FeF3

FeF3, or iron(III) fluoride, is an inorganic compound in which iron is in the +3 oxidation state and is coordinated by fluoride ligands. It is typically encountered as a crystalline solid with limited water solubility and is less common than iron(II) fluoride (FeF2).

Preparation methods for FeF3 include direct fluorination of iron metal with fluorine gas at elevated temperatures, giving FeF3. It can also be formed by oxidizing iron(II) fluoride with fluorine, or by treating iron oxides with hydrofluoric acid under conditions that promote fluoride formation followed by dehydration.

FeF3 is a stable, dense solid with low solubility in water. It readily hydrolyzes in the presence of moisture to form iron oxyfluoride species and hydrogen fluoride. The compound exists in more than one crystalline form, reflecting different packing arrangements of the iron-fluoride network.

In addition to its basic inorganic chemistry, FeF3 has been studied for practical applications. It serves as a precursor for preparing other iron fluorides and has been explored as a fluorinating agent in organic synthesis. More recently, FeF3 has attracted interest as a potential cathode material for lithium-ion batteries because of its high theoretical capacity, though achieving good practical performance requires specialized synthesis and processing.

Safety and handling notes apply to all fluoride compounds. Iron(III) fluoride is toxic in sufficient quantities, and fluoride species can release hydrogen fluoride upon hydrolysis. Handling should be conducted with appropriate protective equipment, in dry conditions, and with proper waste management to minimize exposure and environmental impact.