Synthesis, Characterization and Thermal Behavior of Solid-State Compounds of Light Trivalent Lanthanide Malonates

Abstract

In this study, compounds of hydrated lanthanide malonates were synthesized by precipitation of sodium malonates ion. Quantitative studies of the compounds obtained in the solid state, as well as the thermal behavior of these compounds were performed by thermal analysis (TG-DTA and DSC). Additional complementary studies were also performed using X-ray diffraction by the powder method (XRD), Evolved Gas Analysis (EGA) and complexometric titration with EDTA. Thus, the compounds synthesized in this work, ranging from lanthanum to gadolinium, were studied mainly in relation to their thermal properties, enabling to establish the stoichiometry, the decomposition steps and identify by EGA the main volatile products released during the decomposition. The qualitative study by XRD and FT-IR showed that the compounds were obtained in the crystalline state and metal-ligand coordination occurs by bidentate bonding and /or bridge, respectively. The interest in these compounds is due to the several applications of malonate ion, such as  industrial and biological, not to mention that the coordination of the lanthanide ions to the malonate ligand can provide them new properties which could be studied and explored forward.