pH-Metric Study on Tervalent Yttrium and Lanthanide Chelates Involving 2-Hydroxy-2-Methyl Propanoic Acid as Secondary Liagand

Abstract

Studies on the formation constants for the complexes of the type
ML and MAL (where M = La(III), Ce(III), Pr(III), Nd(III), Sm(lll),
Eu(IIl), Gd(III), Th(III), Dy(III), Ho(lII), Er(III), Yb(lII), Lu(III)
and Y(lII), A = disodium  salt of ethylenediamine-tetraacetic acid
and HL = 2-hydroxy-2-methyl propanoic acid) have been made at
25°C and 0.1 M ionic strength (NaCIO₄) by applying Irving-Rossotti
pH titration technique and its extension to ternary systems.
The order of stability of the MAL complexes was found to be La(III)
< Ce(Il) < Pr(lII) < Nd(lII) < Sm(lll) < Eu(lII) > Gd(lII) < Tb{III)
< Dy(lII) < Ho(lII) < Er(lII) = Yb(III) < Lu(III).