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NMR AND IR SPECTROMETRY STUDIES OF MONOAMIDE COMPLEXES WITH PLUTONIUM(IV) AND LANTHANIDE(III) NITRATES.

1995; Taylor & Francis; Volume: 13; Issue: 5 Linguagem: Inglês

10.1080/07366299508918303

1532-2262

Claude Berthon, C. Chachaty,

Chemical Synthesis and Characterization

ABSTRACT Monoamide (E) extractants are potential candidates to replace the tri-n-butyl phosphate (TBP) used in the reprocessing of nuclear fuels. In the present study, we essentially used NMR (13C and 1H) spectroscopy to identify the kinds of structural parameters conditioning the selectivity and efficiency of monoamide extractants. Information on nitrate groups bonded to the metallic ions and to the carbonyl moiety of monoamides was obtained by IR spectroscopy. The symmetric monoamides used in this study were : DEHBA=C3H7CON(CH2CH(C2H5)C4H9)2, DEHiBA=(CH3)2CHCON(CH2CH(C2Hs)C4H9)2and DEHDMBA=(CH3)3CCH2CON(CH2CH(C2Hs)C4H9)2 Complexation between lanthanide(III) nitrates (E) and monoamides (E) yields the stoichiometrics E:Ln = 2:1 and 3:1. The ability to form 3:1 complexes depends on the steric hindrance on the carbonyl moiety, the metal ionic radius, and the presence of nitrate ions in the first coordination sphere of the metal ion. The same feature is observed for monoamide complexes of Pu(NO3)4 and Th(NO3)4. A structural analysis was undertaken with complexes. Fast exchange rates were found between the monoamide ligand and the complexes. The structural data obtained by NMR spectroscopy on these complexes help to explain the different affinities (low for Ln(III) and high for Pu(IV)) exhibited by these metallic nitrates towards extraction by monoamide ligands.