Axial Chirality in Square-Planar Metal Complexes

Metal complexes with a square-planar arrangement of ligands are frequently found for the late Transition Metals. The incorporation of C 1 -symmetrical planar ligands (e.g. nucleophilic carbenes) in an orientation perpendicular to the square-plane of the complex leads to various isomers which are characterized by means of an axis of chirality employing the well established Cahn-Ingold-Prelog -R/S-nomenclature.