SYNTHESIS AND CHARACTERIZATION OF LANTHANIDE S-(-)-2-PYRROLIDONE-5-CARBOXYLATES (PCA)

Salts with composition Ln(PCA)(3) . 2H(2)O (Ln=La, Pr, Nd, Sm, Eu and Tb) were obtained by reactions of the respective basic carbonates with the acid. The infrared spectra of the salts, compared with the spectr um of the free acid, showed shifts that were interpreted in terms of a nion coordination to the lanthanide ions. The results suggested that i n all compounds the lanthanides are eigth-coordinated, with bidentate carboxylate anions and two water molecules bonded to the central ions. For the (2)G(7/2), (4)G(5/2)<--I-4(9/2) and P-2(1/2)<--I-4(9/2) trans itions in the absorption spectrum of the neodymium(III) salt, the para meters beta=0.993 and b(1/2)=0.0592 were indicative of a small covalen t character for the Nd(III)-oxygen bonds. The emission spectra of the europium and terbium compounds were investigated; that of the europium compound was interpreted in terms of C-2v symmetry. Thermogravimetric analyses showed loss of two water molecules up to 180 degrees C, foll owed by complete decomposition to the respective oxides at about 900 d egrees C.