Highly active, durable and recyclable ordered mesoporous magnetic organometallic catalysts for promoting organic reactions in water

Abstract

A new strategy of bonding organometallics to an MCM-41 thin layer coated onto Fe₃O₄ microspheres with strong magnetism, denoted as M–PPh₂-MCM-41@SiO₂@Fe₃O₄, where M = Pd(II) and Rh(I), has been developed for the immobilization of homogeneous catalysts. In comparison with the traditional M–PPh₂-MCM-41 catalysts with irregular shapes and the M–PPh₂-SiO₂@Fe₃O₄ without an ordered mesoporous structure, the current catalysts exhibited much higher activities for various water-based Suzuki, Sonogashira and Miyaura–Michael organic reactions, due to the high dispersion of active sites and the uniform catalyst particles with short-ordered mesopores favoring reactant diffusion and adsorption. Their catalytic efficiencies are comparable with those of the homogeneous catalysts, and they could be easily recycled for reuse by simply applying an external magnet.