Valence Delocalization in Trithorium Clusters Identified via Valence-to-Core Resonant Inelastic X-ray Scattering
Year: 2026
Type: preprint
Abstract: L 3 -edge valence-to-core resonant inelastic X-ray scattering (V2C-RIXS) is applied to thorium for the first time, demonstrating the technique’s sensitivity to actinide 6d-orbital participation in bonding. This sensitivity is exploited to identify states arising from delocalized valence molecular orbitals of predominantly 6d character in two trithorium clusters, [{Th(η 8 -C 8 H 8 )(µ 3 -Cl) 2 } 3 {K(DME) 2 } 2 ] 2b and [K(2.2.2-cryptand)] [{Th(η 8 -C 8 H 8 )(µ 3 -Cl) 2 } 3 ] 3 . Density functional theory based restricted open-shell configuration interaction with singles (DFT/ROCIS) accurately reproduces the V2C-RIXS spectra of 2b and 3 , enabling the quantitative assignment of inelastic intensity to the population of a delocalized three-center 6d z2 σ-bonding molecular orbital. In contrast, L 3 -edge high-energy-resolution fluorescence detection (HERFD) XANES spectra exhibit negligible sensitivity to 6d electron population in these compounds. This study, thus, establishes a clear distinction between the two techniques and identifies V2C-RIXS as a unique probe of 6d orbital contributions to bonding in actinide compounds.
Source: ChemRxiv
Institutions: University of Manchester, Research Complex at Harwell
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: Diamond Light Source
OpenAlex ID: W7207763288