OLIGOPOLYDENTATE LIGANDS FOR HELICES AND METALLACYCLES

Oligopolydentate ligands contain two distinct metal binding sites sepa rated by a spacing group. They are able to form metalla-macrocyclic co mpounds in which the metal ions are an intrinsic part of the cycle. ma y be twisted about the metal-metal axis to give helical complexes. The cycles The use of different metal ions in templating the formation of the helices is discussed together with the properties of the complexe s. More rigid ligands can give rise to the formation of metallacycles with internal cavities which are potential receptor sites.