NMR STUDY OF LANTHANIDE(III) NITRATE-CMPO EXTRACTION SYSTEM (I) STRUCTURE OF EXTRACTEDCHEMICAL SPECIES

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Abstract
Octyl(phenyl)-N,N-dtisobutylcarbamoylmethylphosphine oxide used in the TRUEX process is a new extractant for TRU elements. NMR measurements were carried out to study the coordination structure of lanthanide(III)-CMPO complexes. By analyzing Lan- thanide-Induced-Shifts(LIS) data It was found that CMPO molecule locates in the equatorial region with respect to the principal magnetic Z axis. From the NMR longitudinal relaxation time measurements for Ce(N03)3· 3CMPO, the distance of Ce3+-P, Ce3+- C(bridging methylene carbon) and Ce3+-C(carbonyl carbon) were estimated to be 3.3, 3.1 and 3.1 Å, respectively, suggesting that CMPO coordinates to the central Ce3+ ion in a bidentate manner with the phosphoryl and carbonyl groups. This is consistent with the low frequency shifts of phosphoryl and carbonyl stretching frequencies observed in the IR spectrum of Ce(N03)3·3CMPO. Moreover, from the dependence of 31P-NMR spectra for Nd(N03)3·3CMPO and Er(N03)3·2CMPO on temperature, lanthanide(IH) -CMPO complexes exist as several isomers in CDC13 and a rapid intramolecular interconversion occurs at higher temperature region.