Synthesis and characterization of some 3-phenyl-4-arylazo-5-pyrazolones with La(III), Ce(III), Th(IV), and UO2(VI) complexes

La(III), Ce(III), Th(IV) and UO2(VI) chelates with 3-phenyl-4-arylazo-5-pyrazolones have been synthesized and were characterized by several analytical tools such as elemental analyses, IR, NMR, TG and molar conductance techniques. The data obtained show that all of the prepared complexes contain water and/or alcohol molecules in their coordination sphere and the ligands form 1:1 and 1:2 complexes which are in good agreement with the proposed formulae. The NMR data of the prepared ligands show the existence of the ketonic structure rather than the enolic form. The TG data revealed no crystal water outside the coordination sphere. The azopyrazolone ligands act as neutral bidentate ligands bonded to the metal ions through the oxygen atom of the carbonyl group and the a nitrogen of the arylazo group. All solid chelates prepared behave as non-electrolytes in DMF solution. The coordination numbers of the prepared chelates are ranging from 6 to 12 for 1: 1 and from 7 to 12 for 1:2 chelates.