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Polynuclear Complexes of Nd and Dy with N 2 O 3 Donor Ligands: Solution Speciation and Selective Precipitation Studies

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide This study explores the formation and selective separation of polynuclear neodymium and dysprosium complexes with N 2 O 3 donor ligands derived from N, N -bis(salicylidene)-1,3-diamino-2-propanol (H 3 L H ). The research focuses on the structural characterization and solution speciation of Nd 3+ and Dy 3+ complexes by using ligands with different peripheral substituents: H 3 L H, H 3 L p-OMe, and H 3 L o-tBu . These substituents significantly influence the nuclearity of the resulting complexes. For Dy 3+, single-crystal X-ray diffraction (SC-XRD) revealed a range of molecular architectures, from dinuclear to hexanuclear species, each with distinct solubility profiles, whereas for Nd 3+ an heptanuclear molecular structure with H 3 L o-tBu was obtained. Separation experiments with Nd:Dy ratios of 1:1 and 4:1 demonstrated the ability of the ligands to give a partial selective precipitation of Nd 3+ and Dy 3+ complexes, depending on both metal identity and ligand structure. In particular, H 3 L H achieved a separation factor ( S Nd/Dy ) of 12.0 (±2.0), concentrating Nd 3+ in the solid phase. In contrast, H 3 L o-tBu favored Dy precipitation, yielding a separation factor of 20.0 (±4) after just 10 min. In various instances, the low separation factor values were ascribed to the formation of mixed-metal polynuclear species, which was confirmed through Electrospray Ionization Mass Spectrometry (ESI-MS) and by the structural characterization of a heteronuclear complex with H 3 L o-tBu .

Source: Inorganic Chemistry

DOI: 10.1021/acs.inorgchem.5c03477