Syntheses, structures and magnetic properties of three-dimensional co-ordination polymers constructed by dimer subunits

The crystal structures and magnetic properties of compounds [M-II(apo)(N(CN)(2))(2)], where M=Co (1), Ni (2) or Mn (3), apo=2-aminopyridine N-oxide, have been determined. The structural analyses revealed that they are isomorphous, and all belong to monoclinic space group P2(1)/n. The metal(II) ions display distorted octahedral co-ordination, with four terminal N atoms of different [N(CN)(2)](-) ligands and two O atoms of different apo ligands. Two ions are bridged by two mu -O atoms to form a dimer subunit. Those dimers are further linked to each other by [N(CN)(2)](-) resulting in a three-dimensional structure. The magnetic properties of the compounds were investigated in the temperature range 2-300 K for 1 and 2 and 4-300 K for 3. The values for the intradimer spin coupling constant J were estimated to be -17.8, -40, -1.3 cm(-1) for 1-3, respectively, indicative of antiferromagnetic interaction.