Phosphorus pentaiodide is a hypothetical

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 formula . The existence of this compound has been claimed intermittently since the early 1900s. The claim is disputed: "The pentaiodide does not exist (except perhaps as , but certainly not as ...)".

Claims

Phosphorus pentaiodide was reported to be a brown-black crystalline solid melting at 41 °C produced by the reaction of lithium iodide and phosphorus pentachloride in methyl iodide, however, this claim is disputed and probably generated a mixture of phosphorus triiodide and

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 ...

. Although phosphorus pentaiodide has been claimed to exist in the form of (tetraiodophosphonium iodide), experimental and theoretical data refutes this claim.

Derivatives

Unlike the elusive , the cation (tetraiodophosphonium cation) is widely known. This cation is known with the anions tetraiodoaluminate , hexafluoroarsenate , hexafluoroantimonate and tetraiodogallate .

References

Hypothetical chemical compounds Phosphorus(V) compounds Phosphorus iodides {{theoretical-chem-stub