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

Herein, we report a magnetically retrievable mixed-valent Fe3O4@SiO2/Pd-0/(PdNP)-N-II (5) nanocomposite system for tandem Suzuki coupling/transfer hydrogenation reaction. The nanocomposite 5 was prepared first by making a layer of SiO2 on Fe3O4NP followed by deposition of Pd0 and sorption of PdII 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 Pd0/PdII present onto the surface of nanocomposite 5 was confirmed by XPS technique. Interestingly, the mixed-valent nanocomposite Fe3O4@SiO2/Pd-0/(PdNP)-N-II (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/(PdNP)-N-0 (3) (25% of C) and Fe3O4@SiO2/(PdNP)-N-II (4) (15% of C) nanocomposites. Further, because of the presence of magnetic Fe3O4, the nanocomposite displayed its facile separation from the reaction mixture and reused at least for five catalytic cycles.

Automated summary

A magnetically retrievable mixed-valent Fe3O4@SiO2/Pd-0/(PdNP)-N-II nanocomposite system was reported for tandem Suzuki coupling/transfer hydrogenation reaction, showing high reactivity. The nanocomposite, with magnetic Fe3O4, can be easily separated and reused for at least five catalytic cycles.