“Straining” to Separate the Rare Earths: How the Lanthanide Contraction Impacts Chelation by Diglycolamide Ligands

Ross J. Ellis, Derek M. Brigham, Laetitia Delmau, Alexander S. Ivanov, Neil J. Williams, Minh Nguyen Vo, Benjamin Reinhart, Bruce A. Moyer, Vyacheslav S. Bryantsev

Research output: Contribution to journalArticlepeer-review

81 Scopus citations

Abstract

The subtle energetic differences underpinning adjacent lanthanide discrimination are explored with diglycolamide ligands. Our approach converges liquid-liquid extraction experiments with solution-phase X-ray absorption spectroscopy (XAS) and density functional theory (DFT) simulations, spanning the lanthanide series. The homoleptic [(DGA)3Ln]3+ complex was confirmed in the organic extractive solution by XAS, and this was modeled using DFT. An interplay between steric strain and coordination energies apparently gives rise to a nonlinear trend in discriminatory lanthanide ion complexation across the series. Our results highlight the importance of optimizing chelate molecular geometry to account for both coordination interactions and strain energies when designing new ligands for efficient adjacent lanthanide separation for rare-earth refining.

Original languageEnglish
Pages (from-to)1152-1160
Number of pages9
JournalInorganic Chemistry
Volume56
Issue number3
DOIs
StatePublished - Feb 6 2017

Funding

This work was supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. M.N.V was supported through ASTRO2016 internship program at ORNL. This research used resources of the National Energy Research Scientific Computing Center supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231.

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