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Generation, Spectroscopic Characterization, and Computational Analysis of a Six-Coordinate Cobalt(III)-Imidyl Complex with an Unusual S = 3/2 Ground State that Promotes N-Group and Hydrogen Atom-Transfer Reactions with Exogenous Substrates
- Title
- Generation, Spectroscopic Characterization, and Computational Analysis of a Six-Coordinate Cobalt(III)-Imidyl Complex with an Unusual S = 3/2 Ground State that Promotes N-Group and Hydrogen Atom-Transfer Reactions with Exogenous Substrates
- Authors
- Yang; Jindou; Tripodi; Guilherme L.; Derks; Max T. G. M.; Seo; Mi Sook; Lee; Yong-Min; Southwell; Kendal W.; Shearer; Jason; Roithová; Jana; Nam; Wonwoo
- Ewha Authors
- 남원우; 이용민; 서미숙
- SCOPUS Author ID
- 남원우; 이용민; 서미숙
- Issue Date
- 2023
- Journal Title
- Journal of the American Chemical Society
- ISSN
- 0002-7863
- Citation
- Journal of the American Chemical Society vol. 145, no. 48, pp. 26106 - 26121
- Publisher
- American Chemical Society
- Indexed
- SCIE; SCOPUS
- Document Type
- Article
- Abstract
- We report the synthesis and characterization of a mononuclear nonheme cobalt(III)-imidyl complex, [Co(NTs)(TQA)(OTf)]+ (1), with an S = 3/2 spin state that is capable of facilitating exogenous substrate modifications. Complex 1 was generated from the reaction of CoII(TQA)(OTf)2 with PhINTs at −20 °C. A flow setup with ESI-MS detection was used to explore the kinetics of the formation, stability, and degradation pathway of 1 in solution by treating the Co(II) precursor with PhINTs. Co K-edge XAS data revealed a distinct shift in the Co K-edge compared to the Co(II) precursor, in agreement with the formation of a Co(III) intermediate. The unusual S = 3/2 spin state was proposed based on EPR, DFT, and CASSCF calculations and Co Kβ XES results. Co K-edge XAS and IR photodissociation (IRPD) spectroscopies demonstrate that 1 is a six-coordinate species, and IRPD and resonance Raman spectroscopies are consistent with 1 being exclusively the isomer with the NT ligand occupying the vacant site trans to the TQA aliphatic amine nitrogen atom. Electronic structure calculations (broken symmetry DFT and CASSCF/NEVPT2) demonstrate an S = 3/2 oxidation state resulting from the strong antiferromagnetic coupling of an •NTs spin to the high-spin S = 2 Co(III) center. Reactivity studies of 1 with PPh3 derivatives revealed its electrophilic characteristic in the nitrene-transfer reaction. While the activation of C-H bonds by 1 was proved to be kinetically challenging, 1 could oxidize weak O-H and N-H bonds. Complex 1 is, therefore, a rare example of a Co(III)-imidyl complex capable of exogenous substrate transformations. © 2023 American Chemical Society
- DOI
- 10.1021/jacs.3c08117
- Appears in Collections:
- 자연과학대학 > 화학·나노과학전공 > Journal papers
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