The structure and magnetic properties of the 1-dimensional dihalide-bridged polymers Co(thiazole)2X2 (X = Cl, Br)

Full text: The isostructural polymeric compounds Co(thiazole)2X2 (X Cl (1), Br(2)) have been synthesised by the addition of thiazole to an ethanolic solution of the corresponding anhydrous cobalt halide. Powder X-ray and neutron diffraction measurements were used for structural determination. The structures were determined using powder neutron diffraction data and Rietveld techniques: (1) C2/c, a = 17.806(2) Angstroms, b 3.6806(6)Angstroms, c 14.807(3) Angstroms, β = 94.78(1) deg, V 967.1(3) Angstroms3, Z = 4; (2) C2/c, a = 18.079(3) Angstoms, b = 3.8138(8) Angstroms, c = 15.022(4) Angstroms, ,β = 92.71(1) deg, V = 1034.6(4) Angstroms3, Z = 4. Each linear polymer chain is composed of pseudo octahedral, high-spin Co2+ centres, doubly linked by halide bridges. Magnetisation measurements of 1 and 2 at S K between 0 and 10 kG reveals a metamagnetic transition between antiferromagnetic and ferromagnetic states. Low temperature susceptibility data have been fitted to a one-dimensional Ising model with a mean field correction and were found to be anisotropic with ferromagnetic intrachain interactions along the b-axis and weaker antiferromagnetic interchain interactions. Comparison of the magnetic properties is made with those observed for the Fe(II) analogue Fe(thiazole)2Cl2