COMPLEXATION EQUILIBRIA OF N,N'-O-PHENYLENEBIS(SALICYLIDENEIMINE)

The ionization constants of the Schiff base ligand N,N'-o-phenylenebis (salicylideneimine) (sal-o-phn) and its stability constants with Fe-II I, Ni-II, Co-II, Zn-II, Cd-II, Ca-II and Mg-II have been determined fo r the first time in DMSO-water 80:20 wt/wt (T = 25 degrees C; I = 0.5 mol dm(-3) in NaClO4) by potentiometric methods. The monomer species [ ML] and [MHL](+) are found to be formed. In the case of Fe-III-sal-o-p hn the hydroxocomplex species [FeOHL] was also detected. Fe3+ was obse rved to be hydrolyzed to a much lesser extent in DMSO-water 80:20 wt/w t than in aqueous solution. (C) 1997 Elsevier Science Ltd.