DIOXOURANIUM(VI) COMPLEXES OF SOME MACROCYCLIC LIGANDS DERIVED FROM 2,6-DIFORMYL- AND 2,6-DIACETYLPYRIDINES AND SOME ALIPHATIC AND AROMATIC AMINES

摘要

The template condensation of 2,6-diformyl- and 2,6-diacetylpyridines and ethylenediamine (en), diethylenetriamine (DTA), triethylenetetraamine (TTA), p-phenylenediamine (PPN), o-phenylenediamine (OPN) and dioxaoctane-l,8-diamine (DODN) in the presence of uranyl acetate dihydrate resulted in the formation of dioxouranium(VI) macrocyclic complexes. The isolated solid complexes have been characterized on the basis of elemental analyses, spectral (UV-Visible and IR), thermal (TGA and DTA) and magnetic measurements. The results suggest that the solid complexes consist of polymeric uranyl complexes with at least two uranyl ions attached to each other via the hydroxo bridges. Also, the IR spectra suggest that the macrocyclic ligands coordinate through the azomethine nitrogen (C=N) and the pyridyl nitrogens groups, while coordination in case of the complexes derived from 2,6-diformyl- and 2,6-diacetylpyridines with dioxaoctane-1,8-diamine occurs through the azomethine, pyridyl nitrogens and the ether oxygens (-CH_2-O_CH_2-). The thermal measurements indicate the amount of solvent inside and/or outside the coordination sphere and the mechanism of decomposition.