Aqueous complexation of trivalent lanthanide and actinide cations by N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine

The aqueous complexation reactions of trivalent lanthanide and actinide cations with the hexadentate ligand N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) have been characterized using potentiometric and spectroscopic techniques in 0.1 M NaClO4. At 25 degrees C, the stability constant of Am(TPEN)(3+) is two orders of magnitude larger than that of Sm(TPEN)(3+), reflecting the stronger interactions of the trivalent actinide cations with softer ligands as compared to lanthanide cations. (C) 2000 Elsevier Science S.A. All rights reserved.