Department of Chemistry, Beijing Normal University, Xin-wai-da-jie No. 19, Beijing 100875, China.
Laboratory of Beam Technology and Energy Materials, Advanced Institute of Natural Sciences, Beijing Normal University, Zhuhai 519087, China.
J Phys Chem Lett. 2023 Jul 6;14(26):6187-6192. doi: 10.1021/acs.jpclett.3c01049. Epub 2023 Jun 28.
Identification of radical intermediates for the catalytic functionalization of alkanes offers a number of unique challenges and has recently raised a controversial issue concerning the subtle role of chlorine versus alkoxy radicals in cerium photocatalysis. This study is an attempt to settle the controversy within the theoretical frameworks of Marcus electron transfer and transition state theory. Co-function mechanisms were proposed together with a scheme of kinetic evaluations to account for ternary dynamic competition among photolysis, back electron transfer, and hydrogen atom transfer (HAT). Cl•-based HAT has been proven to initially control the early dynamics of the photocatalytic transformation on the picosecond to nanosecond time scale, which is subsequently taken over by a postnanosecond event of alkoxy radical-mediated HAT. The theoretical models developed herein provide a uniform understanding of the continuous time dynamics of photogenerated radicals to address some paradoxical arguments in lanthanide photocatalysis.
烷烃的催化功能化中自由基中间体的鉴定带来了一些独特的挑战，最近在铈光催化中氯自由基与烷氧基自由基的微妙作用方面引起了争议。本研究试图在 Marcus 电子转移和过渡态理论的理论框架内解决这一争议。提出了共函数机制，并提出了一个动力学评估方案，以解释光解、反向电子转移和氢原子转移 (HAT) 之间的三元动态竞争。基于 Cl•的 HAT 已被证明最初控制光催化转化的早期动力学，该动力学在皮秒到纳秒的时间尺度上控制，随后被烷氧基自由基介导的 HAT 的纳秒后事件所接管。本文开发的理论模型提供了对光生自由基连续时间动力学的统一理解，以解决镧系元素光催化中一些矛盾的论点。
