COMPLEXES OF CERIUM(III), THORIUM(IV) AND DIOXOURANIUM(II) WITH 8-(ARYLAZO)-7-HYDROXY-4-METHYLCOUMARIN DYES

Proton-ligand ionisation and metal-ligand stability constants of 8-(arylazo)-7-hydroxy-4-methylcoumarin complexes with Ce(III), Th(IV) and UO2II ions have been determined pH-metrically in 60% (v/v) ethanol-water mixture at 25-degrees and mu = 0.1. The order of stability constants was found to be Th(IV) > Ce(III) > UO2II. 1 : 1 and 1 : 2 (M : L) complexes are formed as evidenced by conductimetric studies. The complexes have been isolated in solid state and characterised on the basis of elemental analyses, thermal, ir and nmr spectral data.