Phosphorus pentaiodide

Phosphorus pentaiodide is an inorganic compound with formula PI₅. The existence of this compound has been claimed intermittently since the early 1900s.[1] The claim is disputed: "The pentaiodide does not exist (except perhaps as PI₃·I₂, but certainly not as PI⁺
₄I⁻
...)".[2]

References

1. Walker and Johnson, J. Chem. Soc. 87, 1595 (1905).
2. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.