The Chemical behavior of binary systems RE(III)-NEB(RE=La→Nd,Sm→Lu,Y;NEB=2,2′,2″nitrilotris(2,1ethanediyloxy)tris benzoic acid)were investigated potentiometrically at 25℃ and 020 mol/L(KNO3)ion strength in 50% methanolwater mixture.Computer programs MAGEC?MINIQUAD82 and MIQUV were employed for obtaining the results.It was found that two chemical models of binary complexes 112 and 111(RE∶L∶H,L=deprotonated NEB,H=proton)were existed in researching systems,and an apparent"tetrad effect"was also observed for the stability constants logβ112 and logβ111.In addition,the relative position of ytterbium was discussed.
