Chemical Properties
green powder
Chemical Properties
Iron(III) fluoride is only sparingly soluble in water and insoluble in alcohol and ether.
When heated in hydrogen it is reduced to iron(II) fluoride and thence to the metal. In
aqueous solution the hydrolysis appears to be very slight ; in the presence of alkali metal
fluorides, complex fluorides of types MFeF4, M2FeF5.xH2O and M3FeF6 can be crystallized.
The magnetic behaviour of FeF3 is complicated; between 63° and 293°K the
susceptibility is field strength dependent. The trihydrate has a magnetic moment μ = 2-25 B.M. at 300°K.
Uses
Iron(III) fluroide is used in ceramics manufacturing. It is used as a catalyst for certain cross coupling reactions. Further, it is involved in the chemoselective addition of cyanide to aldehyde to prepare cyanohydrins.
Uses
As catalyst in organic reactions.
Preparation
This can be prepared by the action of fluorine on the metal,
iron(II), or iron(III) chloride or by dehydration of the hydrate (obtained from aqueous
solution) by heating in a current of hydrogen fluoride. A convenient laboratory preparation involves the reaction of hydrogen fluoride with anhydrous iron(III) chloride
at room temperature :
FeCl3+3HF→ FeF3+3HCl
When crystallized from aqueous solution (iron(III) "hydroxide" and aqueous hydrofluoric acid) it forms the pale pink 4-hydrate (room temperature evaporation) and the pink 3-hydrate (evaporation by heating).
General Description
IRON (II) FLUORIDE is a green crystalline solid. IRON (II) FLUORIDE is slightly soluble in water. The primary hazard is the threat to the environment. Immediate steps should be taken to limit its spread to the environment. IRON (II) FLUORIDE is used in ceramics.
Air & Water Reactions
Slightly soluble in water forming acidic solutions.
Reactivity Profile
Acidic salts, such as IRON (II) FLUORIDE, are generally soluble in water. The resulting solutions contain moderate concentrations of hydrogen ions and have pH's of less than 7.0. They react as acids to neutralize bases. These neutralizations generate heat, but less or far less than is generated by neutralization of inorganic acids, inorganic oxoacids, and carboxylic acid. They usually do not react as either oxidizing agents or reducing agents but such behavior is not impossible. IRON (II) FLUORIDE is used to catalyze organic reactions.
Health Hazard
INHALATION: Inorganic fluorides are generally irritating. INGESTION: Ingestion of iron compounds can cause: lethargy, retching, vomiting, tarry stools, fast and weak pulse, low blood pressure, and coma.
Fire Hazard
Behavior in Fire: May give off fumes or vapors of fluorides; hydrofluoric acid.
Battery Materials
Among various next-generation candidates, iron trifluoride (FeF3) has drawn significant attention as a conversion-type positive electrode that operates within 1.0 – 4.0 V and delivers a high theoretical specific capacity of 712 mAh g−1 at an average voltage of 2.74 V versus Li+/Li4-6. The iron(III) fluoride positive electrode also offers advantages of low cost, high abundance, and environmental compatibility, making it a promising candidate for large-scale energy storage applications
[1].
Safety Profile
Moderately toxic by
intraperitoneal route. Mutation data
reported. When heated to decomposition it
emits toxic fumes of F-. See also FLUORIDES.
References
[1] Jiang, Z., Luo, S., Wang, P., Peng, J., Hao, M., Chu, F., Lei, J., Ferreira, P., Wu, F. (2026). Interfacial anionic competition-driven electrochemical evolution in FeF3 conversion electrodes. Nature Communications.
https://doi.org/10.1038/s41467-026-72471-z
