Prussian Blue – [Fe(III)]₄[Fe(II)(CN)₆]₃

The low spin Fe(II) ions are linked in an octahedron to 6 carbons, whilst the high spin Fe(III) ions are linked in an octahedron to 6 nitrogens.

Prussian blue, [Fe(III)]₄[Fe(II)(CN)₆]₃. The iron ions are linked through cyanide, forming a cubic unit cell. Shaded squares (X) show regions in the structure where cations or water molecules may reside.