Identification of hexanuclear Actinide(IV) carboxylates with Thorium, Uranium and Neptunium by EXAFS spectroscopy
Identification of hexanuclear Actinide(IV) carboxylates with Thorium, Uranium and Neptunium by EXAFS spectroscopy
Hennig, C.; Takao, S.; Takao, K.; Weiss, S.; Kraus, W.; Emmerling, F.; Meyer, M.; Scheinost, A. C.
Hydrated actinide(IV) ions undergo hydrolysis and further polymerization and precipitation with increasing pH. The resulting amorphous and partly crystalline oxydydroxides AnOn(OH)4−2nxH2O can usually be observed as colloids above the An(IV) solubility limit. The aging process of such colloids results in crystalline AnO2. The presence of carboxylates in the solution prevents the occurrence of such colloids by formation of polynuclear complexes through a competing reaction between hydrolysis and ligation. The majority of recently described carboxylates reveals a hexanuclear core of [An6(μ3-O)4(μ3-OH)4]12+ terminated by 12 carboxylate ligands. We found that the An(IV) carboxylate solution species remain often preserved in crystalline state. The An(IV) carboxylates show An-An distances which are ~ 0.03 Å shorter than the An-An distances in AnO2 like colloids. The difference in the distances could be used to identify such species in solution.
Keywords: EXAFS; Actinides; Carboxylates
Involved research facilities
- Rossendorf Beamline at ESRF DOI: 10.1107/S1600577520014265
Related publications
- DOI: 10.1107/S1600577520014265 is cited by this (Id 17660) publication
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Journal of Physics: Conference Series 430(2013), 012116
DOI: 10.1088/1742-6596/430/1/012116
Cited 15 times in Scopus
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