Oriented Au nanoplatelets on graphene promote Suzuki-Miyaura coupling with higher efficiency and different reactivity pattern than supported palladium

Facet 111 oriented Au nanoplatelets (20–40nm wide, 3–4nm height) grafted on graphene ( Au ‾ /fl-G) are about three orders of magnitude more efficient than Pd nanoparticles supported on graphene to promote Suzuki-Miyaura coupling. In contrast to Pd catalysis, it is shown here that the product yields in Suzuki-Miyaura coupling catalyzed by Au nanoparticles follow the order chlorobenzene>bromobenzene>iodobenzene. Kinetic studies show that this reactivity order is the result of the poisoning effect of halides for Au that is much higher for I− than Br− and much higher than for Cl−, due to adsorption. This strong iodide adsorption leading to Au catalyst deactivation was predicted by DFT calculations of Au clusters. Au ‾ /fl-G are about one order of magnitude more efficient than small Au nanoparticles (4–6nm) obtained by the polyol method supported on graphene. Our results can have impact in organic synthesis, showing the advantage of Au ‾ /fl-G as catalyst for Suzuki-Miyaura couplings.