Mixed-Valence Cobalt(II/III)–Octacyanidotungstate(IV/V) Ferromagnet

We report a mixed-valence cobalt­(II/III)–octacyanidotungstate­(IV/V) magnet, [Co^II(H₂O)]₂[Co^III{μ-(<i>R</i>)-1-(4-pyridyl)­ethanol}₂]­[W^IV(CN)₈]­[W^V(CN)₈]·5H₂O. Synchrotron-radiation X-ray single crystal structural analysis, infrared spectrum, and density-functional theory (DFT) calculation indicate that this compound has a chiral structure with the <i>P</i>2₁ space group and both Co^II(<i>S</i> = 3/2)–NC–W^V(<i>S</i> = 1/2) and Co^III(<i>S</i> = 0)–NC–W^IV(<i>S</i> = 0) moieties, which are structurally distinguishable in the crystal structure. Magnetic measurements reveal that this compound exhibits ferromagnetism with a Curie temperature of 11 K and a coercive field of 1500 Oe, which is caused by the coexistence of the superexchange interaction in the Co^II–W^V chain and double exchange interaction between the chains