Synthesis, crystal structure, thermal analysis and magnetic behavior 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 CuCl(2)(.)2H(2)O, has been synthesized and characterized by X-ray analysis [monoclinic, P2(1)/c, a = 7.8950(10), b = 14.144(2), c = 9.921(10) Angstrom, beta = 99.20(2)degrees]. The structure contains [Cu3Cl8(H2O)(2)](n)(2n-) chains in which both square-pyramidal and octahedral Cull 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 Cu-II: [Cu3Py2Cl6]. Other compounds, (HPy)(2)[CuCl4], CuPyCl2 and CuPy2Cl2, also produce [Cu3Py2Cl6] as an intermediate on thermal analysis. Magnetic studies reveal ferromagnetic coupling within the chains with an intradimer exchange coupling of 12.1 cm(-1) and a dimermonomer exchange coupling of 1.34 cm(-1). ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).