Supported palladium nanoparticles as heterogeneous ligand-free catalysts for the Hiyama C–C coupling of vinylsilanes and halobenzenes leading to styrenes

The Hiyama C–C coupling reaction of a wide range of aryl iodides and vinylsilanes has been performed using ligand-free solid catalysts based on supported palladium nanoparticles. Among the supports tested (Mg, TiO2, CeO2 and active carbon), the most active catalysts were those in which palladium is supported on MgO and TiO2. Analogous Pt and Au materials were inefficient to promote this reaction. Leaching tests suggest that there is some contribution of dissolved Pd since Pd in solution has been detected and the scavenging test decreases the initial reaction rate. Although the solid Pd catalysts can be reused, it was, however, observed that they undergo a certain deactivation upon use that can be attributed to several factors including the presence of inorganic compounds on the catalyst, Pd leaching or agglomeration of Pd NPs.

Palladium nanoparticles supported on magnesia is a highly efficient solid, reusable catalyst to promote in the absence of phosphine ligands the coupling of vinylsilanes with iodo- and bromobenzenes to form styrenes.Figure optionsDownload high-quality image (86 K)Download as PowerPoint slideHighlights
► A solid catalyst for the Hiyama C–C coupling is reported.
► The catalyst is recoverable and reusable.
► Palladium leaching contributes partially to the catalysis.
► The reaction mechanism has been supported isolating two palladium complexes with the substrates.