Determination of Uranium Central-Field Covalency with 3 <i>d</i> 4 <i>f</i> Resonant Inelastic X-ray Scattering
Timothy G. Burrow, Nathan M. Alcock, Myron S. Huzan, Maja A. Dunstan, John A. Seed, Blanka Detlefs, Pieter Glatzel, Myrtille O. J. Y. Hunault, Jesper Bendix, Kasper S. Pedersen, Michael L. Baker
Abstract
High Resolution Image Download MS PowerPoint Slide Understanding the nature of metal–ligand bonding is a major challenge in actinide chemistry. We present a new experimental strategy for addressing this challenge using actinide 3 d 4 f resonant inelastic X-ray scattering (RIXS). Through a systematic study of uranium(IV) halide complexes, [UX 6 ] 2–, where X = F, Cl, or Br, we identify RIXS spectral satellites with relative energies and intensities that relate to the extent of uranium-ligand bond covalency. By analyzing the spectra in combination with ligand field density functional theory we find that the sensitivity of the satellites to the nature of metal–ligand bonding is due to the reduction of 5 f interelectron repulsion and 4 f -5 f spin-exchange, caused by metal–ligand orbital mixing and the degree of 5 f radial expansion, known as central-field covalency. Thus, this study furthers electronic structure quantification that can be obtained from 3 d 4 f RIXS, demonstrating it as a technique for estimating actinide-ligand covalency.