Preparation of N,N-Dialkylcarbamato Lanthanide Complexes by Extraction of Lanthanide Ions from Aqueous Solution into Hydrocarbons

Lanthanides are easily extracted as N,N-dibutylcarbamato complexes from aqueous solutions of their chlorides into heptane solutions of dibutylamine saturated with CO2. The products are recovered in high yields and are soluble in hydrocarbons. The derivatives [Ln(O2CNBu2)(3)] [Ln = Nd (1), Eu (2), Tb (3)] [NH2Bu2](2)[Ln(4)(CO3)-(O2CNBu2)(12)] [Ln = Tb (4), Sm (5), Eu (6)] and [Sm-4(CO3)(O2CNBu2)(10)], 7, have thus been obtained. The crystal and molecular structure of 4 has been solved; the samarium and europium complexes 5 and 6 were found to be isostructural. Mass spectra of the complexes 1-3, 4, and 7 (in MeCN/toluene) reveal that equilibria are present in solution. Compound 2 has been reacted in toluene with NHBz(2) in the presence of CO2 affording [NH(2)Bz(2)][Eu(O(2)CNBz(2))(4)], 8, through a ligand exchange process. By thermal treatment, 8 afforded [Eu(O(2)CNBz(2))(3)](n), 9. With a similar procedure [Sm(O(2)CNBz(2))(3)](n), 10, was obtained from 5. According to the photoluminescence study carried out on solid samples of 2, 4, 5, 7, and 8, the metal centered f-f transitions represent the only effective way to induce lanthanide luminescence in these complexes.