Preparation of alkanethiolate-protected palladium nanoparticles and their size dependence on synthetic conditions

Palladium nanoparticles protected by alkanethiolates with a core diameter 1.3-3.9 nm were synthesized by the treatment of PdCl2(CH3CN)(2) with tetraalkylammonium bromide and LiBEt3H in THF, followed by the addition of alkanethiols. The mean size and its deviation as observed by transmission electron microscopy varied in relation to changes in the reaction conditions involving variables such as the ammonium salt, the molar ratio of the reactants, the reaction time, and the alkanethiol. Smaller particles were obtained when the ratio of [PdCl2(CH3CN)(2)] to other reagents was decreased, the reaction time was increased, and a long alkanethiol was used.