Thermal Stability of 2,3,4-, 2,4,5- and 3,4,5-tri- Methoxybenzoates of Light Lanthanides

The physico-chemical properties and thermal stability in air of light lanthanide 2,3,4-, 2,4,5- and 3,4,5-trimethoxybenzoates were compared and the influence of the position of –OCH³ substituent on their thermal stability was investigated. The complexes of these series are crystalline, hydrated or anhydrous salts with colours typical of Ln³⁺ ions. The carboxylate group is a bidentate, chelating ligand. The thermal stability of 2,3,4-, 2,4,5- and 3,4,5-trimethoxybenzoates of rare earth elements was studied in the temperature range 273–1173 K. The positions of methoxy groups in benzene ring influence the thermal properties of the complexes and their decomposition mechanism. The different thermal properties of the complexes are connected with various influence of inductive and mesomeric effects of –OCH₃ substituent on the electron density in benzene ring. This revised version was published online in August 2006 with corrections to the Cover Date.