Magnetic mesoporous SBA‐15 functionalized with a NHC Pd(II) complex: An efficient and recoverable nanocatalyst for Hiyama reaction

Magnetite nanoparticles (MNPs) were covered by a silica shell and then embedded into mesoporous silica (SBA‐15). Magnetic mesoporous silica (Fe₃O₄@SiO₂‐SBA) was then reacted with 3‐chloropropyltriethoxysilane (CPTS), sodium salt of imidazole and 2‐bromopyridine to give Fe₃O₄@SiO₂‐SBA functionalized with 3‐(pyridin‐2‐yl)‐1H‐imidazol‐3‐ium‐propyl (PIP) as a supported pincer ligand for Pd(II). The functionalized magnetic mesoporous silica were then treated with t‐BuOK at −80 °C in THF and then reacted with [PdCl₂(SMe₂)₂] to give supported Pd(II)‐carbene complex containing C,N‐bidentate ligand. The chloride ions were then exchanged by bromide ions using a NaBr solution of diethylether/acetone mixture. The prepared catalyst was characterized with, FT‐IR, thermo gravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), Brunauer–Emmett–Teller surface area measurement (S_BET), energy dispersive X‐ray analysis (EDX) and wide angle X‐ray diffraction spectroscopy (XRD). The prepared magnetic catalyst was effectively used in the coupling reaction of triethoxyphenylsilane with aryl halides (Hiyama reaction) in the presence of a base. The reaction parameters such as solvents, amount of catalyst, base and temperature were optimized. The catalyst was then magnetically decanted, washed, and reused several times.