An Operationally Simple Method for Separating the Rare‐Earth Elements Neodymium and Dysprosium

Abstract Rare‐earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare‐earth metal salts. Metal complexes of a tripodal nitroxide ligand (2‐ t BuNO) C 6 H 4 CH 2 3 N 3− (TriNOx 3−), feature a size‐sensitive aperture formed of its three η 2 ‐ (N, O) ligand arms. Exposure of metal cations in the aperture induces a self‐associative equilibrium comprising M (TriNOx) thf/ M (TriNOx) 2 (M=rare‐earth metal). Differences in the equilibrium constants (K eq) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio S Nd/Dy =359.