HETEROMETAL ALKOXIDES — A NOVEL SERIES OF STABLE POLYMETALLIC COORDINATION COMPOUNDS

The synthesis of a novel series of bimetallic alkoxides during the last three decades has been followed by a successful synthesis during the past five years of a series of intriguingly stable heterometal alkoxides containing three or four different metal atoms in the same molecular species.

The increasing importance of the use of mixtures of two and more than two metal alkoxides as precursors for the preparation of a wide variety of novel ceramic materials by the SOLUTION - SOL-GEL (S-S-G) process has led to the possibility of molecularly designing a heterometal alkoxide corresponding to the composition of a targetted final ceramic. This has been made feasible by the extraordinary stability of the framework of heterometal alkoxides, which appears to remain intact during the initial hydrolysis reactions involved in the S-S-G process.

The characterization (by sophisticated physico-chemical techniques including X-ray crystal structure eludication in a few cases) of these heterometal alkoxides appears to have added a new class of heterometal coordination systems which appear to be uniquely stable without the presence of metal-metal bonds or auxiliary ligands like Co, etc., generally required for stabilizing polymetallic systems known so far.