Sulfoxide-Stabilized Giant Palladium Clusters in Catalyzed Oxidations

摘要

Large transition metal clusters are gaining increasing attention as research targets for several reasons. Their existence on the borderline between molecular states with discrete quantum energy levels and the actual metallic state with its typical bulk properties raises the interest of not only physicists and material scientists but also of chemists working in the field of catalysis. Since these species are also on the borderline between homogeneous and heterogeneous catalysts, they may perhaps havetypical characteristics of both. The feasibility of preparing platinum group transition metal clusters and colloids by reducing inorganic complexes in the presence of an appropiate stabilizing ligand such as phenanthroline has been demonstrated by Moiseev et al. and Schmid et al. Phosphanes were also shown to be useful ligands for this purpose. This communication describes the first example, to our knowledge, of sulfoxide-stabilized giant palladium clusters.