A copper(II) octacyanotungsten(V)-based ferromagnet, Cu-3(II)[W-V(CN)(8)](2)(pyrimidine)(2)center dot 8H(2)O, was prepared. This magnetic material can reversibly adsorb and desorb n-propanol vapor and shows reversible variations in the crystal structure and magnetic properties. These changes are due to the coordination geometry switching of Cu-II between 6-coordinate and 5-coordinate.