Studies on the stability of rare earth ion-N,N'-dialkyl-1,10-phenanthroline-2,9-dimethanamine binary complexes

The stability constants of Ln - L [Ln = La( III), Ce(III), Pr( III), Nd(III ), Sm(III), Eu(III), Gd(III), Tb(III) , Dy(III), Ho(III), L = N, N' - dialk yl - 1,10 - phenanthroline - 2,9 - dimethanamine, in which alkyl group deno tes -CH3, -CH2CH3, -(CH2)(2)CH3, -(CH2)(3)CH3, -CH(CH3)(2), -C(CH3)(3) ] bi nary complexes have been determined by pH potentiometric titration method a t (25 +/- 0.1)degreesC, I= 0. 1 mol . dm(-3) NaClO4. The probable structure s of the corresponding complexes were proposed. The influence of the metal ions and the substituents on the stability of binary complexes is reported in detail. The stability difference between the complexes of rare earth ion and the corresponding complexes of Cu(III) ion is also discussed. The stab ility constants of the corresponding binary complex of radioactive Pm(III) ion are estimated by linear regression.