Electronic effects of metal hexacyanoferrates: An XPS and FTIR study

A series of metal hexacyanoferrates (KxMy[Fe(CN)6]z·qH2O, M = Fe, Co, Ni and Cu) were prepared by co-precipitation. The yields obtained were dependent on the Pauling scale electronegativity, σM, of the metal M. Multiple C≡N stretching frequencies in the 1900-2200 cm−1 area of the infrared spectroscopy confirmed mixed oxidation states of the different metals in the metal hexacyanoferrates. X-ray photoelectron spectroscopy was used to determine the ratio between the metals as well as the ratio of each oxidation state present of the different metals, this was then used to derive the stoichiometry of the metal hexacyanoferrates. The comparison of results between infrared spectroscopy and X-ray photoelectron spectroscopy gave insight into the electron distribution and charge transfer within the structure.138