Palladium metal nanoparticles stabilized by ionophilic ligands in ionic liquids: synthesis and application in hydrogenation reactions

The reduction of [Pd(acac)(COD)]BF4 (acac = acetylacetonate; COD = 1,5-cyclooctadiene), dissolved in BMI center dot BF4, in the presence of P- or N-containing ionophilic ligands by H-2 yields "soluble" and stable [Pd(0)](n) nanoparticles (NPs). These ionic liquid soluble NPs are active and selective catalysts for the hydrogenation of 1,3-dienes and alkynes under mild reaction conditions. Selectivities up to 87% to cis-2-pentene and 95% conversion were obtained using Pd NPs modified with 1-(3-(diphenylphosphino)propyl)-2,3-dimethyl-1H-imidazol- 3-ium N-bis(trifluoromethylsulfonyl) imide in 1-n-butyl-3-methylimidazolium tetrafluoroborate.