Palladium nanoparticles

Preparative Methods: a 0.6 mM solution of H2PdCl4 containing 40% ethanol and 100 monomeric molar equivalent of PVP [poly(N-vinyl-2-pyrrolidone)] (average Mw = 6000–10000) was refluxed under N2 to obtain monodispersed Pd nanoparticles, presumably with a mean diameter of ca. 17 Å, according to the method in reference 2. The H2PdCl4 solution was prepared from PdCl2 and aq HCl. During the reduction, the yellow color changes to light brown where no precipitation was observed. The solvent was evaporated off to remove HCl and a large amount of water, and the resulting residue was re-dissolved in 98% EtOH (or in MeOH) for hydrogenolysis. Excess amounts of PVP further stabilize the palladium metal clusters; this is especially important if the reagent is used in the reaction with solid supported compounds. For more background research on heterogeneous catalysts in organic reactions, see references 3-6.