Synthesis, crystal structure, thermal behaviour and magnetic properties of a novel one-dimensional copper(II) complex containing neutral and deprotonated 3-hydroxypyridine ligands

The compound {[Cu(mu-3-pyO-N,O)(3-pyO)(3-pyOH)(H2O)]. 2 H2O}(n) (3-pyO(-)=pyridin-3-onato anion, C5H4NO-; 3-pyOH=3-hydroxypyridine, C5H5NO), has been prepared, its crystal structure determined and its thermal and magnetic properties characterised. The structure is made up of infinite one-dimensional chains running along the b axis of copper(ii) atoms linked by bridging N,O-bidentate pyridin-3-onato ligands with a Cu ... Cu distance of 7.030(2) Angstrom. The copper(ii) atom is in a distorted square-pyramidal environment with the basal plane formed by the nitrogen and the oxygen atoms of two bridging pyridin-3-onato ligands and the pyridinic nitrogen atoms of two terminal aromatic ligands in a trans arrangement. The apical position is filled by the oxygen atom from a water molecule. One of the two terminal aromatic ligands is a neutral 3-hydroxypyridine. Polymeric chains are held together by means of a three-dimensional network of O-w-H ... O- and O-H ... O- hydrogen bonding interactions in which there are channels parallel to the a axis that host solvated H2O molecules. These water molecules are connected to the polymeric chains by means of hydrogen bonds. In the thermal degradation of the title compound, free and co-ordinated water molecules are released in two overlapping endothermic processes between 40 and 90 degrees C. Magnetic measurements show an antiferromagnetic interaction between the metallic centres with a J (triplet-singlet gap) value of -16.4 cm(-1).