High-Tc Molecular-Based Magnets: Ferrimagnetic Mixed-Valence Chromium(III)-Chromium(II) Cyanides with Tc at 240 and 190 Kelvin

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Science  03 Dec 1993:
Vol. 262, Issue 5139, pp. 1554-1557
DOI: 10.1126/science.262.5139.1554


Molecular-based magnets with high magnetic-ordering temperatures, Tc, can be obtained by mild chemistry methods by focusing on the bimetallic and mixed-valence transition metal µ-cyanide of the Prussian blue family. A simple orbital model was used to predict the electronic structure of the metal ions required to achieve a high ordering temperature. The synthesis and magnetic properties of two compounds, [Cr5(CN)12].10H2O and Cs0.75 [Cr2.125(CN)6]·5H2O, which exhibited magnetic-ordering temperatures of 240 and 190 kelvin, respectively, are reported, together with the strategy for further work.