One-dimensional spin chains from Cu-II ions and 2,5-bis(pyrazol-1-yl)-1,4-dihydroxybenzene

The purple colored coordination polymer [1 Cu](n) was obtained from 2,5-bis(pyrazol-1-yl)-1,4-dihydroxybenzene and CuBr2 in aqueous ammonia. The crystal structure of [1 Cu](n) was determined from high resolution X-ray powder diffraction data using the method of simulated annealing. In the solid state, [1 Cu](n) features largely independent linear chains, all of them being oriented parallel to the c-axis of the crystal. The Cu ions are coordinated in a square-planar fashion by two nitrogen atoms and two anionic oxygen donors. Magnetic susceptibility and magnetization measurements indicate the Cu ions in [1 Cu](n) to be antiferromagnetically coupled with a coupling constant of about 20 K