The chameleon-like nature of elusive cobalt-oxygen intermediates in C-H bond activation reactions
- 주제(기타) Chemistry, Inorganic & Nuclear
- 설명문(일반) [Zhou, Anran; Cao, Xuanyu; Chen, Huanhuan; Sun, Dongru; Zhao, Yufen; Wang, Yong] Ningbo Univ, Inst Drug Discovery Technol, Ningbo 315211, Peoples R China; [Zhou, Anran; Cao, Xuanyu; Chen, Huanhuan; Sun, Dongru; Zhao, Yufen; Wang, Yong] Ningbo Univ, Qian Xuesen Collaborat Res Ctr Astrochem & Space, Ningbo 315211, Peoples R China; [Nam, Wonwoo] Ewha Womans Univ, Dept Chem & Nano Sci, Seoul 03760, South Korea
- 등재 SCIE, SCOPUS
- 발행기관 ROYAL SOC CHEMISTRY
- 발행년도 2022
- 총서유형 Journal
- URI http://www.dcollection.net/handler/ewha/000000191171
- 본문언어 영어
- Published As https://doi.org/10.1039/d2dt00224h
- PubMed https://pubmed.ncbi.nlm.nih.gov/35212349
초록/요약
High-valence metal-oxo (M-O, M = Fe, Mn, etc.) species are well-known reaction intermediates that are responsible for a wide range of pivotal oxygenation reactions and water oxidation reactions in metalloenzymes. Although extensive efforts have been devoted to synthesizing and identifying such complexes in biomimetic studies, the structure-function relationship and related reaction mechanisms of these reaction intermediates remain elusive, especially for the cobalt-oxygen species. In the present manuscript, the calculated results demonstrate that the tetraamido macrocycle ligated cobalt complex, Co(O)(TAML) (1), behaves like a chameleon: the electronic structure varies from a cobalt(III)-oxyl species to a cobalt(IV)-oxo species when a Lewis acid Sc3+ salt coordinates or an acidic hydrocarbon attacks 1. The dichotomous correlation between the reaction rates of C-H bond activation by 1 and the bond dissociation energy (BDE) vs. the acidity (pK(a)) was rationalized for the first time by different reaction mechanisms: for normal C-H bond activation, the Co(III)-oxyl species directly activates the C-H bond via a hydrogen atom transfer (HAT) mechanism, whereas for acidic C-H bond activation, the Co(III)-oxyl species evolves to a Co(IV)-oxo species to increase the basicity of the oxygen to activate the acidic C-H bond, via a novel PCET(PT) mechanism (proton-coupled electron transfer with a PT(proton-transfer)-like transition state). These theoretical findings will enrich the knowledge of biomimetic metal-oxygen chemistry.
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