Catalytic oxidation of hydroxyurea to bound NO+/ NO2 - Mediated by pentacyano(L)ferrates. Characterization of the nitroxide radical, bound C-nitrosoformamide and NO• as reaction intermediates
Hydroxyurea (HU, NH2CONHOH), reacts with several oxidizing agents (O2, H2O2, IO4-, Fe(III) complexes) in aqueous solutions containing either of the pentacyano(aqua)ferrate(II,III) ions, [FeII,III(CN)5H 2O]3,2-. In the initial 1-electron step, HU reacts with [FeIII(CN)5H2O]2- through an outer-sphere...
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2011
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201693_v374_n1_p447_Montenegro http://hdl.handle.net/20.500.12110/paper_00201693_v374_n1_p447_Montenegro |
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paper:paper_00201693_v374_n1_p447_Montenegro2023-06-08T14:40:54Z Catalytic oxidation of hydroxyurea to bound NO+/ NO2 - Mediated by pentacyano(L)ferrates. Characterization of the nitroxide radical, bound C-nitrosoformamide and NO• as reaction intermediates Montenegro, Andrea Constanza Bari, Sara Elizabeth Olabe Iparraguirre, Jose Antonio C-nitrosoformamide Hydroxyurea Nitroxide Nitroxyl Pentacyano(L)ferrates Hydroxyurea (HU, NH2CONHOH), reacts with several oxidizing agents (O2, H2O2, IO4-, Fe(III) complexes) in aqueous solutions containing either of the pentacyano(aqua)ferrate(II,III) ions, [FeII,III(CN)5H 2O]3,2-. In the initial 1-electron step, HU reacts with [FeIII(CN)5H2O]2- through an outer-sphere process, leading to [FeII(CN)5H 2O]3- and the EPR active nitroxide radical, NH 2C(O)NHȮ. This is further oxidized to C-nitrosoformamide, NH2C(O)NO, in a similar 1-electron step. The latter compound binds to [FeII(CN)5H2O] 3- giving the [FeII(CN)5(NOC(O)NH 2)]3- ion (I3-). I3- has been isolated as a solid, Na3[FeII(CN)5(NOC(O) NH2)]·2H2O, (I), and was identified by chemical analysis, IR and UV-Vis spectroscopies (λmax = 465 nm, = 4.0 ± 0.3 × 103 M-1 cm-1). I and I3- are very stable species in anaerobic media, as solids and in aqueous solutions with a pH close to 7. I3- decomposes in alkaline media through hydrolysis, giving CO2, NH3 and, presumably, the nitroxyl complex [FeII(CN)5NO]4-. The latter ion appears as a source of N2O, detected by mass spectrometry, and affords, in oxygenated media, two subsequent 1-electron processes, without the rupture of the NO bond, giving the radical intermediate [Fe II(CN)5NO•]3- (which was identified by UV-Vis and EPR), and finally the nitroprusside ion, [Fe(CN) 5NO]2-. At pHs > 10, the latter ion may convert to [FeII(CN)5NO2]4-, and leads to [FeII(CN)5H2O]3- through the release of nitrite. Thus, the aqua-ion might afford a new 4-electron oxidation process if HU and the external oxidant were in excess. © 2011 Elsevier B.V. All rights reserved. Fil:Montenegro, A.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Bari, S.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Olabe, J.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2011 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201693_v374_n1_p447_Montenegro http://hdl.handle.net/20.500.12110/paper_00201693_v374_n1_p447_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 |
C-nitrosoformamide Hydroxyurea Nitroxide Nitroxyl Pentacyano(L)ferrates |
| spellingShingle |
C-nitrosoformamide Hydroxyurea Nitroxide Nitroxyl Pentacyano(L)ferrates Montenegro, Andrea Constanza Bari, Sara Elizabeth Olabe Iparraguirre, Jose Antonio Catalytic oxidation of hydroxyurea to bound NO+/ NO2 - Mediated by pentacyano(L)ferrates. Characterization of the nitroxide radical, bound C-nitrosoformamide and NO• as reaction intermediates |
| topic_facet |
C-nitrosoformamide Hydroxyurea Nitroxide Nitroxyl Pentacyano(L)ferrates |
| description |
Hydroxyurea (HU, NH2CONHOH), reacts with several oxidizing agents (O2, H2O2, IO4-, Fe(III) complexes) in aqueous solutions containing either of the pentacyano(aqua)ferrate(II,III) ions, [FeII,III(CN)5H 2O]3,2-. In the initial 1-electron step, HU reacts with [FeIII(CN)5H2O]2- through an outer-sphere process, leading to [FeII(CN)5H 2O]3- and the EPR active nitroxide radical, NH 2C(O)NHȮ. This is further oxidized to C-nitrosoformamide, NH2C(O)NO, in a similar 1-electron step. The latter compound binds to [FeII(CN)5H2O] 3- giving the [FeII(CN)5(NOC(O)NH 2)]3- ion (I3-). I3- has been isolated as a solid, Na3[FeII(CN)5(NOC(O) NH2)]·2H2O, (I), and was identified by chemical analysis, IR and UV-Vis spectroscopies (λmax = 465 nm, = 4.0 ± 0.3 × 103 M-1 cm-1). I and I3- are very stable species in anaerobic media, as solids and in aqueous solutions with a pH close to 7. I3- decomposes in alkaline media through hydrolysis, giving CO2, NH3 and, presumably, the nitroxyl complex [FeII(CN)5NO]4-. The latter ion appears as a source of N2O, detected by mass spectrometry, and affords, in oxygenated media, two subsequent 1-electron processes, without the rupture of the NO bond, giving the radical intermediate [Fe II(CN)5NO•]3- (which was identified by UV-Vis and EPR), and finally the nitroprusside ion, [Fe(CN) 5NO]2-. At pHs > 10, the latter ion may convert to [FeII(CN)5NO2]4-, and leads to [FeII(CN)5H2O]3- through the release of nitrite. Thus, the aqua-ion might afford a new 4-electron oxidation process if HU and the external oxidant were in excess. © 2011 Elsevier B.V. All rights reserved. |
| author |
Montenegro, Andrea Constanza Bari, Sara Elizabeth Olabe Iparraguirre, Jose Antonio |
| author_facet |
Montenegro, Andrea Constanza Bari, Sara Elizabeth Olabe Iparraguirre, Jose Antonio |
| author_sort |
Montenegro, Andrea Constanza |
| title |
Catalytic oxidation of hydroxyurea to bound NO+/ NO2 - Mediated by pentacyano(L)ferrates. Characterization of the nitroxide radical, bound C-nitrosoformamide and NO• as reaction intermediates |
| title_short |
Catalytic oxidation of hydroxyurea to bound NO+/ NO2 - Mediated by pentacyano(L)ferrates. Characterization of the nitroxide radical, bound C-nitrosoformamide and NO• as reaction intermediates |
| title_full |
Catalytic oxidation of hydroxyurea to bound NO+/ NO2 - Mediated by pentacyano(L)ferrates. Characterization of the nitroxide radical, bound C-nitrosoformamide and NO• as reaction intermediates |
| title_fullStr |
Catalytic oxidation of hydroxyurea to bound NO+/ NO2 - Mediated by pentacyano(L)ferrates. Characterization of the nitroxide radical, bound C-nitrosoformamide and NO• as reaction intermediates |
| title_full_unstemmed |
Catalytic oxidation of hydroxyurea to bound NO+/ NO2 - Mediated by pentacyano(L)ferrates. Characterization of the nitroxide radical, bound C-nitrosoformamide and NO• as reaction intermediates |
| title_sort |
catalytic oxidation of hydroxyurea to bound no+/ no2 - mediated by pentacyano(l)ferrates. characterization of the nitroxide radical, bound c-nitrosoformamide and no• as reaction intermediates |
| publishDate |
2011 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201693_v374_n1_p447_Montenegro http://hdl.handle.net/20.500.12110/paper_00201693_v374_n1_p447_Montenegro |
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1768544851785154560 |