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Preparation and Characterization of a Formally NiIV-Oxo Complex with a Triplet Ground State and Application in Oxidation Reactions br
- Title
- Preparation and Characterization of a Formally NiIV-Oxo Complex with a Triplet Ground State and Application in Oxidation Reactions br
- Authors
- Karmalkar, Deepika G.; Larson, Virginia A.; Malik, Deesha D.; Lee, Yong-Min; Seo, Mi Sook; Kim, Jin; Vasiliauskas, Dovydas; Shearer, Jason; Lehnert, Nicolai; Nam, Wonwoo
- Ewha Authors
- 남원우; 이용민; 서미숙; 김진
- SCOPUS Author ID
- 남원우; 이용민; 서미숙; 김진
- Issue Date
- 2022
- Journal Title
- JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
- ISSN
- 0002-7863
1520-5126
- Citation
- JOURNAL OF THE AMERICAN CHEMICAL SOCIETY vol. 144, no. 49, pp. 22698 - 22712
- Publisher
- AMER CHEMICAL SOC
- Indexed
- SCIE; SCOPUS
- Document Type
- Article
- Abstract
- High-valent first-row transition-metal-oxo complexes are impor-tant intermediates in biologically and chemically relevant oxidative transformations of organic molecules and in the water splitting reaction in (artificial) photosynthesis. While high-valent Fe- and Mn-oxo complexes have been characterized in detail, much less is known about their analogues with late transition metals. In this study, we present the synthesis and detailed characterization of a unique mononuclear terminal Ni-O complex. This compound, [Ni(TAML)(O)(OH)]3-, is characterized by an intense charge -transfer (CT) band around 730 nm and has an St = 1 ground state, as determined by magnetic circular dichroism spectroscopy. From extended X-ray absorption fine structure (EXAFS), the Ni-O bond distance is 1.84 angstrom. Ni K edge XAS data indicate that the complex contains a Ni(III) center, which results from an unusually large degree of Ni-O pi-bond inversion, with one hole located on the oxo ligand. The complex is therefore best described as a low-spin Ni(III) complex (S = 1/2) with a bound oxyl (O center dot-) ligand (S = 1/2), where the spins of Ni and oxyl are ferromagnetically coupled, giving rise to the observed St = 1 ground state. This bonding description is roughly equivalent to the presence of a Ni-O single (sigma) bond. Reactivity studies show that [Ni(TAML)(O)(OH)]3- is a strong oxidant capable of oxidizing thioanisole and styrene derivatives with large negative rho values in the Hammett plot, indicating its electrophilic nature. The intermediate also shows high reactivity in C-H bond activation of hydrocarbons with a kinetic isotope effect of 7.0(3) in xanthene oxidation.
- DOI
- 10.1021/jacs.2c10196
- Appears in Collections:
- 자연과학대학 > 화학·나노과학전공 > Journal papers
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