COMPLEXATION AND ELECTRONIC-SPECTRA OF NEODYMIUM(III)-AMINO ACID-1,10-PHENANTHROLINE SYSTEMS IN AQUEOUS-SOLUTION

Complexation of neodymium(III)-glutamate(glu)-phenanthro, neodymium(II I)-aspartate(asp)-phenanthroline(phen) ternary systems and the corresp onding binary systems in aqueous solution are discussed at various val ues of pH. Based on change regularity of hypersensitive transition int ensities, the neodymium(III)-aspartate-phenanthroline ternary complex has a general formula of Nd(asp)(3)phen, but the composition of the co mplex of Nd(III) with glutamate and phenanthroline is complicated and has not been determined. The electronic spectra of these complexes wer e studied, Slater-Condon parameters F-ks and the Lande parameter xi(4f ) were obtained. The rms deviation between calculated and observed ene rgy levels is less than 43 cm(-1). Bonding in these complexes are also investigated and bonding parameters calculated. The results show that Nd(III) and amino acids form complexes by ionic linkage with carboxyl ic oxygens, but with some weak covalency. Besides, the degrees of cova lency in ternary complexes are larger than those in binary complexes.