Phosphorus halides

There are three series of binary phosphorus halides, containing phosphorus in the oxidation states +5, +3 and +2. All twelve compounds have been described, in varying degrees of detail, although serious doubts have been cast on the existence of PI₅. [I. Tornieporth-Getting & T. Klapötke, "J. Chem. Soc.", "Chem. Commun." 1990, 132.doi|10.1039/C39900000132]

Oxidation state +5 (PX₅)

Phosphorus(II) halides may be prepared by passing an electric discharge through a mixture of the trihalide vapour and hydrogen gas. They are of purely academic interest at the present time. Diphosphorus tetrabromide is particularly poorly described.

Oxyhalides and thiohalides

The oxyhalides may be prepared from the corresponding trihalides by reaction with organic peroxides or ozone: they are sometimes referred to as phosphoryl halides.

The thiohalides, also known as thiophosphoryl halides may be prepared from the trihalides by reaction with elemental sulfur in an inert solvent. The corresponding selenohalides are also known.

The oxyhalides and thiohalides are significantly more electrophilic than the corresponding phosphorus(III) species, and present a significant toxic hazard.

See also

References

* [http://www.webelements.com/ WebElements]
* [http://webbook.nist.gov/chemistry/ NIST Standard Reference Database]
* N. N. Greenwood & A. Earnshaw, "Chemistry of the Elements" (2nd ed.), Butterworth-Heinemann, Oxford, 1997.