SYNTHETIC AND SPECTROSCOPIC INVESTIGATIONS OF SOME DIOXOURANIUM(VI) COMPLEXES OF MULTIDENTATE DISALICYLALDEHYDE ADIPOYLDIHYDRAZONE

Reactions of disalicylaldehyde adipoyldihydrazone with uranyl acetate dihydrate and uranyl nitrate hexahydrate in aqueous and ethanolic media under different experimental conditions were studied and the resulting complexes with the compositions [UO2(H2L2)(H2O)]n, [UO2(H2L2)]n3nH2O, [UO2(H3L2)(CH3COO)]n3nH2O, [UO2Zn(L2) (H2O)2]n2nH2O, [(UO2)2(H2L2)(C2O4)]n2nH2O and [(UO2)2(L2)(py)2(H2O4] were characterized on the basis of elemental analyses, EDAX and thermoanalytical data. The structural assessment of the complexes was carried out by using molar conductance, magnetic moment and ESR data and IR, electronic and H-1 NMR spectroscopy. In the complexes, the ligand functions as a bridging monobasic tetradentate, dibasic hexadentate and tetrabasic hexadentate ligand, and exhibits keto-enol tautomerism. The acetate and oxalate groups act as chelating bidentate and bridging tetradentate ligands. The complexes are considered to involve seven, eight, nine and ten coordinated uranium atoms with ligand atoms arranged in the equatorial plane around the linear uranyl group and in the heterobimetallic complex [UO2Zn(L2)(H2O)2]n2nH2O the zinc atom is considered to have tetrahedral stereochemistry.