Two 3D coordination assemblies with same cluster configuration showing different magnetic behaviors: a ferromagnetic {[W(CN)8Co2(DMF)8][NO3]}n and a paramagnetic {W(CN)8Cu2(py)8}n

Abstract

Treatment of molecular building block [W(CN)₈]³⁻ with Co(NO₃)₂·6H₂O or Cu(ClO₄)₂·6H₂O in different reaction conditions affords two 3D (three-dimensional) metalloligand-bridged coordination polymers {[W^V(CN)₈Co₂(DMF)₈][NO₃]}_n1 and {W^IV(CN)₈Cu₂(py)₈}_n2, respectively. The single-crystal X-ray structural analysis shows that both polymers 1 and 2 crystallize in the tetragonal crystal system with space group of I4₁/a and possess the similar 3D framework in a diamondoid topology geometry, although [W(CN)₈]³⁻ ion was reduced into [W(CN)₈]⁴⁻ in polymer 2 during the reaction process. The magnetic studies on coordination polymers 1 and 2 indicate that polymer 1 shows the typical ferromagnetic property with an ordering temperature of about 5 K but polymer 2 exhibits paramagnetic behavior due to the diamagnetic octacyanometalate bridge –NC–W^IV(S = 0)–CN–.