Comparison of some properties of 2,3- and 3,5-dimethoxybenzoates of light lanthanides

The physico-chemical properties and thermal stability in air of the light lanthanide 2,3- and 3,5-dimethoxybenzoates were studied and compared in order to observe if there is influence of the position of -OCH₃ substituents in benzene ring on their properties, mainly on their thermal stability. The complexes of both of two series are crystalline, hydrated or anhydrous salts with colours typical of Ln³⁺ ions. The carboxylate group shows the different coordination modes. It may coordinate as a bidentate, chelating or tridentate chelating-bridging ligand. The thermal stabilities of 2,3- and 3,5-dimethoxybenzoates of light lanthanides were studied in the temperature range 293-1173 K. The solubilities of 2,3- and 3,5-dimethoxybenzoates of these elements in water at room temperature are in the orders of 10^-3-10^-2 mol dm^-3 and 10^-4 mol dm^-3, respectively. The various positions of -OCH₃ groups in benzene ring influences some physico-chemical properties of these compounds. This revised version was published online in July 2006 with corrections to the Cover Date.