Cobalt(II) complexes of 2-methanol-, 2,6-dimethanol- and 2-ethanolpyridines: syntheses, spectroscopic, thermal and structural characterizations of [Co 2(μ-Cl) 2(mpy) 4]Cl 2 · 2H 2O, [Co(dmpy) 2]Cl 2 and [Co(Cl) 4](Hpyet) 2 (mpy=2-methanolpyridine; dmpy=2,6-dimethanolpyridine and Hpyet=2-ethanolpyridinium)

Abstract

Cobalt(II) complexes of 2-methanol-, 2,6-dimethanol- and 2-ethanolpyridines have been prepared by the reaction of the corresponding protonated substituted pyridines with [Co(sac) 2(H 2O) 4] · 2H 2O, where sac is saccharinate, and characterised by elemental analyses, IR, UV–Vis, magnetic measurements and single crystal X-ray diffraction. The corresponding 2-methanolpyridine (mpy) complex [Co 2(μ-Cl) 2(mpy) 4]Cl 2 · 2H 2O is dimeric with chloro bridges and each cobalt(II) ion has an octahedral coordination with two chloro and two bidentate (N, O) ligands. In the 2,6-dimethanolpyridine (dmpy) complex [Co(dmpy) 2]Cl 2, dmpy exhibits a tripodal chelating coordination mode through the N and two hydroxyl O atoms forming a CoN 2O 4 chromophore. The protonated 2-ethanolpyridinium cation Hpyet serves as a non-coordinating, but hydrogen bonded counter ion in [Co(Cl) 4](Hpyet) 2. Based on the molecular structures, the electronic, IR spectra and thermal behavior of the complexes are discussed.