Trends in the chemistry of mono- to multimetal π-arene complexes of chromium and manganese

The preparation and the features of the ring activation in π-arene metal (chromium, manganese) complexes are discussed. The bottom-up approach to the synthesis of σ, π-bi- and multimetal complexes, and the synthesis of cyclometallated and multicyclic complexes from a variety of selected routes are also reviewed. The stereochemical features of such complexes, and their applications in carbon–carbon coupling reactions and metal insertion reactions are highlighted. The redox reactivities and selected applications of (multi)metal π-arene complexes in catalysis and organic synthesis are included. Finally, the extension of the multimetal π-arene complexes to larger assemblies is shown. The importance of arene ring substituents in the basic mononuclear units and their use as bidentate metalloligands, with bidentate amines as linkers, in the construction of polymers, metal organic frameworks, networks (also on nanoparticles or silica supports), is highlighted.