SURFACE ORGANOMETALLIC CHEMISTRY ON METALS - A NOVEL AND EFFECTIVE ROUTE TO CUSTOM-DESIGNED BIMETALLIC CATALYSTS

The synthesis, characterization and catalytic properties of new materials obtained by reaction of organometallic complexes of groups IIb, IVa, and VIa with the surface of metallic particles are reviewed. Two types of materials may be obtained by surface organometallic chemistry on metals: metal particles covered with organometallic fragments, and bimetallic particles of predetermined composition. Characterization of the organometallic fragments on the metal particles has demonstrated their thermal stability. These particles covered with surface organometallic fragments are new catalytic materials, highly selective in several reactions such as the hydrogenation of alpha,beta-unsaturated aldehydes, ethyl pyruvate, nitrobenzene, acrylonitrile, and olefins. The bimetallic particles without organometallic fragments are also highly active and selective for a variety of reactions such as hydrogenolysis of various alkanes and hydrogenolysis of esters. For these systems, the concept of ''site isolation'' has been advanced to account for the high selectivity of the reactions.