N,N,N’,N’-tetraoctyldiglycolamide (TODGA) and N,N,N’,N’-tetrahexyldiglycolamide (THDGA) were synthesized and characterized in order to further evaluate them as extracting agents for Eu(III) and Co(II) from nitric and hydrochloric acid solutions. Analysis of the dependence of metal distribution ratio, D_M, on concentrations of reagents indicated that the dominant extracted complexes are Eu(TODGA)₃(NO₃)₃(HNO₃), Eu(THDGA)₃(NO₃)₃(HNO₃), Eu(THDGA)₃(NO₃)₃(HNO₃)₂ and Co(TODGA)Cl₂(HCl). In addition, TODGA was evaluated for partitioning of Eu(III). It was concluded that, with acidity adjustment, Eu(III) can be separated from Zr(IV), Nb(V), Co(II) and Cs(I) in nitric and hydrochloric acids.

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Adsorption behavior of the group-5 elements, ⁹⁵Nb and ¹⁷⁹Ta, on cation-exchange resin was studied in mixed solution of HF and HNO₃ (HF/HNO₃) as a model experiment of their heavier homologue, element 105 (dubnium, Db). Chemical reactions of these elements in the cation exchange rapidly reached the equilibrium. It was found that distribution coefficients of Nb and Ta decrease with increasing the fluoride ion concentration in the studied range of 10⁻⁷–10⁻⁵ M. Clear difference between Nb and Ta was observed in the variations of the distribution coefficients against the fluoride ion concentration. This would originate from their different chemical species of fluoride complexes. We propose the cation-exchange experiment of Db based on the present experimental results to understand its fluoride complex formation.

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A novel mixed-valence trinuclear heterometal pentafluorobenzoate cluster complex Cr³⁺Fe³⁺Fe²⁺O(C₆F₅COO)₆(C₅H₅N)₃·0.5C₅H₅N·CH₂Cl₂ was synthesized, and its ⁵⁷Fe-Mössbauer spectra were measured with a temperature range of 78 to 298 K. It has been revealed that just one apparent valence state of Fe^2.5+ was observed at room temperature.

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