Phosphoryl-Ligand Adducts of Rare Earth-TriNOx Complexes: Systematic Studies and Implications for Separations Chemistry

Phosphoryl ligands of the general formula OPR3 (R = Me, OMe, Et, nBu, Ph, iPr, NMe2) were coordinated to [Nd­(TriNOx)] (TriNOx3– = ([(2-tBuNO)­C6H4CH2]3N)3–), and the resulting complexes were characterized. Solution equilibrium constants for each complex were determined, demonstrating a large range for phosphoryl ligands’ Lewis basicity. Thermogravimetric analyses provided evidence for the qualitative thermodynamic preference of phosphoryl ligands for [Nd­(TriNOx)] over the dysprosium analogue. These findings were exploited for the separation of binary mixtures of neodymium/dysprosium and lanthanum/neodymium. Implementation of phosphoryl ligands in the TriNOx separation system expands its scope and demonstrates a fundamentally different mode for separating rare-earth cations based on adducts with neutral donors.