| Autor: |
Mazumdar, Rakesh, Saha, Shankhadeep, Samanta, Bapan, Ghosh, Riya, Maity, Sayani, Mondal, Biplab |
| Předmět: |
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| Zdroj: |
Dalton Transactions: An International Journal of Inorganic Chemistry; 6/21/2023, Vol. 52 Issue 23, p7917-7925, 9p |
| Abstrakt: |
A five-coordinated {Mn(NO)}6 complex of Mn(II)–porphyrinate, [Mn(TMPP2−)(NO)], 1 {TMPPH2 = 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin}, upon reaction with two equivalents of superoxide (O2−) in THF at −40 °C results in the corresponding MnIII–OH complex [MnIII(TMPP2−)(OH)], 2, via the formation of a putative MnIII–peroxynitrite intermediate. Spectral studies and chemical analysis suggest that one equivalent of superoxide ion is consumed to oxidize the metal center of complex 1 leading to [MnIII(TMPP2−)(NO)]+, while the subsequent equivalent reacts with [MnIII(TMPP2−)(NO)]+ to form the corresponding peroxynitrite intermediate. UV-visible and X-band EPR spectroscopic studies suggest the involvement of a MnIV–oxo species in the reaction, which forms through the O–O bond cleavage of the peroxynitrite moiety with concomitant release of NO2. The formation of MnIII–peroxynitrite is further supported by the well-established phenol ring nitration experiment. The released NO2 has been trapped using TEMPO. It should be noted that in cases of MnII–porphyrin complexes, the reaction with superoxide generally proceeds through a SOD-like pathway where the first equivalent of superoxide ion oxidizes the MnII center and itself is reduced to peroxide (O22−), while the subsequent equivalent of superoxide reduces the MnIII center with the release of O2. In contrast, here the second equivalent of superoxide reacts with the MnIII–nitrosyl complex and follows a NOD-like pathway. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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