FeFeCNxHO

FeFeCNxHO refers to a class of chemical compounds containing iron (Fe), cyanide (CN), and potentially other elements like hydrogen (H) and oxygen (O). The subscript 'x' indicates that the stoichiometry of cyanide in these compounds can vary. These materials are often encountered as pigments, particularly Prussian blue and its related analogues, which are complex coordination polymers.

Prussian blue, with the idealized formula Fe4[Fe(CN)6]3, is a well-known example. However, variations in synthesis can lead to materials with different ratios of iron and cyanide. The presence of hydrogen and oxygen is common, often incorporated as water molecules (hydrates) or hydroxide groups, influencing the exact composition and properties. These compounds are typically characterized by their intense blue color, which arises from charge transfer transitions between the iron ions.

FeFeCNxHO compounds find applications as pigments in paints, inks, and ceramics due to their stability and vibrant hue. They have also been explored for various other uses, including in electrochemical devices, catalysis, and as potential treatments for heavy metal poisoning. The specific properties and applications depend heavily on the precise composition, crystal structure, and oxidation states of the iron ions present. Research continues to explore new synthetic routes and applications for this diverse group of iron-cyanide-based materials.