CATION-DRIVEN ELECTRON TRANSFER INVOLVING A SPIN TRANSITION AT ROOM TEMPERATURE IN A COBALT IRON CYANIDE THIN FILM

The electronic structure of a cobalt iron cyanide thin film, Na0.4Co1.3[Fe(CN)6]5H2O, was switched from FeIII(low spin)−CN−CoII(high spin) to FeII(low spin)−CN−CoIII(low spin) by exchanging cations in interstitial sites from Na+ to K+. The reverse process was also induced by replacing Na+ with K+. That is, the alkali cations in the interstitial sites dominate the electronic and spin states of the host compound. This type of switching phenomenon can be achieved by choosing a compound with both electronic degeneracy and zeolitic properties.