Complexes of lanthanide chlorides with macrocyclic polyethers

Abstract

Macrobicyclic polyether ligands I, II, III and IV have been shown [1] to form complexes with alkali salts having high formation constants even in water (10 5 l mol −1). Ln/Ligand La Nd Sm Gd I LaCl 3·I·2H 2O NdCl 3·I·H 2O GdCl 3·I·2H 2O II LaCl 3·II·2H 2O SmCl 3·II·H 2O GdCl 3·II·H 2O III LaCl 3·III·1.5H 2O NdCl 3·III·1.5H 2O SmCl 3·III· 1 2 H 2O GdCl 3·III·H 2O IV LaCl 3·IV·H 2O NdCl 3·IV·0.3H 2O GdCl 3·IV·H 2O ▪ These ligands provide potentially 7, 8, 8 and 9 oxygen atoms for coordination with a cation. We investigated the reaction between LaCl 3, NdCl 3, SmCl 3 and GdCl 3 and four ligands. Crystalline compounds were obtained all of stoichiometry LnCl 3:ligand = 1:1, as deduced from elemental analysis. The existence of crystals depends upon the presence of water, evidence of this was obtained from infra red spectra particularly in the 3000—3500 cm −1 region and from analysis. Preliminary X-ray diffraction measurements and the densities of laCl 3· II·xH 2O and LaCl 3·III·yH 2O gave values of x and y which are independent of elemental analysis. Summary of the compounds obtained. (see Table) A complete single crystal structure analysis of LaCl 3·II·H 2O has shown the crystals to contain (LaCl 2·II) + cations with the third chlorine ion and the water molecules occupying disordered sites in channels, similar to those in KCl·III·5H 2O[2] .