CHELATES OF PRASEODYMIUM(III), NEODYMIUM(III), SAMARIUM(III), GADOLINIUM(III), HOLMIUM(III), ERBIUM(III), THULIUM(III) AND YTTERBIUM(III) AND SOME SYMMETRICAL 1,5-DIPHENYL-3-CYANOFORMAZANS

Potentiometric, conductimetric, ir, TG, molar conductance and magnetic susceptibility studies have been carried out on the complexes of triv alent Pr, Nd, Sm, Gd, Ho, Er, Tm and Yb with some symmetric 1,5-diphen yl-3-cyanoformazans. The ionisation constants of the ligands and the f ormation constants of their metal chelates have been determined potent iometrically in solution. Complexation has also been studied by a cond uctimetric titration method.