A Nuclear Magnetic Resonance Study on Ligand Exchange Reaction in U(VI) Nitrato Complex with n-Octyl(phenyl)-N, N-Diisobutylcarbamoylmethylphosphine Oxide in Acetone Containing Oxalic Acid
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In order to examine the effect of oxalic acid(H<SUB>2</SUB>ox) on the exchange reaction of n-octyl(phenyl)-N, N-diisobutylcarbamoylmethylphosphine oxide (oφcmpo) in U(VI) nitrato complex with oφcmpo, structural and kinetic studies have been carried out for the solutions prepared by dissolving UO<SUB>2</SUB>(NO<SUB>3</SUB>)<SUB>2</SUB>(oφcmpo), oφcmpo, and H<SUB>2</SUB>ox in CD<SUB>3</SUB>COCD<SUB>3</SUB> using <SUP>31</SUP>P and <SUP>13</SUP>C NMR method. The number of coordinated oφcmpo was determined to be 2 by the area integration of <SUP>31</SUP>P NMR signals of free and coordinated oφcmpo. From the area integration of <SUP>13</SUP>C signals of free H<SUB>2</SUB>ox and coordinated oxalate(Cox), the number of Cox was estimated to be 1. Hence, the complex with composition ratio of UO<SUP>2+</SUP><SUB>2</SUB>:oφcmpo: Cox=1:2:1 was supposed to be formed in the present solution system. The exchange rate of oφcmpo in this complex was found to show a first-order dependence on the free oφcmpo concentrations and to decrease with increasing free H<SUB>2</SUB>ox concentrations. From these results, it is proposed that the exchange reaction of oφcmpo proceeds through the interchange(I) mechanism and that the retardation effect of free H<SUB>2</SUB>ox is due to the formation of outer-sphere complex.
- Journal of Nuclear Science and Technology
Journal of Nuclear Science and Technology 34(12), 1133-1139, 1997-12-25
Atomic Energy Society of Japan