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http://hdl.handle.net/1843/50329| Tipo: | Artigo de Periódico |
| Título: | NO/H2S “crosstalk” reactions. The role of thionitrites (SNO−) and perthionitrites (SSNO−) |
| Autor(es): | Juan Pablo Marcolongo Mateus Fernandes Venâncio Willian Ricardo Rocha Fabio Doctorovich José Antonio Olabe |
| Resumen: | The redox chemistry of H2S with NO and other oxidants containing the NO group is discussed on a mechanistic basis because of the expanding interest in their biological relevance, with an eye open to the chemical differences of H2S and thiols RSH. We focus on the properties of two “crosstalk” intermediates, SNO– (thionitrite) and SSNO– (perthionitrite, nitrosodisulfide) based in the largely controversial status on their identity and chemistry in aqueous/nonaqueous media, en route to the final products N2O, NO2–, NH2OH/NH3, and S8. Thionitrous acid, generated either in the direct reaction of NO + H2S or through the transnitrosation of RSNO’s (nitrosothiols) with H2S at pH 7.4, is best described as a mixture of rapidly interconverting isomers, {(H)SNO}. It is reactive in different competitive modes, with a half-life of a few seconds at pH 7.4 for homolytic cleavage of the N–S bond, and could be deprotonated at pH values of up to ca. 10, giving SNO–, a less reactive species than {(H)SNO}. The latter mixture can also react with HS–, giving HNO and HS2– (hydrogen disulfide), a S0(sulfane)-transfer reagent toward {(H)SNO}, leading to SSNO–, a moderately stable species that slowly decomposes in aqueous sulfide-containing solutions in the minute–hour time scale, depending on [O2]. The previous characterization of HSNO/SNO– and SSNO– is critically discussed based on the available chemical and spectroscopic evidence (mass spectrometry, UV–vis, 15N NMR, Fourier transform infrared), together with computational studies including quantum mechanics/molecular mechanics molecular dynamics simulations that provide a structural and UV–vis description of the solvatochromic properties of cis-SSNO– acting as an electron donor in water, alcohols, and aprotic acceptor solvents. In this way, SSNO– is confirmed as the elusive “yellow intermediate” (I412) emerging in the aqueous crosstalk reactions, in contrast with its assignment to polysulfides, HSn–. The analysis extends to the coordination abilities of {(H)SNO}, SNO–, and SSNO– into heme and nonheme iron centers, providing a basis for best unraveling their putative specific signaling roles. |
| Asunto: | Físico-química Química inorgânica Cinética química Estrutura molecular Solução (Química) Absorção Solventes Mecânica quântica Funcionais de densidade Análise espectral Espectrometria de massa Fourier, Espectroscopia de infravermelho por transformada de Espectroscopia de ressonância nuclear Espectroscopia visível Espectroscopia de ultravioleta |
| Idioma: | eng |
| País: | Brasil |
| Editor: | Universidade Federal de Minas Gerais |
| Sigla da Institución: | UFMG |
| Departamento: | ICX - DEPARTAMENTO DE QUÍMICA |
| Tipo de acceso: | Acesso Restrito |
| Identificador DOI: | https://doi.org/10.1021/acs.inorgchem.9b01978 |
| URI: | http://hdl.handle.net/1843/50329 |
| Fecha del documento: | 2019 |
| metadata.dc.url.externa: | https://pubs.acs.org/doi/10.1021/acs.inorgchem.9b01978 |
| Aparece en las colecciones: | Artigo de Periódico |
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