Accessing Long-Lived, Highly Stable Phosphine-Ligand-Free Palladium Hydrides via Palladium-Micelle Synergy

Palladium hydrides (PdH_x) are significant to hydrogen-transfer chemistry, yet their prolonged aqueous and air instability as well as their reliance on strong ligands for stabilization have limited their practical applications. Herein, we report dynamic micelle-enabled stable PdH_x nanoparticles that are readily generated and suspended within nonionic micelles. This synthesis process employs Pd(OAc)₂ as the Pd precursor, MeMgBr as the reductant, amphiphile PS-750-M as shielding nonionic micelles, and water as the dispersion medium. These hydride-rich nanophases persist for more than 1 year in air-saturated moisture, overcoming the canonical fragility of such metal hydrides in protic media. The micellar architecture provides hydrophobic compartments that shield PdH_x from proton-induced decomposition while maintaining access to H₂ and substrate for catalysis. These hydrides were found to be basic in nature, as evidenced by external base-free catalytic detriflation, a transformation otherwise known to generate triflic acid in situ. Pd K-edge X-ray absorption and ¹H nuclear magnetic resonance spectroscopy confirm the presence of persistent PdH_x species. The long-term stability and catalytic activity of these PdH_x@micelles are significant for materials chemistry and catalysis.