The synergic extraction of the europium(iii)-bis-phenanthroline-tris-salicylate complex and the preparation and properties of analogous ternary rare earth complexes

Abstract

Solid ternary complexes of the composition M(phen) 2(R.C 6H 4.CO 2) 3 have been prepared from a number of rare earth cations, M 3+, with 1,10-phenanthroline (phen) and benzoic acid, salicylic acid, or p-hydroxybenzoic acid. Only those complexes formed with salicylic acid could be extracted by benzene from aqueous solutions of the components, and radiometric studies from solutions of constant ionic strength I=0.1 M (NaClO 4) showed the extractable species to be a bis-phenanthroline-tris-salicylate complex. Infrared studies of the solid complex suggest the presence of both chelated and unchelated salicylate ions (HSal −). Fluorescence spectra indicate that the europium(III) complex is octa-coordinated and should be formulated as [Eu(phen) 2(HSal) 2]+[HSal] −. The partition coefficients of 1,10-phenanthroline and salicylic acid between benzene and water are 3.84 and 1.7, respectively, and the acid is dimerized in benzene with K dim=35.