Electronic States of Cobalt Iron Cyanides Studied by 57Fe Mössbauer Spectroscopy

The electronic states of cobalt iron cyanides were observed using 57Fe Mössbauer. It was revealed that Prussian blue analogs Co1.5[Fe(CN)6]6H2O and K0.5Co1.25[Fe(CN)6]3.6H2O have FeIII(low spin) and FeII(low spin), respectively, at both room temperature and 4 K. In Co1.5[Fe(CN)6]6H2O, a magnetic hyperfine interaction was observed at low temperature. Moreover, the Mössbauer spectra provided clear evidence for an internal electron transfer from FeII to CoIII in K0.5Co1.25[Fe(CN)6]3.6H2O by red light illumination at low temperature.