Ammonium hexacyanoferrate(II) is an inorganic compound with the chemical formula . A hygroscopic, yellowish-green monohydrate as well as a trihydrate exist. A sesquihydrate has been characterized. The compound loses NH3 on exposure to air and light.
Synthesis Ammonium hexacyanoferrate(II) can be prepared by the neutralization of ferrocyanic acid with ammonia solution followed by salting with ethanol:
Uses It is of research interest as a catholyte in flow batteries.
Reactions The compound decomposes with the sequential formation of (NH4)3[FeIII(CN)6], (NH4)3[FeII(CN)5], Fe[FeII(CN)6]3 (Prussian blue), and finally Fe2O3. Prussian blue nanoparticles as well as amorphous Fe2O3 nanoparticles can be prepared using this method.
Related compounds Double salts such as ammonium barium hexacyanoferrate(II) trihydrate (Ba(NH4)2[Fe(CN)6]·3H2O) have been characterized.
References