Bismuth(III) fluoride or bismuth trifluoride is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

bismuth Bismuth is a chemical element with the Symbol (chemistry), symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental ...

and

fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reacti ...

. The chemical formula is BiF₃. It is a grey-white powder melting at 649 °C. It occurs in nature as the rare mineral gananite.

Synthesis

Bismuth fluoride can be prepared by reacting

bismuth(III) oxide Bismuth(III) oxide is perhaps the most industrially important compound of bismuth. It is also a common starting point for bismuth chemistry. It is found naturally as the mineral bismite (monoclinic) and sphaerobismoite (tetragonal, much more rare) ...

with

hydrofluoric acid Hydrofluoric acid is a Solution (chemistry), solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly Corrosive substance, corrosive. It is used to make most fluorine-containing compounds; examples include th ...

: :Bi₂O₃ + 6 HF → 2 BiF₃ + 3 H₂O

Structure

α-BiF₃ has a cubic crystalline structure (

Pearson symbol The Pearson symbol, or Pearson notation, is used in crystallography as a means of describing a crystal structure, and was originated by W. B. Pearson. The symbol is made up of two letters followed by a number. For example: * Diamond structure ...

cF16,

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchan ...

Fm-3m, No. 225). BiF₃ is the prototype for the D0₃ structure, which is adopted by several intermetallics, including Mg₃Pr, Cu₃Sb, Fe₃Si, and AlFe₃, as well as by the hydride LaH_3.0. The unit cell is

face-centered cubic In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals. There are three main varieties of ...

with Bi at the face centers and vertices, and F at the octahedral site (mid-edges, center), and tetrahedral sites (centers of the 8 sub cubes) - thus the primitive cell contains 4 Bi and 12 F. Alternatively, with the unit cell shifted (1/4,1/4,1/4) the description can be of a fcc cell with face, edge, corner, and centers filled with F, and half (4 of) the octant centers with F, the other half with Bi (each octant type tetrahedrally arranged). The edge length of the BiF₃ cell is 0.5853 nm. β-BiF₃ has the YF₃ structure where the bismuth atom has distorted 9 coordination, tricapped trigonal prism.Wells A.F. (1984) ''Structural Inorganic Chemistry'' 5th edition Oxford Science Publications This structure is generally considered to be ionic, and contrasts with fluorides of the lighter members of group 15,

phosphorus trifluoride Phosphorus trifluoride (formula P F3), is a colorless and odorless gas. It is highly toxic and reacts slowly with water. Its main use is as a ligand in metal complexes. As a ligand, it parallels carbon monoxide in metal carbonyls, and indeed ...

, PF₃,

arsenic trifluoride Arsenic trifluoride is a chemical compound of arsenic and fluorine with the chemical formula AsF3. It is a colorless liquid which reacts readily with water. Preparation and properties It can be prepared by reacting hydrogen fluoride, HF, with ar ...

, AsF₃ and

antimony trifluoride Antimony trifluoride is the inorganic compound with the formula SbF3. Sometimes called Swarts' reagent, is one of two principal fluorides of antimony, the other being SbF5. It appears as a white solid. As well as some industrial applications, i ...

, SbF₃, where MX₃ molecular units are present in the solid.

Reactions

BiF₃ is unaffected by water and is almost insoluble. It does not form complexes readily but the following, BiF₃.3HF and BiF₄⁻ in NH₄BiF₄, are known. The addition compound H₃BiF₆ is hydrolysed by water forming BiOF.

Uses

BiF₃ has received research attention as a possible electrode material for lithium batteries and as a luminescence host material for lanthanum-doped phosphors.

References

{{fluorine compounds Bismuth compounds Fluorides Metal halides