Mechanism of a Suzuki-Type Homocoupling Reaction Catalyzed by Palladium Nanocubes

The trans-2-phenylvinylboronic acid homocoupling reaction catalyzed by palladium nanocubes (Pd-NCs) was investigated by kinetics, spectroscopy, and poisoning experiments. The reaction was evidenced to be sensitive to the presence of the base, which acts synergistically with the substrate molecules and assists the leaching of Pd oxide (PdOx) species to the reaction medium. This species catalyzes the homocoupling reaction through the formation of Pd-O-x-B(OH)(2)R pretransmetalation intermediates, via coordination with the vinylboronic acid molecules, involving an oxo-palladium-type interaction. The reaction rate was not enhanced by the saturation of the reaction medium with O-2, which is due to the oxidized nature of the Pd-NC surface.