Graphene anchored palladium complex as efficient and recyclable catalyst in the Heck cross-coupling reaction

• A graphenic material was functionalized with palladium(II) molecular compounds.
• The hybrid system was active in the Heck cross-coupling reaction.
• The catalyst converted both vinyl and styril substrates efficiently.
• Samples presented excellent recyclability and air stability.

The immobilization of organometallic molecular catalysts on carbon nanomaterials requires an appropriate synthesis and functionalization methodology to yield active heterogeneous systems. In this work, molecular palladium complexes were synthesized on the aromatic network of a graphenic material employing diazonium chemistry and additional simple modifications to generate a bidentate coordination site for the palladium atoms. The presence of 0.2–0.25 nm palladium(II) species on the surface of the graphenic layers was confirmed by XPS and HRTEM. The modified palladium-graphene hybrid was found to be active as catalyst in the cross-coupling Heck reaction between styrene or n-butyl acrylate with a wide range of aryl bromides substituted with different electron-acceptor and electron-withdrawing groups. The coupled products were obtained in good to excellent yields, at initial TOFs as high as 1.1 s−1. In addition, the catalyst showed excellent cyclability and air stability, and was reused over 8 cycles without any loss of activity.

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