Comparative investigation of N donor ligand-lanthanide complexes from the metal and ligand point of view

• Published in: Journal of Physics: Conference Series
• Main Authors: Pruessmann, T., Denecke, M. A., Geist, A., Rothe, J., Lindqvist-Reis, P., Loeble, M., Breher, F., Batchelor, D. R., Apostolidis, C., Walter, O., Caliebe, W., Kvashnina, K., Jorissen, K., Kas, J. J., Rehr, J. J., Vitova, T.
• Other Authors: Karlsruhe Inst Technol, POB 3640, D-76021 Karlsruhe, Germany, JRC Institute for Transuranium Elements Karlsruhe (ITU ), European Commission - Joint Research Centre Karlsruhe (JRC), HASYLAB, D-22603 Hamburg, Germany, European Synchrotron Radiation Facility (ESRF), Univ Washington, Dept Phys, Seattle, WA 98195 USA
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2012
• Subjects: [PHYS]Physics [physics]; Orca
• Online Access: https://hal.archives-ouvertes.fr/hal-01572871; https://hal.archives-ouvertes.fr/hal-01572871/document; https://hal.archives-ouvertes.fr/hal-01572871/file/J_Phys_Conf_Series_430_012115.pdf; https://doi.org/10.1088/1742-6596/430/1/012115

International audience N-donor ligands such as n-Pr-BTP (2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine) studied here preferentially bind An(III) over Ln(III) in liquid-liquid separation of trivalent ac-tinides from spent nuclear fuel. The chemical and physical processes responsible for this selectivity are not yet well understood. We present systematic comparative near-edge X-ray absorption structure (XANES) spectroscopy investigations at the Gd L-3 edge of [GdBTP3](NO3)(3), [Gd(BTP)(3)](OTf)(3), Gd(NO3)(3), Gd(OTf)(3) and N K edge of [Gd(BTP)(3)](NO3)(3), Gd(NO3)(3) complexes. The pre-edge absorption resonance in Gd L3 edge high-energy resolution X-ray absorption near edge structure spectra (HR-XANES) is explained as arising from 2p(3/2) -> 4f/5d electronic transitions by calculations with the FEFF9.5 code. Experimental evidence is found for higher electronic density on Gd in [Gd(BTP)(3)](NO3)(3) and [Gd(BTP)(3)](OTf)(3) compared to Gd in Gd(NO3)(3) and Gd(OTf)(3), and on N in [Gd(BTP)(3)](NO3)(3) compared to n-Pr-BTP. The origin of the pre-edge structure in the N K edge XANES is explained by density functional theory (DFT) with the ORCA code. Results at the N K edge suggest a change in ligand orbital occupancies and mixing upon complexation but further work is necessary to interpret observed spectral variations