The rhodium complex of bis(diphenylphosphinomethyl)dopamine-coated magnetic nanoparticles as an efficient and reusable catalyst for hydroformylation of olefins

Abstract

A new bis(diphenylphosphinomethyl)dopamine (bpd) ligand has been prepared and anchored on the surface of magnetic nanoparticles (MNPs). The obtained ligand and the surface functionalized nanoparticles of type MNP@bpd have been characterized by various analytical techniques, such as NMR, IR, TEM, XRD, and VSM. TEM shows homogeneous distribution of the particles with the size ranging 5–7 nm. XRD Rietveld analysis confirms the formation of a pure and single Fe₃O₄ phase with high crystallinity. The ligands anchored on the magnetic nanoparticle surface have been confirmed by the shift of the characteristic Fe–O vibration band in the FT-IR spectrum, and have been supported by the stepwise weight loss in TGA as a function of temperature. The phosphorus content determined by ICP-MS is approximately 0.39 mmol of phosphine per gram of the nanoparticles. Magnetization-field curves recorded at room temperature reveal superparamagnetic behavior. MNP@bpd materials have proven to be excellent catalysts after in situ addition of the rhodium (Rh) metal precursor for the hydroformylation reaction of styrene and its derivatives. The extent of reusability of the catalyst has been tested and was found to be active even after seven consecutive cycles.