Magnetic Mesoporous SBA‐15 Functionalized with a NHC Pd(II) Complex: An Efficient and Recoverable Nanocatalyst for Hiyama Reaction

Abstract

Magnetite nanoparticles (MNPs) were covered by a silica shell and then embedded into mesoporous silica . Magnetic mesoporous silica (Fe 3 O 4 @SiO 2 -SBA) was then reacted with 3chloropropyltriethoxysilane (CPTS), sodium salt of imidazole and 2-bromopyridine to give Fe 3 O 4 @SiO 2 -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 À 80°C in THF and then reacted with [PdCl 2 (SMe 2 ) 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.

Functionalized Silicas for Metal‐Free and Metal‐Based Catalytic Applications: A Review in Perspective of Green Chemistry

“…It is worth to note that silica supported ILs can be prepared in the form of quaternary ammonium salts . NHCs, the useful ligands for the stabilization of low coordinate metal complexes for various catalytic applications, can be anchored on silica using halo FSs The chemical structures of recently reported ILs, quaternary ammonium salts and NHCs that derived from halo FSs are given in Figure .…”

“…In spite of displaying very good catalytic activity, these palladium(0)‐FS catalysts demonstrate excellent reusability because the leaching of palladium(0) active sites is greatly inhibited which befalls through the strong chemical interaction between palladium(0) and FSs. Like palladium(0) FS catalysts, palladium(II) ions immobilized on FSs are also effectual as the catalysts for Suzuki‐Miyaura coupling, Heck‐Mizoroki coupling and Hiyama coupling . Interestingly, N. Vucetic et al have dispersed palladium(II) on IL FS which exhibits the best catalytic activity (turnover frequency (TOF)=22000 h −1 ) than all other catalysts reported in the literature for Heck‐Mizoroki coupling befalling between iodobenzene and methacrylate in presence of a base.…”

Immobilized Pd metal‐complex on polymeric resin with high surface areas for recyclable catalyst: Effect of the immobilization method on nature of palladium species

“…Different inorganic and organic solids have been used to immobilize coordination compounds, such as SiO 2 , 1,[12][13][14][15][16] and Fe 3 O 4 particles, 17,18 among others. Commonly, these inorganic matrixes needed surface grafting with linkers molecules to provide a covalent anchoring point for the immobilization of coordination compounds, which are generally focused on the MS approach.…”

Magnetite@MCM‐41 nanoparticles as support material for Pd‐N‐heterocyclic carbene complex: A magnetically separable catalyst for Suzuki–Miyaura reaction

“…[34,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] The C-C bond formation reaction is a critical synthesis procedure in synthesizing natural products, agrochemicals, biologically active compounds, and pharmaceuticals. [33,34,38,44,48,50,[54][55][56] Although structurally similar catalysts exist in the literature, Pd complex of NHC ligand attached to the supporting material via the OH-group is not available in the literature. We synthesized this type of catalyst with the intelligent guess that such type catalyst maybe leads to high catalytic activity on the Suzuki-Miyaura reactions.…”