Actinide hexanuclear cluster [an6(oh)4(o)4(h2o)8]12+ (an = u(iv), np(iv), pu(iv)) structure, synthesis mechanism and physical-chemical properties - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2017

Actinide hexanuclear cluster [an6(oh)4(o)4(h2o)8]12+ (an = u(iv), np(iv), pu(iv)) structure, synthesis mechanism and physical-chemical properties

Résumé

Nanosized actinide oxide as well as hydroxide actinide clusters play an important role in the nuclear chemistry impacting the different industrial separation processes and the release and migration of actinide in the environment . Actinide(IV) are particularly involved because of their very low solubility and their ability to be easily hydrolyzed. The competition between hydrolysis and complexation is likely to lead to the formation of soluble polynuclear species that could largely influence the chemistry . Significant discrepancies in thermodynamic data exist between different studies and/or reality due to oversimplified and incorrected chemical models. Even if the presence of such soluble oligomeric species is now well-established, they are largely absent in thermodynamic descriptions of aqueous speciation because of a lack of thermodynamic data. Herein we report the structure of new actinide(IV) hexanuclear core species [An6(OH)4O4]12+ (An = U, Np, Pu), [An6(OH)4O4(H2O)8(HDOTA)4].HNO3.nH2O. The cluster is stabilized with a polyamino carboxylic acid, DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), which is an hydrophilic ligand considered in separation processes and in actinide interaction with human body. In addition to the crystalographic description obtained thanks to single crystal XRD, EXAFS investigations combined with UV-vis spectroscopy were carried out and evidenced the same local structure in moderate acidic and neutral solutions. The synthesis mechanism was partially elucidated and the cluster main physical chemical properties (pH range stability, solubility, synthesis mechanism and protonation constant) were determined highlighting the importance of these polynuclear species consideration in thermodynamic models.
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Dates et versions

hal-02419641 , version 1 (19-12-2019)

Identifiants

  • HAL Id : hal-02419641 , version 1

Citer

C. Tamain, T. Dumas, D. Guillaumont, P. Guilbaud, C. Hennig. Actinide hexanuclear cluster [an6(oh)4(o)4(h2o)8]12+ (an = u(iv), np(iv), pu(iv)) structure, synthesis mechanism and physical-chemical properties. actinides 2017, Jul 2017, Sendai, Japan. ⟨hal-02419641⟩

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