Development of Metallacrown Ethers: A New Class of Metal Clusters

Crown ethers have been used for over twenty years as selective binding agents for alkali metal and alkaline earth ions. Although there have been many modifications to the crown ether core, none is so dramatic as to substitute heteroatoms into the positions normally occupied by carbon atoms. In this article we describe a new class of metal clusters which incorporate trivalent metal ions and nitrogen atoms into molecules that structurally and functionally mimic the behavior of crown ethers. These metallacrown ethers can be prepared in high yield in only a couple of steps and lead to molecules that may have utility in analytical chemistry, catalysis and new polymeric materials.