Synthesis, characterisation, crystal structures, and magnetic properties of one-dimensional oxalato-bridged metal(II) complexes with 3-hydroxypyridine and isoquinoline

one-dimensional oxalato-bridged metal(II) compounds of formula [M(mu -ox)(L)(2)](n) [L = 3-hydroxypyridine (pyOH) or isoquinoline (isq)] have been synthesised and characterised by FT-IR spectroscopy, TG-DTA techniques, variable-temperature magnetic measurements and X-ray diffraction methods. The complexes [M(mu -ox)(pyOH)(2)](n) [M = Co (1), Ni (2)] are isomorphous and crystallise in the orthorhombic space group Pnab. The compounds [M(mu -ox)(isq)(2)](n) [M = Co (3), Ni (4), Cu (5)] are also isomorphous and belong to the monoclinic space group C2/c. Crystal structures consist of zig-zag chains in which cis-[M-(L)(2)](2+) units are sequentially bridged by bis-bidentate oxalato ligands with intrachain M . . .M distances in the range 5.38-5.49 Angstrom. The divalent metal centres have a distorted octahedral coordination with four oxygen atoms from two symmetry-related bridging oxalato ligands and the pyridinic nitrogen atoms from two cis-oriented aromatic ligands. Magnetic susceptibility measurements in the temperature range 2.0-300 K show the occurrence of antiferromagnetic intrachain interactions for the compounds 1-4 and a weak ferromagnetic coupling for 5. (C) 2001 Elsevier Science B.V. All rights reserved.