Physicochemical investigation of lanthanon(III) chelates of monoprotic tridentate ligands possessing N-O-O moiety

O-(N-furan-2-acetylimino) benzene sulphonic acid (HFB) and O-(N-furan-2-acet ylimino) ethane sulphonic acid (HFE) and their lanthanon(III) chelates were synthesised and studied by physicochemical techniques. Irving-Rossotti method wa s followed to determine the dissociation constant of the ligands and formation constants of their chelates with La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III), Ho(III) and Er(III) metals in 30 per cent (v/v) dioxane-water medium (μ= 0.1M, 0.05M and 0.01M NaClO4) at 25deg, 35deg and 45degC. The order of stability constants of the metal chelates was found in accordance to the lanthanide-contraction. Solid lanthanon chelates were characterised by molecular-mass, elemental analyses, magnetic moment, conductance, HNMR, and IR spectra. 1:3 (metal-ligand) stoichiometry was displayed by the metal chelates in which the lanthanon showed nine coordination number. (author). 6 refs., 2 tabs