Preparation of 57Fe enriched K4[Fe(CN)6] and K3[Fe(CN)6]

A simple method to prepare 57Fe enriched K4[Fe(CN)6] and K3[Fe(CN)6] is described. The yields of the products are much better than those reported in the literature so far. The enrichment is essential for 57Fe Moessbauer investigation in a variety of Prussiate type complexes and other inorganic compounds which are conveniently prepared from K4[Fe(CN)6] and K3[Fe(CN)6]. K4[Fe(CN)6] was obtained by reacting freshly prepared Fe(OH)3 with glacial acetic acid and treating with iron acetate in boiling aqueous solution of KCN. The novel feature of the procedure to obtain K3[Fe(CN)6] is that the oxidation of K4[Fe(CN)6] has been carried out in the solid state by passing chlorine gas over the powdered specimen. K3[Fe(CN)6] was crystallised from alkaline solution of this oxidised powder. The compounds were characterised by Moessbauer spectroscopy. (author)