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