Holtrop Flip, Jupp Andrew R, Kooij Bastiaan J, van Leest Nicolaas P, de Bruin Bas, Slootweg J Chris
Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090 GD, Amsterdam, The Netherlands.
Angew Chem Int Ed Engl. 2020 Dec 1;59(49):22210-22216. doi: 10.1002/anie.202009717. Epub 2020 Oct 1.
Frustrated Lewis pairs (FLPs) are well known for their ability to activate small molecules. Recent reports of radical formation within such systems indicate single-electron transfer (SET) could play an important role in their chemistry. Herein, we investigate radical formation upon reacting FLP systems with dihydrogen, triphenyltin hydride, or tetrachloro-1,4-benzoquinone (TCQ) both experimentally and computationally to determine the nature of the single-electron transfer (SET) events; that is, being direct SET to B(C F ) or not. The reactions of H and Ph SnH with archetypal P/B FLP systems do not proceed via a radical mechanism. In contrast, reaction with TCQ proceeds via SET, which is only feasible by Lewis acid coordination to the substrate. Furthermore, SET from the Lewis base to the Lewis acid-substrate adduct may be prevalent in other reported examples of radical FLP chemistry, which provides important design principles for radical main-group chemistry.
受阻路易斯酸碱对（FLPs）以其活化小分子的能力而闻名。近期关于此类体系中自由基形成的报道表明，单电子转移（SET）可能在其化学反应中发挥重要作用。在此，我们通过实验和计算研究了FLP体系与氢气、三苯基氢化锡或四氯-1,4-苯醌（TCQ）反应时的自由基形成情况，以确定单电子转移（SET）事件的本质，即是否直接向B(CF)进行单电子转移。氢气和PhSnH与典型的P/B FLP体系的反应并非通过自由基机制进行。相比之下，与TCQ的反应通过单电子转移进行，而这只有通过路易斯酸与底物的配位才可行。此外，在其他已报道的自由基FLP化学实例中，从路易斯碱到路易斯酸-底物加合物的单电子转移可能很普遍，这为自由基主族化学提供了重要的设计原则。
