SYNTHESIS, SPECTRAL AND STRUCTURAL CHARACTERIZATION AND THERMAL-DECOMPOSITION KINETICS OF DINITRATO (N,N,N',N'-TETRA-N-BUTYL ALIPHATIC DIAMIDE)URANY(II) BY THERMOGRAVIMETRIC ANALYSIS

Uranyl complexes of the type [UO2(TBAD)(NO3)(2)], where TBAD is N,N,N' ,N'-tetra-n-butyl aliphatic diamide, Bu(2)NCO(CH2)(n) CONBu(2), with n being 1, 2, 3, 4, 6, 8 or 10, were all prepared (TBAD with n = 0 fail ed to form a complex of this type) and characterized by elemental anal ysis, and UV-vis and IR spectroscopy. The complexes were found to have a chelate structure with three bidentate ligands, one TBAD molecule a nd two NO3- groups, all coordinated through O atoms. Using single-crys tal XRD, the complex with n = 2 in TBAD was revealed to have a deforme d hexagonal bipyramid structure with a large organic ligand chelate ri ng. The thermal decomposition studies of the complexes were carried ou t in nitrogen atmosphere using TG-DTG techniques. The kinetic paramete rs (non-isothermal method) for the main TBAD decomposition step were e valuated using the method suggested by Malek, Sestak, Koga et al. Base d on the above characterizations the effects of carbon chain length in TBAD on the structure, stability, and thermal behaviour of the comple xes, were carefully observed and discussed. The results showed that no t only the E value, but also the TBAD decomposition pattern and mechan ism for the complex with n = 1 in TBAD are distinct from those of all the others.