A Nuclear Magnetic Resonance Study on Ligand Exchange Reactions in U (VI) Nitrato Complexes with Ligands Containing Phosphoryl Group in Non-aqueous Solvents

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The exchange reactions of tributyl phosphate (TBP) and dihexyl-N, N-diethylcarbamoylmethylphosphonate (CMP) in U(VI) nitrato complexes with TBP or CMP (abbreviated as U(VI)-TBP or U(VI)-CMP) have been studied by means of <SUP>31</SUP>P NMR method in CD<SUB>3</SUB>COCD<SUB>3</SUB> or CD<SUB>2</SUB>Cl<SUB>2</SUB>. The number of TBP coordinated to uranyl nitrate was directly determined to be 1 in CD<SUB>3</SUB>COCD<SUB>3</SUB> and 2 in CD<SUB>2</SUB>Cl<SUB>2</SUB> by the area integrations of <SUP>31</SUP>P NMR signals of free and coordinated TBP. Similarly, the number of coordinated CMP was evaluated as 1 in CD<SUB>3</SUB>COCD<SUB>3</SUB>. The exchange rate constants of TBP and CMP in U(VI)-TBP and U(VI)-CMP complexes were calculated by the two-site exchange model. The exchange rate of TBP in U(VI)-TBP is independent of the free TBP concentrations ([TBP]<SUB>f</SUB> ), while that in U(VI)-CMP is dependent on [CMP]<SUB>f</SUB>. From these results, the dissociative (D) and interchange (I) mechanisms were proposed for the exchange reactions of TBP in U(VI)-TBP and CMP in U(VI)-CMP, respectively. Kinetic parameters are as follows: rate constant (25°C), ΔH<SUP>≠</SUP>(kJ-mol<SUP>-1</SUP>), ΔS<SUP>≠</SUP>(J•K<SUP>-1</SUP>•mol<SUP>-1</SUP>); 9.9×10<SUP>3</SUP>s<SUP>-1</SUP>, 33.7, -55.4 (U(VI)-TBP system), 2.3×10<SUP>4</SUP> m<SUP>-1</SUP>•s<SUP>-</SUP>1 (apparent second-order), 25.2, -75.9 (U(VI)-CMP system).

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  • Journal of nuclear science and technology  

    Journal of nuclear science and technology 34(3), 298-303, 1997-03-25 

    Atomic Energy Society of Japan

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各種コード

  • NII論文ID(NAID)
    10002076743
  • NII書誌ID(NCID)
    AA00703720
  • 本文言語コード
    ENG
  • 資料種別
    ART
  • ISSN
    00223131
  • NDL 記事登録ID
    4176283
  • NDL 雑誌分類
    ZM35(科学技術--物理学)
  • NDL 請求記号
    Z53-A460
  • データ提供元
    CJP書誌  NDL  J-STAGE 
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