Promethium(III) iodide is an

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

, with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

of PmI₃. It is a red

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

solid with a

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state of matter, state from solid to liquid. At the melting point the solid and liquid phase (matter), phase exist in Thermodynamic equilib ...

of 695 °C.

Preparation

Promethium(III) iodide is obtained by reacting anhydrous

hydrogen iodide Hydrogen iodide (HI) is a diatomic molecule and hydrogen halide. Aqueous solutions of HI are known as hydroiodic acid or hydriodic acid, a strong acid. Hydrogen iodide and hydroiodic acid are, however, different in that the former is a gas und ...

and

promethium(III) chloride Promethium(III) chloride is a chemical compound of promethium and chlorine with the formula PmCl3. It is an ionic, water soluble, crystalline salt that glows in the dark with a pale blue or green light due to promethium's intense radioactivity. ...

at a high temperature: : PmCl₃ + 3 HI → PmI₃ + 3 HCl From the reaction of a HI-H₂ mixture and

promethium oxide Promethium(III) oxide is a compound with the formula Pm2O3. It is the most common form of promethium Promethium is a chemical element; it has Symbol (chemistry), symbol Pm and atomic number 61. All of its isotopes are Radioactive decay, radio ...

(Pm₂O₃), promethium(III) iodide cannot be produced, and only promethium oxyiodide (PmOI) can be obtained. Promethium oxide reacts with molten

aluminum iodide Aluminium iodide is a chemical compound containing aluminium and iodine. Invariably, the name refers to a compound of the composition , formed by the reaction of aluminium and iodine or the action of on metal. The hexahydrate is obtained fr ...

at 500 °C to form promethium iodide. more complete reference required

References

Iodides Promethium compounds Lanthanide halides {{Metal-halide-stub