Synthesis of bipyridine-stabilized, rhodium nanoparticles in non-aqueous ionic liquids: A new efficient approach for arene hydrogenation with nanocatalysts

A new approach to stabilize metal nanoparticles with polynitrogen ligands in ionic liquids (ILs) is described. Zerovalent metal nanospecies in the size range of 2.0 nm were easily prepared in various ionic liquids by chemical reduction of a rhodium salt with an excess amount of sodium borohydride (NaBH,) and efficiently stabilized by 2,2'-bipyridine. The influence of the bipyridine ratio in various ILs according to the nature of the cation-anion association was investigated. These nanocatalysts were evaluated in the hydrogenation of aromatic compounds in ILs under various catalytic conditions (P=140 bar, T = 20-80 degrees C).