Discrete Polyoxopalladates as Molecular Precursors for Supported Palladium Metal Nanoparticles as Hydrogenation Catalysts.

We have used discrete polyoxopalladates(II) (POPs) of the MPdX nanocube- and PdX nanostar-types (M = central metal ion, X = capping group) as molecular precursors (diameter ca. 1 nm) for the formation of supported (SBA-15) metallic nanoparticles. These materials proved to be highly active in the hydrogenation of o-xylene. The characterization of such hydrogenation catalysts revealed that the average size of the resulting alloy particles is quite uniform with diameters ranging from 1 to 3 nm (indicating little to no agglomeration). The central transition-metal ion M (Mn, Fe, Co, Ni, Cu, Zn, Pd) in the POP structure and also the nature of the capping group (AsO, SeO, PO, phenyl-AsO) influence the resulting catalytic performance.