Inorganica Chimica Acta 324 (2001) 141 – 149 www.elsevier.com/locate/ica Synthesis, characterisation, crystal structures, and magnetic properties of one-dimensional oxalato-bridged metal(II) complexes with 3-hydroxypyridine and isoquinoline Oscar Castillo a , Antonio Luque a, *, Francesc Lloret b , Pascual Roma ´n a a Departamento de Quı ´mica Inorga ´nica, Uniersidad del Paı ´s Vasco, Apartado 644, E-48080 Bilbao, Spain b Departament de Quı ´mica Inorga `nica, Facultat de Quı ´mica, Uniersitat de Vale `ncia, Dr Moliner 50, E-46100 Burjassot, Valencia, Spain Received 18 April 2001; accepted 23 July 2001 Abstract One-dimensional oxalato-bridged metal(II) compounds of formula [M(-ox)(L) 2 ] n [L =3-hydroxypyridine (pyOH) or isoquino- line (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(-ox)(pyOH) 2 ] n [M=Co (1), Ni (2)] are isomorphous and crystallise in the orthorhombic space group Pnab. The compounds [M(-ox)(isq) 2 ] n [M=Co (3), Ni (4), Cu (5)] are also isomorphous and belong to the monoclinic space group C 2/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 A  . 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. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Crystal structures; Magnetic properties; Oxalato-bridged complexes; Metal complexes 1. Introduction During the last two decades, research for coordina- tion metal complexes with one-dimensional structures have been particularly active, from both experimental and theoretical points of view, mainly because these systems are suitable examples for developing models aimed at understanding the fundamental factors gov- erning the interactions in extended lattices [1–4]. Molecular-based ferromagnets, conductors, and non- linear optical materials represent several applications of one-dimensional coordination polymers. In this con- text, and in the framework of our current research work dealing with the preparation and magneto-struc- tural characterisation of polynuclear oxalate-containing metal complexes, we report herein on the synthesis, crystal structures, and the magnetic behaviour of a family of one-dimensional chains of general formula [M(-ox)(L) 2 ] n , where L =3-hydroxypyridine [M(II) = Co (1), Ni (2)] and isoquinoline [M(II) =Co (3), Ni (4), Cu (5)]. The oxalate anion is a very versatile ligand that can adopt a large range of coordination modes [5]. This fact and its ability to transmit electronic effects between magnetic centres as far away as 5 A  constitute the basis for the development of synthesis and magneto-struc- tural investigations of oxalato-bridged compounds [6,7]. Even though a great variety of oxalato-bridged polynuclear complexes have been structurally and mag- netically characterised (from discrete dimers to three-di- mensional systems), only a few examples of one-dimensional oxalato-bridged copper(II) compounds are known [8] and extended polymeric structures of nickel(II) [9] and cobalt(II) are scarce [9 – 12]. * Corresponding author. Tel.: +34-964-012 701; fax: +34-944- 648 500. E-mail address: qipluara@lg.ehu.es (A. Luque). 0020-1693/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved. PII:S0020-1693(01)00568-0