COORDINATION CHEMISTRY IN ZEOLITES

Researchers have devised several procedures for synthesizing transitio n metal ion (TMI) complexes in zeolite cavities and channels. Two main routes have been envisaged: synthesis with a preformed complex and co mplex assembly in the zeolite. An overview of the different preparatio n methods and of the TMI-complexes, encaged in zeolites, is given. The se complexes have been mainly studied in zeolite Y. The zeolite is a n on-coordinating anion, a solvent, or a ligand. It reduces the mobility of the complexes and provides chemisorption sites. Future development s will comprise the use of wide-pore zeolites and zeotypes (e.g., VPI- 5, MCM-41, hexagonal faujasite) and the design of optically active sur faces. Furthermore, there is a need for quantification in general and for selectively synthesizing one type of complex.