Overview
Antimony trifluoride is an inorganic compound with the formula SbF3. Often called antimony(III) fluoride or Swart's reagent, it features antimony in the +3 oxidation state bonded to fluoride ligands. The name antimony(III) fluoride and the historic designation reflect its long use in laboratory and small-scale industrial synthesis.
Structure and properties
In its common form SbF3 is a white to pale crystalline solid. The antimony center formally carries a +3 oxidation state and the molecule can be described as having a lone pair on antimony that gives a trigonal pyramidal geometry in discrete molecules; in the solid state, extended structures with bridging fluorides are observed. It is sensitive to moisture and undergoes hydrolysis to give oxyfluoride species. Basic chemical information about the element is available at antimony, while fluoride chemistry is discussed at fluoride.
Preparation and reactions
Antimony trifluoride is prepared and handled by inorganic fluorination methods. Typical laboratory routes include treating antimony(III) chloride or antimony oxides with hydrogen fluoride or other fluorinating agents under controlled conditions. SbF3 acts as a source of nucleophilic fluoride in some reactions and can form complex fluoride species with strong Lewis acids. It is also subject to hydrolysis and must be kept dry to avoid formation of corrosive by-products.
Uses and applications
The compound is best known for its role in the Swarts reaction, a halogen-exchange process used historically to convert alkyl chlorides or bromides into the corresponding fluorides in organic synthesis. For this reason it is sometimes called Swarts' reagent. Beyond organic fluorination, SbF3 is used as an intermediate in the preparation of other antimony fluorides and in specialized inorganic syntheses. For a broader view of its applications see related reagent information.
Safety and notable distinctions
Antimony compounds are potentially toxic and SbF3 should be handled with appropriate precautions: gloves, eye protection and fume hood. Contact with moisture can release acidic or corrosive fluoride-containing species and may pose inhalation or skin hazards. SbF3 differs from antimony pentafluoride (SbF5), which is a much stronger Lewis acid and a component of superacid systems; these differences reflect the distinct oxidation states and reactivity of antimony fluorides. Additional chemical risks and recommended handling practices are covered in standard safety sources and material safety data sheets (safety information).