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Uranyl peroxide nanoclusters are an evolving family of materials with potential applications throughout the nuclear fuel cycle. While several studies have investigated their interactions with alkali and alkaline earth metals, no studies have probed their interactions with the actinide elements. This work describes a system containing U60Ox30, [((UO2)(O2))60(C2O4)30]60−, and neptunium(V) as a function of neptunium concentration. Ultra‐small and small angle X‐ray scattering were used to observe these interactions in the aqueous phase, and X‐ray diffraction was used to observe solid products. The results show that neptunium induces aggregation of U60Ox30 when the neptunium concentration is≤10 mM, whereas (NpO2)2C2O4 ⋅ 6H2O(cr) and studtite ultimately form at 15–25 mM neptunium. The latter result suggests that neptunium coordinates with the bridging oxalate ligands in U60Ox30, leaving metastable uranyl peroxide species in solution. This is an important finding given the potential application of uranyl peroxide nanoclusters in the recycling of used nuclear fuel. [ABSTRACT FROM AUTHOR]

Uranyl peroxide nanoclusters are an evolving family of materials with potential applications throughout the nuclear fuel cycle. While several studies have investigated their interactions with alkali and alkaline earth metals, no studies have probed their interactions with the actinide elements. This work describes a system containing U60Ox30, [((UO2)(O2))60(C2O4)30]60−, and neptunium(V) as a function of neptunium concentration. Ultra‐small and small angle X‐ray scattering were used to observe these interactions in the aqueous phase, and X‐ray diffraction was used to observe solid products. The results show that neptunium induces aggregation of U60Ox30 when the neptunium concentration is≤10 mM, whereas (NpO2)2C2O4 ⋅ 6H2O(cr) and studtite ultimately form at 15–25 mM neptunium. The latter result suggests that neptunium coordinates with the bridging oxalate ligands in U60Ox30, leaving metastable uranyl peroxide species in solution. This is an important finding given the potential application of uranyl peroxide nanoclusters in the recycling of used nuclear fuel. [ABSTRACT FROM AUTHOR]

The assembly of molybdenum polyoxometalates (POMs) has afforded large discrete nanoclusters with varied degrees of reduction such as the ~20 % reduced molybdenum blues. While many heterometals have been incorporated into these clusters to afford new properties, uranium has yet to be reported. Here we report the first uranium containing molybdenum blue clusters and the unique properties exhibited by this incorporation. The uranyl ion (UO 2 2+ ) directs formation of Mo 72 U 8 , a square POM comprised of two faces connected by eight edge-sharing molybdenum dimers. Mo 72 U 8 , a chiral cluster, crystallizes as a racemic mixture and, in the solid state, has a 'negative' charge localized on one face of the cluster opposite the 'positively' charged face of another cluster. Using U(IV) as both heterometal and molybdenum reductant afforded crystals of Mo 97 U 10 , a wheel cluster with a heptamolybdate cap on one face. Mo 97 U 10 dissociates in solution, losing the heptamolybdate, to form Mo 90 U 10 . Using more solvent during synthesis afforded crystals of Mo 90 U 10 S 4 which, instead of heptamolybdate, contains four sulfate ions. Crystals of Mo 90 U 10 S 4 undergo a dehydration induced phase change where clusters form a sheet through oxide bridges. Half of the bridges are cation-cation interactions between the uranyl oxygen atom and molybdenum, the first reported of this kind., (© 2024 Wiley-VCH GmbH.)

Uranyl peroxide nanoclusters are an evolving family of materials with potential applications throughout the nuclear fuel cycle. While several studies have investigated their interactions with alkali and alkaline earth metals, no studies have probed their interactions with the actinide elements. This work describes a system containing U 60 Ox 30 , [((UO 2 )(O 2 )) 60 (C 2 O 4 ) 30 ] 60- , and neptunium(V) as a function of neptunium concentration. Ultra-small and small angle X-ray scattering were used to observe these interactions in the aqueous phase, and X-ray diffraction was used to observe solid products. The results show that neptunium induces aggregation of U 60 Ox 30 when the neptunium concentration is≤10 mM, whereas (NpO 2 ) 2 C 2 O 4  ⋅ 6H 2 O(cr) and studtite ultimately form at 15-25 mM neptunium. The latter result suggests that neptunium coordinates with the bridging oxalate ligands in U 60 Ox 30 , leaving metastable uranyl peroxide species in solution. This is an important finding given the potential application of uranyl peroxide nanoclusters in the recycling of used nuclear fuel., (© 2023 Wiley-VCH GmbH.)