Chiral anion-based NMR enantiodiscrimination of a dinuclear, cationic Ir(i) NHC complex with a figure-of-eight loop structure

Abstract

A dinuclear Ir(I) complex with a bis-NHC ligand was formed in situ from 1,1′-((4,6-dimethyl-1,3-phenylene)bis(methylene))bis(3-methyl-1H-imidazol-3-ium) in the presence of Cs₂CO₃ and [Ir(μ-Cl)(cod)]₂. Its solid-state structure, determined by X-ray diffraction, shows a figure-of-eight loop with both the P and M enantiomers being present. Solution NMR studies were performed to examine the enantiodiscrimination between them by applying the enantiopure anions tris(tetrachlorobenzenediolato)phosphate(V) (Δ-TRISPHAT) and bis(tetrachlorobenzenediolato)mono([1,10]binaphthalenyl-2,20-diolato)phosphate(V) (Λ-BINPHAT).