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Acid Catalysis in the Oxidation of Substrates by Mononuclear Manganese(III)-Aqua Complexes
- Title
- Acid Catalysis in the Oxidation of Substrates by Mononuclear Manganese(III)-Aqua Complexes
- Authors
- Zhang J.; Lee Y.-M.; Seo M.S.; Fukuzumi S.; Nam W.
- Ewha Authors
- 남원우; Shunichi Fukuzumi; 이용민
- SCOPUS Author ID
- 남원우; Shunichi Fukuzumi; 이용민
- Issue Date
- 2022
- Journal Title
- Inorganic Chemistry
- ISSN
- 0020-1669
- Citation
- Inorganic Chemistry vol. 61, no. 17, pp. 6594 - 6603
- Publisher
- American Chemical Society
- Indexed
- SCIE; SCOPUS
- Document Type
- Article
- Abstract
- Acids are known to enhance the reactivities of metal-oxygen intermediates, such as metal-oxo, -hydroperoxo, -peroxo, and -superoxo complexes, in biomimetic oxidation reactions. Although metal-aqua (and metal-hydroxo) complexes have been shown to be potent oxidants in oxidation reactions, acid effects on the reactivities of metal-aqua complexes have never been investigated previously. In this study, a mononuclear manganese(III)-aqua complex, [(dpaq5NO2)MnIII(OH2)]2+ (1; dpaq5NO2 = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-ylacetamidate with an NO2 substituent at the 5 position), which is relatively stable in the presence of triflic acid (HOTf), is used in the investigation of acid-catalyzed oxidation reactions by metal-aqua complexes. As a result, we report a remarkable acid catalysis in the six-electron oxidation of anthracene by 1 in the presence of HOTf; anthraquinone is formed as the product. In the HOTf-catalyzed six-electron oxidation of anthracene by 1, the rate constant increases linearly with an increase of the HOTf concentration. Combined with the observed one-electron oxidation product, anthracene (derivative) radical cation, and the substitution effect at the 5 position of the dpaq ligand in 1 on the rate constants of the oxidation of anthracene, it is concluded that the oxidation of anthracene occurs via an acid-promoted electron transfer (APET) from anthracene to 1. The dependence of the rate constants of the APET from electron donors, including anthracene derivatives, to 1 on the driving force of electron transfer is also shown to be well fitted by the Marcus equation of outer-sphere electron transfer. To the best of our knowledge, this is the first example showing acid catalysis in the oxidation of substrates by metal(III)-aqua complexes. © 2022 American Chemical Society.
- DOI
- 10.1021/acs.inorgchem.2c00430
- Appears in Collections:
- 자연과학대학 > 화학·나노과학전공 > Journal papers
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