Beryllium compounds for the carbon–halogen bond activation of phenyl halides: the role of non-innocent ligands

Abstract

Beryllium is a metallomimetic main-group element, i.e., it behaves similarly to transition metals (TMs) in some bond activation processes. To investigate the ability of Be compounds to activate C–X bonds (X = F–I), we have computationally investigated, using DFT methods, the reaction of (CAAC)₂Be (CAAC = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) and a series of five-membered heterocyclic beryllium bidentate ligands with phenyl halides. We have analysed all plausible reaction mechanisms and our results show that, after the initial C–X oxidative addition, migration of the phenyl group occurs towards the less electronegative heteroatom. Our theoretical study highlights the important role of bidentate non-innocent ligands in providing the required electrons for the initial Ph–X oxidative addition. In contrast, the monodentate ligand, CAAC, does not favour this oxidative addition.