FeOOH6

FeOOH6 is a chemical formula that occasionally appears in theoretical discussions or as a potential misnotation, but it is not recognized as a distinct, well-characterized compound in standard mineralogy or coordination chemistry. As written, FeOOH6 would consist of one iron atom, two oxygen atoms, and six hydrogen atoms per formula unit, which would imply iron in a low oxidation state if treated as a neutral composition. However, iron oxyhydroxide chemistry is typically described by formulas such as FeO(OH) (goethite) or FeOOH in various polymorphs, where the stoichiometry reflects a single hydroxide ligand per iron and well-established mineral structures.

There is no widely cited, isolable FeOOH6 compound in recognized databases or mineralogical literature. The stability of such a species is uncertain, given the tendency of iron(II) to oxidize under many conditions and the propensity for hydrolysis and structural rearrangement in hydroxide-rich environments. In solution, iron often exists as hydrated or oxide-bearing species that do not correspond to a discrete FeOOH6 unit. Consequently, if FeOOH6 is encountered, it is usually interpreted as a misprint or as shorthand for a related, more conventional iron oxyhydroxide motif, such as FeO(OH) or Fe(OH)3, or as part of a polymeric iron–hydroxide network rather than a discrete molecular compound.

See also: goethite, lepidocrocite, akaganite, iron oxyhydroxide.