Effect of p-tert-butylcalix[4]arene fitted with phosphinoyl pendant arms as synergistic agent in the solvent extraction of trivalent lanthanoids with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and structural study of solid complexes by IR, NMR and X-ray

The synergistic solvent extraction of five selected lanthanoid ions (La3+, Nd3+, Eu3+, Ho3+ and Lu3+) with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (HL) and 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis-(dimethylphosphinoylmethoxy)calix[4]arene, (S) in CHCl3 has been studied. It was found that in presence of this phosphorus-containing calix[4]arene the lanthanoid ions have been extracted as [LnL(3)S(2)]. The values of the equilibrium constants and the separation factor have been calculated. The influence of the synergistic agent on the extraction process has been discussed. Elemental analysis, IR, H-1 NMR, F-19 NMR spectra and X-ray have shown that the complex of Eu(III) with HL is eight coordinated and its composition can be represented with the formula [EuL2(C2H5OH)(4)]Cl as well as that the coordination polyhedron is distorted square antiprism. The stoichiometry ([EuL2S]Cl) and the structure of the solid complex of Eu(III) with HL and S were proposed using elemental analysis, IR, H-1 NMR, F-19 NMR and P-31 NMR data. (C) 2008 Elsevier Ltd. All rights reserved.