A magnetically retrievable mixed-valent Fe3O4@SiO2/Pd0/PdII nanocomposite exhibiting facile tandem Suzuki coupling/transfer hydrogenation reaction

Abstract

Herein, we report a magnetically retrievable mixed-valent Fe3O4@SiO2/Pd0/PdIINP (5) nanocomposite system for tandem Suzuki coupling/transfer hydrogenation reaction. The nanocomposite 5 was prepared first by making a layer of hbox {SiO}_{2} on hbox {Fe}_{3}hbox {O}_{4}hbox {NP} followed by deposition of hbox {Pd}^{0} and sorption of hbox {Pd}^{mathrm{II}} ions successively onto the surface of Fe3O4@SiO2NP. The nanocomposite was characterized by powder XRD, electron microscopy (SEM-EDS and TEM-EDS) and XPS spectroscopy techniques. The mixed-valent hbox {Pd}^{0}/hbox {Pd}^{mathrm{II}} present onto the surface of nanocomposite 5 was confirmed by XPS technique. Interestingly, the mixed-valent nanocomposite Fe3O4@SiO2/Pd0/PdIINP (5) exhibited tandem Suzuki coupling/transfer hydrogenation reaction during the reaction of aryl bromide with aryl boronic acid (90% of C). The nanocomposite 5 displayed much better reactivity as compared to the monovalent Fe3O4@SiO2/Pd0NP (3) (25% of C) and Fe3O4@SiO2/PdIINP (4) (15% of C) nanocomposites. Further, because of the presence of magnetic hbox {Fe}_{3}hbox {O}_{4}, the nanocomposite displayed its facile separation from the reaction mixture and reused at least for five catalytic cycles.