Rh-Complex Supported on Magnetic Nanoparticles as Catalysts for Hydroformylations and Transfer Hydrogenation Reactions

Herein, we describe a facile protocol for the phosphine complex of Rh anchored on the ultrasmall magnetic nanoparticles for transfer hydrogenation and hydroformylation reactions. A diphenylphosphino-ferrocenylethyl amine was conjugated with dopamine hydrochloride to form dop-Fc, which was then anchored on the surface of magnetic nanoparticles to produce Fe₃O₄@dop-Fc. The prepared materials were complexed with a Rh precursor as a catalytic center. XRD, FTIR, SEM, TEM, and XPS were used to investigate the structure and its reactivity. Rh-complexes of Fe₃O₄@dop-Fc were used to convert terminal olefin to aldehyde using syngas (CO : H₂ 1 : 1) under pressure, obtaining up to 99% selectivity for branched aldehyde. The wide applicability of the Fe₃O₄@dop-Fc−Rh construct was tested for the selective transfer hydrogenations of nitroarene and N-heteroarene. Particularly, quinoline was quantitatively hydrogenated to 1,2,3,4-tetrahydroquinoline(py-THQ) using tetrahydroxydiboron (THDB). Also, the functional group tolerance in the reduction of nitroarene and styrene was evaluated. The robustness of the catalyst was tested by reusing it for multiple cycles.