Reactions of arene replacement in transition metal complexes

Replacement of an aromatic ligand is a typical reaction of transition metal complexes and understanding of its general features is crucial for their successful application. This review summarizes thermodynamic and kinetic factors that affect the arene replacement. From the thermodynamic viewpoint, electron-poor arenes typically form less stable complexes and therefore are more easily replaced. From the kinetic viewpoint, arene displacement is initiated by nucleophilic attack of the incoming ligand and therefore high positive charge of the metal and its spatial accessibility, as well as donor properties of the incoming ligands facilitate the process. Arene displacement can be accelerated by heating, irradiation or by addition of polar, coordinating solvents. Transition metals of groups 6-8 usually form relatively stable and inert arene complexes, while complexes of metals of groups 4-5 and 9-11 are labile and undergo arene replacement in mild conditions. The application of the arene displacement reaction for the synthesis of various organometallic compounds and generation of catalytically active species is also discussed in the review. (C) 2020 Elsevier B.V. All rights reserved.