Paramagnetism of Aqueous Actinide Cations. Part I: Perchloric Acid Media

• Published in: Inorganic chemistry Vol. 53; no. 5; pp. 2450 - 2459
• Main Authors: Wall, Thomas F, Jan, Steve, Autillo, Matthieu, Nash, Kenneth L, Guerin, Laetitia, Naour, Claire Le, Moisy, Philippe, Berthon, Claude
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 03-03-2014
• Subjects: Chemical Physics; Physics
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic402371x

A comprehensive study of actinide cation paramagnetism in acidic aqueous solution has been completed in perchlorate media. Employing the Evans method, all the readily accessible actinide cations have been studied using our specially outfitted NMR spectrometer equipped for use with radioactive samples. The effective magnetic moments observed, ranging from 0 to 13 μB, differ from the isoelectronic lanthanides, previous solid actinide studies, and older solution studies. Actinide (IV) and (V) ions show less paramagnetic character, while some actinide (III) ions exhibit greater paramagnetic behavior than predicted from free-ion calculation. Temperature dependence of actinide magnetic susceptibilities from 5 to 80 °C are in good agreement with a Curie-like law except for U(VI), which appears to be temperature-independent. Diamagnetic behavior of Th(IV) exhibits a very low temperature dependence of the magnetic susceptibility. Some explanations for the observations are offered, and the 5f electron behavior is compared to the 4f analogues.