Thermal and spectral properties of di-and trimethoxybenzoates of silver (I)

Abstract

Introduction The carboxylates of many cations play an important role in inorganic and bioinorganic chemistry and in a great number of various biological processes they are component of several vitamins and drugs [1, 2]. 2,3-, 2,4-, 2,6-, 3,4-, 3,5-Dimethoxy-and 2,3,4-and 3,4,5-trimethoxybenzoic acids are crystalline solids sparingly soluble in water. Their anions have the following formulae: 63 Abstract: The complexes of silver(I) with 2,3-, 2,4-, 2,6-, 3,4-, 3,5-dimethoxy-, and 2,3,4-and 3,4,5-trimethoxybenzoic acid anions have been synthesized and characterized by elemental analysis, IR spec-troscopy, thermogravimetric and X-ray studies. Their solubility in water has been also determined at 293K. All analysed complexes were found to be crystalline, anhydrous compounds with low symmetry. The carboxylate groups act as bidentate or monodentate ligands. The thermal stability of compounds has been examined in air in temperature range of 293-1173K. The analysed complexes were found to be stable at room temperature and their solubilities in water at 293K to be in the order of 10-4 mol.dm-3. In the presented acid molecules there are two kinds of substituents:-COOH and-OCH 3. The first one, as an electron acceptor decreases the electronic density of benzene ring molecule while-OCH 3 as being its donor decreases the acidity of benzoic acid derivatives.These distinct characters of above presented two kinds of substituents influence the properties of methoxybenzoic acid iso-mers and their compounds. Moreover the mesomeric, inductive and steric effects are known to affect the properties of aliphatic and aromatic compounds. The inductive effects of each methoxy-group causing the delocalization of the electrons in the complex molecule change its energy state and bring about the conjugation of electrons. Furthermore the mesomeric effects caused by those groups rise the energetic changes in the molecule of the organic compound. The inductive effect created by those sub-stituents influences mainly the electron density in benzene ring in their meta-position, while in