Synthesis, characterisation and magnetic properties of cobalt (II) complexes with 3-hydroxypicolinic acid (HpicOH):: [Co(picOH)2(H2O)2] and mer-[N(CH3)4][Co(picOH)3] • H2O

Two complexes with Co2+ and 3-hydroxypicolinic acid, [Co(picOH)(2)(H2O)(2)] (I) and mer-[N(CH3)(4)][Co(picOH)(3)] center dot H2O (II), have been synthesised and characterised. using single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, and thermoanalytical measurements. The 3-hydroxypicolinate ligands are coordinated to the Co2+ centres via its typical N,O-chelating coordination fashion. While in I the presence of two coordinated water molecules leads to the formation of a neutral [Co(picOH)(2)(H2O)(2)] complex which is strongly hydrogen bonded to another four neighbouring complexes, in II the inclusion of a third picOH- ligand leads to an anionic octahedral complex, [Co(picOH)(3)](-), in which all the N- and O-atoms are occupying mer positions. The properties of these two compounds were further investigated by measuring their magnetic behaviour. (c) 2005 Elsevier Ltd. All rights reserved.