Determination of stability constants of 2-hydroxy-1-naphthalidene-4'-chloro-2'-methoxyaniline complexes with La3+, Y3+, Nd3+, Dy3+ and Gd3+

It has been generally concluded from previous work on the correlation between chelate stability and ionic radii that the stabilities of the tripositive lanthanide complexes should increase with decreasing cation radius or increasing atomic number. An examination of the stability constant data generally bears out this expectation but reveals an anomalous behaviour in some instances. A large amount of work done relates to O, O donors. However, complexes containing O and N functional groups (azomethines) have not been dealt with very extensively. This communication is a continuation of authors' work on Schiff bases. The new Schiff base, 2-hydroxy-1-naphthalidene-4'-chloro-2'-methoxyaniline has been selected to study a correlation, if any, between the stability constants and the ionic potentials of the trivalent lanthanides. (author)