Influence of Substituent Positions in Benzene Ring on the Properties of Co(II) 2,3- , 3,5- and 2,6-Dimethoxybenzoates

Wiesl ´awa Ferenc1 *, Agnieszka Walków-Dziewulska1, Jan Sarzy×ski2

1 Department of General and Coordination Chemistry, Maria Curie-Skl ´odowska University, Pl 20-031, Lublin, Poland
2 Institute of Physics, Maria Curie-Skl ´odowska University, Pl 20-031, Lublin, Poland

The physico-chemical properties and thermal stability in air of Co(II) 2,3-, 3,5- and 2,6-dimethoxybenzoates were compared and the influence of the position of –OCH3 substituent on their thermal stability was investigated. The complexes are crystalline, hydrated and anhydrous salts with pink colour. The carboxylate ions are a monodentate, bidentate chelating or bridging and tridentate groups. The thermal stability of analysed Co(II) dimethoxybenzoates was studied in the temperature range of 293–1173 K. The positions of methoxy groups in benzene ring influence the thermal properties of studied complexes. Their different thermal properties are markedly connected with the various influences of inductive, mesomeric and steric effects of the OCH3 substituent on the electron density in benzene ring. The magnetic susceptibilities of the complexes were measured over the range of 76–300 K and the magnetic moments were calculated. The results show that 2,3–, 3,5- and 2,6-dimethoxybenzoates of Co(II) are high-spin complexes with weak ligand fields.

Keywords: 2,3-, 3,5- and 2,6-dimethoxybenzoates of Co(II), magnetic moments of Co(II) complexes, thermal stability, FTIR spectra of Co(II) compounds