IR STUDIES AND HYDROGENATION CATALYTIC ACTIVITY OF HETEROGENEOUS CATALYSTS PREPARED BY THERMAL TREATMENTS OF A FACE-BRIDGED TRIRUTHENIUM CARBONYL CLUSTER SUPPORTED ON SILICA AND ALUMINA

The interaction of the cluster complex [Ru-3(mu-H)(mu(3),eta(2)-ampy)( CO)(9)] (1) (ampy = 2-amino-6-methylpyridinate) with silica and gamma- alumina at different temperatures (under vacuum and under nitrogen) ha s been studied by IR spectroscopy. These studies have shown that the p resence of the face-bridging ligand ampy in complex 1 does not prevent cluster fragmentation on the support surface, since thermal treatment s of these systems just above room temperature lead to mononuclear rut henium surface species. The solids obtained by different thermal treat ments of the 1-SiO2 and 1-Al2O3 systems were tested as catalyst precur sors for the hydrogenation of phenylacetylene, resulting in: (i) the s ilica-based solids are better catalyst precursors than the alumina-bas ed ones, (ii) the solids with mononuclear surface species are more act ive than those with cluster surface species, (iii) all the supported s ystems are worse catalysts than complex 1 under homogeneous conditions .