ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Physicochemical Properties of 2,3- and 3,5-Dimethoxybenzoates of Co(II), Ni(II), and Cu(II)

W. Ferenc, A. Walków-Dziewulska, and P. Sadowski

Department of Inorganic and General Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, PL-20 031, Lublin, Poland

E-mail: wetafer@hermes.umcs.lublin.pl

Received: 16 September 2004

Abstract: Some physicochemical properties of 2,3- and 3,5-dimethoxybenzoates of Co(II), Ni(II), and Cu(II) were studied and compared to observe the influence of the position of —OCH3 substituents in benzene ring on these properties. The compounds of studied series are crystalline hydrated or anhydrous salts. The carboxylate group in analyzed dimethoxybenzoates shows the various coordination modes (a monodentate or a symmetrical, bidentate chelating, or bridging). The thermal stabilities of 2,3- and 3,5-dimethoxybenzoates of Co(II), Ni(II), and Cu(II) were investigated in air in the range of 293—1273 K. Their solubilities in water at room temperature are in the orders of 10⁻⁴—10⁻³ mol dm⁻³ and 10⁻⁵—10⁻³ mol dm⁻³. The magnetic susceptibilities for the analyzed dimethoxybenzoates were measured over the range of 77—300 K and the magnetic moments were calculated. The results reveal that the complexes of Ni(II) and Co(II) are the high-spin ones and those of Cu(II) probably form dimers. The electronic spectra of the studied compounds were also recorded and the values of the change of absorption bands were observed for 3,5-dimethoxybenzoates of Co(II), Ni(II), and Cu(II) greater than for 2,3-dimethoxybenzoates of those elements. The various positions of —OCH3 groups in benzene ring in the studied dimethoxybenzoates cause the different steric effects in the compounds. From the obtained results it appears that complexes of d-electron elements with 3,5-dimethoxybenzoic acid anion contain the greater number of water molecules and have greater thermal stability than 2,3-dimethoxybenzoates of those elements.

Full paper in Portable Document Format: 595a324.pdf

Chemical Papers 59 (5) 324–331 (2005)