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

Abstract

One-dimensional oxalato-bridged metal(II) compounds of formula [M(μ-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(μ-ox)(pyOH) 2] n [M=Co ( 1), Ni ( 2)] are isomorphous and crystallise in the orthorhombic space group Pnab. The compounds [M(μ-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 Å. 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.