Active and reusable Pd(II) organometallic catalyst covalently bonded to mesoporous silica nanospheres for water-medium organic reactions

A novel heterogenized Pd(II) organometallic catalyst was synthesized by coordinating Pd(II) ions with PPh2-functionalized silica nanospheres containing an ordered mesoporous structure. This catalyst exhibited higher activity and selectivity in a water-medium for the Barbier, Sonogashira and Ullmann reactions than the corresponding catalyst bonded to MCM-41. This was found to be due to high surface area, ordered mesopores and short pore channels, which facilitated the diffusion and adsorption of reactant molecules. This catalyst displayed comparable efficiencies with the homogeneous catalyst, Pd(PPh2)(3)Cl-2 and could be easily recycled and used repetitively. It showed good potential in industrial applications owing to the reduced cost and the diminished environmental pollution from either the organic solvents as reaction media or the heavy metallic ions.