Solid‐ and Solution‐Phase Synthesis of a Library of Mixed‐Metal Complexes

A solid‐phase synthesis protocol has been developed for the stepwise assembly of mixed‐metal dinuclear complexes built from chromium, molybdenum and tungsten and a directional bridging ligand. Complexes with all nine possible metal combinations have been prepared on polystyrene/divinylbenzene copolymer employing a metal‐complex‐compatible silyl ether linker. Release of the metal complexes from the polymeric support is accomplished by fluoridolysis under mild conditions. The metal sequence in these complexes is precisely determined by the reaction sequence and is retained under the applied reaction conditions as shown by IR, NMR and UV/Vis spectroscopic analysis of the cleaved soluble products. Additionally, the same complex library has been prepared by conventional solution‐phase synthesis to allow evaluation of the advantages and disadvantages of the solid‐phase synthesis method. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)