Ligand-Free Ultrasmall Recyclable Iridium(0) Nanoparticles for Regioselective Aromatic Hydrogenation of Phosphine Oxide Scaffolds: An Easy Access to New Phosphine Ligands.

Herein, we developed the recyclable ligand-free iridium (Ir)-hydride based Ir nanoparticles (NPs) for the first regioselective partial hydrogenation of P -substituted naphthalenes. Both the isolated and in situ generated NPs are catalytically active. A control nuclear magnetic resonance (NMR) study revealed the presence of metal-surface-bound hydrides, most likely formed from Ir species. A control NMR study confirmed that hexafluoroisopropanol as a solvent was accountable for substrate activation via hydrogen bonding. High-resolution transmission electron microscopy of the catalyst supports the formation of ultrasmall NPs, and X-ray photoelectron spectroscopy confirmed the dominance of Ir in the NPs. The catalytic activity of NPs is broad as showcased by highly regioselective aromatic ring reduction in various phosphine oxides or phosphonates. The study also showcased a novel pathway toward preparing bis(diphenylphosphino)-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl (H -BINAP) and its derivatives without losing enantioselectivity during catalytic events.