Comparison between thermal analysis and mass spectroscopic studies of uranyl oxinates

The 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,6-dinitro derivatives of oxine (ligandsL₁,–L₄) were used to prepare uranyl chelates (A₁–A₄). Thermal analysis (DTA) and mass spectroscopic studies were performed. The stoichiometries of the chelates were determined by elemental analysis, molecular weight determination applying an -spectroscopic liquid scintillation counter and mass spectral measurements. The uranylligand ratios were found to be 11 for A₁, 13 for A₂, 12 (monohydrate) for A₃, and 12 forA₄. The correlation between the thermal analysis and mass spectra was examined. The activation energy required for each step of thermal degradation of the ligands and chelates was calculated. The natures of most of the molecular ions obtained in the mass spectra were also explained.