An investigation of Prussian Blue analogues by Mossbauer spectroscopy and magnetic susceptibility

Abstract

The Mossbauer spectra and magnetic susceptibilities have been obtained for a series of Prussian Blue analogues of general formula MjA[MB(CN)6]k[middle dot]mH2O where MA and MB are transition metal ions, j and k vary with the oxidation states of MA and MB and m typically has values from 8 to 14. The compounds were prepared from the hexacyano acids or with large quaternary ammonium counterions and are therefore not contaminated with alkali cations. In each analogue, A or B is iron and the second metal is Mn, Cu, Co, Cr or Ru. In each case it was possible to assign the site (A or B), oxidation state and spin state to each transition metal ion. This group of compounds are all class II mixed valence species from their colours, but do not show evidence of linkage isomerism or redox changes compared to the starting materials. The Mossbauer linewidths are consistent with the Ludi model of Prussian Blue.