Thermal gravimetric (TG) and differential thermal (DTA) analyses were performed to characterize the thermal behavior and the
stoichiometry of uranyl bis-1,3-diketonate complexes (R1COCR2COR3)2 UO2x H2O, where R1,3=CH3; C2H5; C6H5; CF3; pNO2−C6H4; pCl−C6H4; pMe−C6H4; NH−C6H5; R2=H, C6H5 andx=1; 2. Based on the data obtained, a thermal degradation mechanism for each complex was proposed. The final degradation product
for all studied complexes was U3O8 oxide. The temperature of the first organic fragment rupture including the U-O (ligand) bond was taken as criterion for the
thermal stability of the metal-oxygen donor bond in these complexes. The observed stability order is in good agreement with
the IR determined constant force values,k, of the U-O (ligand) bond.