sup 31 P NMR study of the complexation of TBP with lanthanides and actinides in solution and in a clay matrix

摘要

Goal was to use NMR to study TBP/lanthanide complexes in the interlayer or on edge sites of clays. Work in this laboratory yielded details of the complexation of Eu(NO(sub 3))(sub 3) and Pr(NO(sub 3))(sub 3) with TBP in hexane solution; this information is crucial to interpretation of results of NMR studies of the complexes exchanged into clays. The solution (sup 31)P-chemical shift values were improved by repeating the studies on the lanthanide salts dissolved directly into neat TBP. NMR studies of these neat solutions of the Eu(NO(sub 3))(sub 3)(lg bullet)3TBP-complex and the Pr(NO(sub 3))(sub 3)(lg bullet)3TBP-complex show that the (sup 31)P chemical shift remains relatively constant for TBP: lanthanide ratios below 3: 1. At higher ratios, the chemical shift approaches that of free TBP, indicating rapid exchange of TBP between the free and complexed state. Exchange of these complexes into the clay hectorite yielded discrete (sup 31)P-NMR signals for the Eu(lg bullet)TBP complex at -190 ppm and free TBP at -6 ppm. Adsorption of the Pr(lg bullet)TBP complex yielded broad signals at 76 ppm for the complex and -6 ppm for free TBP. There was no evidence of exchange between the incorporated complex and the free TBP.