Moore James T, Dorantes Michael J, Pengmei Zihan, Schwartz Timothy M, Schaffner Jacob, Apps Samantha L, Gaggioli Carlo A, Das Ujjal, Gagliardi Laura, Blank David A, Lu Connie C
Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota, 55455-0431, USA.
Institut für Anorganische Chemie, Universität Bonn, Gerhard-Domagk-Str. 1, Bonn, 53121, Deutschland.
Angew Chem Int Ed Engl. 2022 Oct 17;61(42):e202205575. doi: 10.1002/anie.202205575. Epub 2022 Sep 14.
An anionic Rh-Ga complex catalyzed the hydrodefluorination of challenging C-F bonds in electron-rich aryl fluorides and trifluoromethylarenes when irradiated with violet light in the presence of H , a stoichiometric alkoxide base, and a crown-ether additive. Based on theoretical calculations, the lowest unoccupied molecular orbital (LUMO), which is delocalized across both the Rh and Ga atoms, becomes singly occupied upon excitation, thereby poising the Rh-Ga complex for photoinduced single-electron transfer (SET). Stoichiometric and control reactions support that the C-F activation is mediated by the excited anionic Rh-Ga complex. After SET, the proposed neutral Rh intermediate was detected by EPR spectroscopy, which matched the spectrum of an independently synthesized sample. Deuterium-labeling studies corroborate the generation of aryl radicals during catalysis and their subsequent hydrogen-atom abstraction from the THF solvent to generate the hydrodefluorinated arene products. Altogether, the combined experimental and theoretical data support an unconventional bimetallic excitation that achieves the activation of strong C-F bonds and uses H and base as the terminal reductant.
在氢气、化学计量的醇盐碱和冠醚添加剂存在下，用紫光照射时，一种阴离子铑 - 镓配合物催化了富电子芳基氟化物和三氟甲基芳烃中具有挑战性的碳 - 氟键的加氢脱氟反应。基于理论计算，最低未占分子轨道（LUMO）在铑和镓原子之间离域，激发时变为单占据，从而使铑 - 镓配合物具备光诱导单电子转移（SET）的条件。化学计量反应和对照反应支持碳 - 氟活化是由激发态的阴离子铑 - 镓配合物介导的。单电子转移后，通过电子顺磁共振光谱法检测到了所提出的中性铑中间体，其与独立合成样品的光谱相匹配。氘标记研究证实了催化过程中芳基自由基的生成以及它们随后从四氢呋喃溶剂中夺取氢原子以生成加氢脱氟芳烃产物。总之，结合的实验和理论数据支持一种非常规的双金属激发，该激发实现了强碳 - 氟键的活化，并使用氢气和碱作为终端还原剂。
