Synthesis, crystal structure, thermal analysis and magnetic behaviour of a novel one-dimensional polymeric pyridinium chlorocuprate(II): (Hpy)2[Cu3Cl8(H2O)2]

A one-dimensional polymeric pyridinium chlorocuprate (HPy)2[Cu3Cl8(H2O)2], an intermediate between (HPy)CuCl3 and CuCl2·2H2O, has been synthesized and characterized by X-ray analysis. The structure contains [Cu3Cl8(H2O)2]n2n- chains in which both square-pyramidal and octahedral CuII exist. The chains are composed of linked [Cu2Cl6]2- dimers and CuCl2(H2O)2 monomeric units. On being heated in the solid state the compound undergoes dehydration followed by dehydrohalogenation to produce a pyridine complex of CuII: [Cu3Py2Cl6]. Magnetic studies reveal ferromagnetic coupling within the chains with an intradimer exchange coupling of 12.1 cm-1 and a dimer-monomer exchange coupling of 1.34 cm-1.