Calixarenes as cluster keepers the isolation of multinuclear metal complexes

Abstract

Phenolic calixarenes in particular exhibit a tendency to form multinuclear metal ion complexes, many of which can be regarded as hydrolytic or anionbridged clusters enveloped within a lipophilic calixarene sheath, justifying the designation of the calixarenes as "cluster keepers". Of the factors which determine the nuclearity of the clusters, the calixarene ring size and the capacity of phenoxide donors to act as bridges are obviously important but another which offers prospects for considerable development of known cluster chemistry is that of the substitution of S for CH2 to give the family of thiacalixarenes. Clusters involving up to 10 metal ions are now well-characterised, many of unique geometry and properties. © 2007 Springer.