Antimony triiodide is the

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 ...

with the formula Sb I₃. This ruby-red solid is the only characterized "binary" iodide of

antimony Antimony is a chemical element; it has chemical symbol, symbol Sb () and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (). Antimony compounds have been known since ancient t ...

, i.e. the sole compound isolated with the formula Sb_xI_y. It contains antimony in its +3 oxidation state. Like many iodides of the heavier

main group element In chemistry and atomic physics, the main group is the group (periodic table), group of chemical element, elements (sometimes called the representative elements) whose lightest members are represented by helium, lithium, beryllium, boron, carbon ...

s, its structure depends on the phase. Gaseous SbI₃ is a molecular, pyramidal species as anticipated by

VSEPR theory Valence shell electron pair repulsion (VSEPR) theory ( , ) is a conceptual model, model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. It is also named the Gill ...

. In the solid state, however, the Sb center is surrounded by an

octahedron In geometry, an octahedron (: octahedra or octahedrons) is any polyhedron with eight faces. One special case is the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex. Many types of i ...

of six iodide ligands, three of which are closer and three more distant. For the related compound BiI₃, all six Bi—I distances are equal.

Production

It may be formed by the reaction of

with elemental

iodine Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...

, or the reaction of antimony trioxide with hydroiodic acid. Alternatively, it may be prepared by the interaction of antimony and iodine in boiling

benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...

or tetrachloroethane.

Uses

SbI₃ has been used as a dopant in the preparation of thermoelectric materials.

References

External links

{{Antimony compounds Iodides Metal halides Antimony(III) compounds