Phosphine Ligand-Free Bimetallic Ni(0)Pd(0) Nanoparticles as a Catalyst for Facile, General, Sustainable, and Highly Selective 1,4-Reductions in Aqueous Micelles

Phosphine ligand-free bimetallic nanoparticles (NPs) composed of Ni(0)Pd(0) catalyze highly selective 1,4-reductions of enones, enamides, enenitriles, and ketoamides under aqueous micellar conditions. A minimal amount of Pd (Ni/Pd = 25:1) is needed to prepare these NPs, which results in reductions without impacting N- and O-benzyl, aldehyde, nitrile, and nitro functional groups. A broad range of substrates has been studied, including a gram-scale reaction. The metal–micelle binding is supported by surface-enhanced Raman spectroscopy data on both the NPs and their individual components. Optical imaging, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy analyses reveal the formation of NP-containing micelles or vesicles, NP morphology, particle size distribution, and chemical composition. X-ray photoelectron spectroscopy measurements indicate the oxidation state of each metal within these bimetallic NPs.