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A Manganese(V)-Oxo Complex: Synthesis by Dioxygen Activation and Enhancement of Its Oxidizing Power by Binding Scandium Ion
- Title
- A Manganese(V)-Oxo Complex: Synthesis by Dioxygen Activation and Enhancement of Its Oxidizing Power by Binding Scandium Ion
- Authors
- Hong, Seungwoo; Lee, Yong-Min; Sankaralingam, Muniyandi; Vardhaman, Anil Kumar; Park, Young Jun; Cho, Kyung-Bin; Ogura, Takashi; Sarangi, Ritimukta; Fukuzumi, Shunichi; Nam, Wonwoo
- Ewha Authors
- 남원우; Shunichi Fukuzumi; 이용민
- SCOPUS Author ID
- 남원우; Shunichi Fukuzumi; 이용민
- Issue Date
- 2016
- Journal Title
- JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
- ISSN
- 0002-7863
- Citation
- JOURNAL OF THE AMERICAN CHEMICAL SOCIETY vol. 138, no. 27, pp. 8523 - 8532
- Publisher
- AMER CHEMICAL SOC
- Indexed
- SCIE; SCOPUS
- Document Type
- Article
- Abstract
- A mononuclear non-heme manganese(V)-oxo complex, [Mn-V(O)(TAML)](-) (1), was synthesized by activating dioxygen in the presence of olefins with weak allylic C-H bonds and characterized structurally and spectroscopically. In mechanistic studies, the formation rate of 1 was found to depend on the allylic C-H bond dissociation energies (BDEs) of olefins, and a kinetic isotope effect (KIE) value of 16 was obtained in the reactions of cyclohexene and cyclohexene-d(10). These results suggest that a hydrogen atom abstraction from the allylic C-H bonds of olefins by a putative Mn-IV-superoxo species, which is formed by binding O-2 by a high-spin (S = 2) [Mn-III(TAML)](-) complex, is the rate-determining step. A Mn(V)-oxo complex binding Sc3+ ion, [Mn-V(O)(TAML)](-)-(Sc3+) (2), was also synthesized in the reaction of 1 with Sc3+ ion and then characterized using various spectroscopic techniques. The binding site of the Sc3+ ion was proposed to be the TAML ligand, not the Mn-O moiety, probably due to the low basicity of the oxo group compared to the basicity of the amide carbonyl group in the TAML ligand. Reactivity studies of the Mn(V)-oxo intermediates, 1 and 2, in oxygen atom transfer and electron-transfer reactions revealed that the binding of Sc3+ ion at the TAML ligand of Mn(V)-oxo enhanced its oxidizing power with a positively shifted one-electron reduction potential (Delta E-red = 0.70 V). This study reports the first example of tuning the second coordination sphere of high-valent metal-oxo species by binding a redox-inactive metal ion at the supporting ligand site, thereby modulating their electron-transfer properties as well as their reactivities in oxidation reactions.
- DOI
- 10.1021/jacs.6b03874
- Appears in Collections:
- 자연과학대학 > 화학·나노과학전공 > Journal papers
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