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Updated: Jan 12, 2026
Speciation and Bioavailability Measurements of Environmental Plutonium Using Diffusion in Thin Films
Published on: November 9, 2015
Structural and Spectroscopic Characterization of Plutonium and Other Tetravalent Metals Complexed to a Keggin Ion
Jenna Bustos1,2, Ian Colliard2, Vitalie Stavila3
1Oregon State University, Corvallis, Oregon 97331, United States.
Abstract:
We report the isolation of the first plutonium(IV) complex with a Keggin ion chelator: Cs20[Pu(PW11O39)2]2·13H2O. Single crystal XRD and solid-state UV-vis absorbance analysis demonstrate the stabilization of Pu4+ by the Keggin ligand. The unit cell contains two [Pu(PW11O39)2]10- complexes (Pu(PW11)2) bridged by Cs+. Raman and 31P NMR spectra of Pu(PW11)2 are consistent with the analogous Zr4+, Hf4+, Ce4+, and Th4+ complexes. The Pu-O bond distances at the two Pu sites are 2.35(3) and 2.34(3) Å, matching the value extrapolated from the bonding trend built with the other 8-coordinated tetravalent cations. However, the long-range arrangement of the Pu(PW11)2 complexes within the lattice is unique in the series of MIV(PW11)2 compounds: pairs of Pu(PW11)2 are organized perpendicular to each other. Based on solution-state UV-visible absorbance, small-angle X-ray scattering (SAXS), and 31P NMR, the tetravalent cations quantitatively form the 1:2 species in solution ([Pu(PW11O39)2]10-(aq)) and no 1:1 species ([Pu(PW11O39)(H2O)x]3-(aq)). Finally, a linear correlation exists between the metal-oxygen distances in the MIV(PW11)2 compounds and the corresponding metal dioxides, allowing for extrapolation for Pa4+, Am4+, and Bk4+. The results indicate that our microscale POM approach represents a viable pathway to probe properties of rare actinide ions in discrete molecules, beyond the traditional oxide extended solids.
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