ferricyanides Ferrous Compounds Kinetics Nitrogen Oxides Nitroprusside Oxidants Oxidation-Reduction Paraquat Photochemical Processes Reducing Agents Solutions Spectrophotometry, Ultraviolet Kobus The reactivity of coordinated nitroxyl (HNO) has been explored with the [FeII(CN)5HNO]3 - complex in aqueous medium, pH 6. We discuss essential biorelevant issues as the thermal and photochemical decompositions, the reactivity toward HNO dissociation, the electrochemical behavior, and the reactions with oxidizing and reducing agents. The spontaneous decomposition in the absence of light yielded a two-electron oxidized species, the nitroprusside anion, [FeII(CN)5NO]2-, and a negligible quantity of N2O, with kobs ≈ 5 × 10- 7 s- 1, at 25.0 °C. The value of kobs represents an upper limit for HNO release, comparable to values reported for other structurally related L ligands in the [FeII(CN) 5L]n- series. These results reveal that the FeN bond is strong, suggesting a significant σ-π interaction, as already postulated for other HNO-complexes. The [FeII(CN)5HNO]3- ion showed a quasi-reversible oxidation wave at 0.32 V (vs normal hydrogen electrode), corresponding to the [FeII(CN)5HNO] 3-/[FeII(CN)5NO]3-,H+ redox couple. Hexacyanoferrate(III), methylviologen and the nitroprusside ion have been selected as potential oxidants. Only the first reactant achieved a complete oxidation process, initiated by a proton-coupled electron transfer reaction at the HNO ligand, with nitroprusside as a final oxidation product. Dithionite acted as a reductant of [FeII(CN)5HNO] 3-, in a 4-electron process, giving NH3. The high stability of bound HNO may resemble the properties in related Fe(II) centers of redox active enzymes. The very minor release of N2O shows that the redox conversions may evolve without disruption of the FeN bonds, under competitive conditions with the dissociation of HNO. © 2012 Elsevier Inc. All rights reserved. 2013 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01620134_v118_n_p108_Montenegro http://hdl.handle.net/20.500.12110/paper_01620134_v118_n_p108_Montenegro
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Nitrosyl hydride Nitroxyl Pentacyanoferrate dithionite ferricyanide ferrous ion iron nitrogen nitrogen derivative nitroprusside sodium nitrosyl hydride paraquat unclassified drug aqueous solution article chemical bond chemical reaction controlled study decomposition dissociation electrochemistry electron transport nitrosylation oxidation pH photochemistry synthesis thermodynamics Coordination Complexes Dithionite Electrochemistry Ferricyanides Ferrous Compounds Kinetics Nitrogen Oxides Nitroprusside Oxidants Oxidation-Reduction Paraquat Photochemical Processes Reducing Agents Solutions Spectrophotometry, Ultraviolet Kobus
spellingShingle	Nitrosyl hydride Nitroxyl Pentacyanoferrate dithionite ferricyanide ferrous ion iron nitrogen nitrogen derivative nitroprusside sodium nitrosyl hydride paraquat unclassified drug aqueous solution article chemical bond chemical reaction controlled study decomposition dissociation electrochemistry electron transport nitrosylation oxidation pH photochemistry synthesis thermodynamics Coordination Complexes Dithionite Electrochemistry Ferricyanides Ferrous Compounds Kinetics Nitrogen Oxides Nitroprusside Oxidants Oxidation-Reduction Paraquat Photochemical Processes Reducing Agents Solutions Spectrophotometry, Ultraviolet Kobus Reactivity of iron(II)-bound nitrosyl hydride (HNO, nitroxyl) in aqueous solution
topic_facet	Nitrosyl hydride Nitroxyl Pentacyanoferrate dithionite ferricyanide ferrous ion iron nitrogen nitrogen derivative nitroprusside sodium nitrosyl hydride paraquat unclassified drug aqueous solution article chemical bond chemical reaction controlled study decomposition dissociation electrochemistry electron transport nitrosylation oxidation pH photochemistry synthesis thermodynamics Coordination Complexes Dithionite Electrochemistry Ferricyanides Ferrous Compounds Kinetics Nitrogen Oxides Nitroprusside Oxidants Oxidation-Reduction Paraquat Photochemical Processes Reducing Agents Solutions Spectrophotometry, Ultraviolet Kobus
description	The reactivity of coordinated nitroxyl (HNO) has been explored with the [FeII(CN)5HNO]3 - complex in aqueous medium, pH 6. We discuss essential biorelevant issues as the thermal and photochemical decompositions, the reactivity toward HNO dissociation, the electrochemical behavior, and the reactions with oxidizing and reducing agents. The spontaneous decomposition in the absence of light yielded a two-electron oxidized species, the nitroprusside anion, [FeII(CN)5NO]2-, and a negligible quantity of N2O, with kobs ≈ 5 × 10- 7 s- 1, at 25.0 °C. The value of kobs represents an upper limit for HNO release, comparable to values reported for other structurally related L ligands in the [FeII(CN) 5L]n- series. These results reveal that the FeN bond is strong, suggesting a significant σ-π interaction, as already postulated for other HNO-complexes. The [FeII(CN)5HNO]3- ion showed a quasi-reversible oxidation wave at 0.32 V (vs normal hydrogen electrode), corresponding to the [FeII(CN)5HNO] 3-/[FeII(CN)5NO]3-,H+ redox couple. Hexacyanoferrate(III), methylviologen and the nitroprusside ion have been selected as potential oxidants. Only the first reactant achieved a complete oxidation process, initiated by a proton-coupled electron transfer reaction at the HNO ligand, with nitroprusside as a final oxidation product. Dithionite acted as a reductant of [FeII(CN)5HNO] 3-, in a 4-electron process, giving NH3. The high stability of bound HNO may resemble the properties in related Fe(II) centers of redox active enzymes. The very minor release of N2O shows that the redox conversions may evolve without disruption of the FeN bonds, under competitive conditions with the dissociation of HNO. © 2012 Elsevier Inc. All rights reserved.
title	Reactivity of iron(II)-bound nitrosyl hydride (HNO, nitroxyl) in aqueous solution
title_short	Reactivity of iron(II)-bound nitrosyl hydride (HNO, nitroxyl) in aqueous solution
title_full	Reactivity of iron(II)-bound nitrosyl hydride (HNO, nitroxyl) in aqueous solution
title_fullStr	Reactivity of iron(II)-bound nitrosyl hydride (HNO, nitroxyl) in aqueous solution
title_full_unstemmed	Reactivity of iron(II)-bound nitrosyl hydride (HNO, nitroxyl) in aqueous solution
title_sort	reactivity of iron(ii)-bound nitrosyl hydride (hno, nitroxyl) in aqueous solution
publishDate	2013
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01620134_v118_n_p108_Montenegro http://hdl.handle.net/20.500.12110/paper_01620134_v118_n_p108_Montenegro
_version_	1768542783344214016

Reactivity of iron(II)-bound nitrosyl hydride (HNO, nitroxyl) in aqueous solution

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