Ferroelasticity-like and solvent affect the magnetism of a copper-organic radical one-dimensional coordination polymer

The one-dimensional coordination polymers {[CuII(hfac)2]3(m-BNN)}n·nCH2Cl2 (1·CH2Cl2, P1̄) and {[CuII(hfac)2]3(m-BNN)}n (1', P2/n), hfac = hexafluoroacetylacetonate and m-BNN = meta-phenylene bis(nitronyl-nitroxide), were obtained from CH2Cl2 and CHCl3, respectively. 1·CH2Cl2 is transformed to 1 at 335 K. Their magnetic susceptibilities differ in both magnitude and temperature dependence behavior. 1 and 1' undergo a ferroelastic-like phase transition at 110 K and an unidentified one at 37 K. There is a subtle long relaxation of this ferroelastic-like ordered state.