Coordination of Tetravalent Actinides (An=Th IV , U IV , Np IV , Pu IV ) with DOTA: From Dimers to Hexamers - CEA - Commissariat à l’énergie atomique et aux énergies alternatives
Article Dans Une Revue Chemistry - A European Journal Année : 2017

Coordination of Tetravalent Actinides (An=Th IV , U IV , Np IV , Pu IV ) with DOTA: From Dimers to Hexamers

Résumé

Abstract Three tetravalent actinide (An IV ) hexanuclear clusters with the octahedral core [An 6 (OH) 4 O 4 ] 12+ (An IV =U IV , Np IV , Pu IV ) were structurally characterized in the solid state and in aqueous solution by using single‐crystal X‐ray diffraction, X‐ray absorption, IR, Raman, and UV/Vis spectroscopy. The observed structure, [An 6 (OH) 4 O 4 (H 2 O) 8 (HDOTA) 4 ] ⋅ HCl/HNO 3 ⋅ n H 2 O (An=U( I ), Np( II ), Pu( III )), consists of a An IV hexanuclear pseudo‐octahedral cluster stabilized by DOTA (1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid) ligands. The six actinide atoms are connected through alternate μ 3 ‐O 2− and μ 3 ‐OH − groups. Extended X‐ray absorption fine structure (EXAFS) investigations combined with UV/Vis spectroscopy provide evidence for the same local structure in moderate acidic and neutral aqueous solutions. The synthesis mechanism was partially elucidated and the main physicochemical properties (pH range stability, solubility, and protonation constant) of the cluster were determined. The results underline the importance of: 1) considering such polynuclear species in thermodynamic models, and 2) competing reactions between hydrolysis and complexation. It is interesting to note that the same synthesis route with thorium(IV) led to the formation of a dimer, Th 2 (H 2 O) 10 (H 2 DOTA) 2 ⋅ 4 NO 3 ⋅ x H 2 O ( IV ), which contrasts to the structure of the other An IV hexamers.
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Dates et versions

cea-04695901 , version 1 (12-09-2024)

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Citer

Christelle Tamain, Christoph Hennig, Philippe Guilbaud, Thomas Dumas. Coordination of Tetravalent Actinides (An=Th IV , U IV , Np IV , Pu IV ) with DOTA: From Dimers to Hexamers. Chemistry - A European Journal, 2017, 23 (28), pp.6864-6875. ⟨10.1002/chem.201700493⟩. ⟨cea-04695901⟩
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