Ab Initio Study of Covalency in the Ground versus Core-Excited States and X-ray Absorption Spectra of Actinide Complexes

Dumitru-Claudiu Sergentu; Thomas J Duignan; Jochen Autschbach

doi:10.1021/acs.jpclett.8b02412

Ab Initio Study of Covalency in the Ground versus Core-Excited States and X-ray Absorption Spectra of Actinide Complexes

J Phys Chem Lett. 2018 Sep 20;9(18):5583-5591. doi: 10.1021/acs.jpclett.8b02412. Epub 2018 Sep 12.

Authors

Dumitru-Claudiu Sergentu¹, Thomas J Duignan¹, Jochen Autschbach¹

Affiliation

¹ Department of Chemistry , University at Buffalo, The State University of New York , Buffalo , New York 14260-3000 , United States.

PMID: 30180572
DOI: 10.1021/acs.jpclett.8b02412

Abstract

Relativistic multireference ab initio wave function calculations within the restricted active space (RAS) framework were performed to calculate metal and ligand X-ray absorption (XAS) near-edge spectroscopy (XANES) intensities for the metal M_4,5 edges of [PuO₂(H₂O)₅]²⁺, [An^VIO₂]²⁺ (An = U, Np, Pu), and [AmCl₆]^3- and the Cl K edge of the Am complex. The extent of An(5f)-ligand bonding was determined via natural localized molecular orbital analyses of the relevant spin-orbit coupled multireference states. The calculated spectra are in good agreement with experiments and allow a detailed assignment of the observed spectral features. The XANES M_4,5-edge spectra are representative of the actinide orbital covalency in the probed core-excited states, which may be different from the ground-state covalency. An assignment of ground-state An orbital covalency based on XAS spectra should therefore be made with caution.