By using NMR spectroscopy, this study provides novel insights into the M(III)-TEDGA interaction in [M(TEDGA)₃]³⁺ complexes (M=Ln, Am). The chemical shift analyses solidify the assumption of almost identical metal-ligand interaction between Am(III)−O and Ln(III)−O.

Abstract

NMR spectroscopy studies on the complexation of La(III), Sm(III), Lu(III), Y(III) and Am(III) with N,N,N′,N′-tetraethyldiglycolamide (TEDGA) have been performed. Initial studies concerning the stoichiometry of the complexes prove the formation of [M(TEDGA)₃]³⁺ in D₂O and [M(TEDGA)_1-3]³⁺ in CD₃CN. Decreasing the solvent polarity translates to an increase of the complex stability as shown by complementary TRLFS studies with Cm(III). Due to delocalization of the lone electron pair of the amide nitrogen atom, the M(III)−O interaction has been studied indirectly by collecting ¹³C and ¹⁵N NMR data. The observed chemical shifts prove that the interaction of the trivalent ions, An(III) and Ln(III), and TEDGA is almost identical.