Dipyrrin based metal complexes: reactivity and catalysis

Sometimes named half-porphyrins, bis-pyrrolic dipyrrin ligands endow their metal complexes with unique properties such as the potential to functionalize the heterocyclic backbone or the meso position and the ability to catalyze interesting chemical transformations. Thus, strategies towards the derivatization of or at the meso group and the use of dipyrrin metal complexes for the formation of a broad range of polypyrrolic derivatives such as 2,2′-bis-dipyrrins, nor-/hetero-corroles and porphynoids have been elaborated. Furthermore, the chelating ability of dipyrrins and the possibility of modifying their steric and electronic characteristics by functionalization can be exploited for the development of numerous complexes featuring appealing properties. Hence, C-H activation/amination, polymerization or oxidation reactions can be catalyzed by dipyrrin metal complexes and classical reagents such as Grignard species, Rh-based or Suzuki-Miyaura catalysts have been revisited by incorporation of dipyrrins in the coordination sphere of the metal cations. This contribution aims to review and illustrate all these aspects, highlighting the potential of these complexes for the design and synthesis of valuable organic compounds and metallo-organic architectures. This Perspective reviews the use of dipyrrin based metal complexes as catalysts and as templates towards polypyrrolic architectures.