Suppr超能文献

揭示在以杂原子为中心的自由基生成过程中共价连接的双自由基阴离子的本质:极性匹配的质子耦合电子转移途径的证据。

Revealing the nature of covalently tethered distonic radical anions in the generation of heteroatom-centered radicals: evidence for the polarity-matching PCET pathway.

作者信息

Fu Kang, Yang Xihui, Yu Zhiyou, Song Lijuan, Shi Lei

机构信息

School of Chemistry and Chemical Engineering, School of Science(shenzhen), Harbin Institute of Technology Harbin 150001 China

出版信息

Chem Sci. 2024 Jun 28;15(31):12398-12409. doi: 10.1039/d4sc02602k. eCollection 2024 Aug 7.

Abstract

Recognition of the intermediacy and regulation of reactivity patterns of radical intermediates in radical chemistry have profound impacts on harnessing and developing the full potential of open-shell species in synthetic settings. In this work, the possibility of formation of O/N-X intermediates from Brønsted base covalently tethered carbonyl hypohalites (BCTCs) for the generation of heteroatom-centered radicals has certainly been excluded by NMR experiments and density functional theory calculations. Instead, the spectroscopic analyses reveal that the BCTCs serve as precursors of tether-tunable distonic radical anions (TDRAs) which have been unequivocally substantiated to be involved in the direct cleavage of O/N-H bonds to generate the corresponding heteroatom-centered radicals. Meanwhile, a deep insight into the properties and reactivities of the resulting TDRAs indicates that the introduction of a tethered Brønsted base on the parent open-shell species reinforces their stabilities and leads to a reversal of electrophilicity. Moreover, the dual descriptor values and electrophilicity indices are calculated based on eleven reported radical reactions involving various electrophilic/nucleophilic radical species, further confirming their validity in the prediction of the polar effect and the polarity-matching consistency between nucleophilic TDRAs and protic O/N-H bonds. The additional halogen-free experiments mediated by the combination of phthaloyl peroxide and TEMPO also prove the feasibility of the TDRA-assisted philicity-regulation approach. Lastly, detailed intrinsic bond orbital (IBO) and Hirschfeld spin population analyses are employed to elucidate that the H-atom abstraction processes are the polarity-matching proton-coupled electron transfer (PCET) pathways, with a degree of oxidative asynchronicity.

摘要

认识到自由基化学中自由基中间体反应性模式的中介作用和调控,对在合成环境中充分利用和开发开壳物种的全部潜力具有深远影响。在这项工作中,通过核磁共振实验和密度泛函理论计算,肯定排除了由布朗斯特碱共价连接的羰基次卤酸盐(BCTCs)形成O/N-X中间体以生成以杂原子为中心的自由基的可能性。相反,光谱分析表明,BCTCs作为可通过连接基团调节的双自由基阴离子(TDRAs)的前体,已明确证实其参与O/N-H键的直接裂解以生成相应的以杂原子为中心的自由基。同时,对所得TDRAs的性质和反应性的深入研究表明,在母体开壳物种上引入连接的布朗斯特碱增强了它们的稳定性,并导致亲电性的反转。此外,基于涉及各种亲电/亲核自由基物种的11个已报道的自由基反应计算了双描述符值和亲电性指数,进一步证实了它们在预测极性效应以及亲核TDRAs与质子O/N-H键之间的极性匹配一致性方面的有效性。由邻苯二甲酰过氧化物和TEMPO组合介导的额外无卤实验也证明了TDRA辅助亲电性调节方法的可行性。最后,采用详细的本征键轨道(IBO)和赫希菲尔德自旋布居分析来阐明H原子抽取过程是极性匹配的质子耦合电子转移(PCET)途径,具有一定程度的氧化异步性。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/7410/11304808/64e712b188d4/d4sc02602k-f1.jpg

文献AI研究员

20分钟写一篇综述,助力文献阅读效率提升50倍。

立即体验

用中文搜PubMed

大模型驱动的PubMed中文搜索引擎

马上搜索

文档翻译

学术文献翻译模型,支持多种主流文档格式。

立即体验