More than just a support: Graphene as a solid-state ligand for palladium-catalyzed cross-coupling reactions

Abstract

While the primary role of supports in catalysis has been to anchor metal particles to prevent sintering, supports can also activate catalytic processes. We report computational and experimental results that provide a fundamental understanding of how a graphene support may activate both oxidative and reductive reaction steps in the catalytic cycle of Suzuki-Miyaura palladium-catalyzed cross-coupling reactions. Theoretical investigations reveal that the high catalytic activity is linked to the ability of a graphene support to act as both an efficient charge donor and acceptor in oxidation and reduction reaction steps. We compare the activation energy and turn over frequency for a series of supported and homogeneous catalysts and find that exposing palladium-graphene to defect inducing microwave radiation results in dramatically lower activation energies and higher turnover frequencies. These results explain why a defected graphene support may catalyze reaction steps that require both charge donation, and charge acceptance.