Transient Covalency in Molten Uranium(III) Chloride

• Published in: Journal of the American Chemical Society 2024-08, Vol.146 (31), p.21220-21224
• Main Authors: Maltsev, Dmitry S., Driscoll, Darren M., Zhang, Yuanpeng, Neuefeind, Joerg C., Reinhart, Benjamin, Agca, Can, Ray, Debmalya, Halstenberg, Phillip W., Aziziha, Mina, Schorne-Pinto, Juliano, Besmann, Theodore M., Bryantsev, Vyacheslav S., Dai, Sheng, Roy, Santanu, Ivanov, Alexander S.
• Format: Article
• Language: English
• Subjects: Ab Initio Molecular Dynamics; Actinides; Chemical Structure; Ions; RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; Raman Spectroscopy
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.4c05765

Uranium is arguably the most essential element in the actinide series, serving as a crucial component of nuclear fuels. While U is recognized for engaging the 5f orbitals in chemical bonds under normal conditions, little is known about its coordination chemistry and the nature of bonding interactions at extreme conditions of high temperature. Here we report experimental and computational evidence for the shrinkage of the average U–ligand distance in UCl3 upon the solid-to-molten phase transition, leading to the formation of a significant fraction of short, transient U–Cl bonds with the enhanced involvement of U 5f valence orbitals. These findings reveal that extreme temperatures create an unusual heterogeneous bonding environment around U­(III) with distinct inner- and outer-coordination subshells.