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| Names | |
|---|---|
| IUPAC name Phosphorus pentafluoride | |
| Other names
Phosphorus(V) fluoride Pentafluoridophosphorus Pentafluorophosphorane | |
| Identifiers | |
| CAS Number | |
| ECHA InfoCard | 100.028.730 
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| CompTox Dashboard (EPA) | |
| Properties | |
| Chemical formula | PF5 |
| Molar mass | 125.97 g/mol |
| Appearance | colourless gas |
| Melting point | −93.78 °C (179.4 K) |
| Boiling point | −84.5 °C (188.7 K) |
| Solubility in water | hydrolysis |
| Structure | |
| Molecular shape | trigonal bipyramidal |
| Dipole moment | 0 D |
| Hazards | |
| Flash point | Non-flammable |
| Related compounds | |
| Other anions | Phosphorus pentachloride Phosphorus pentabromide Phosphorus pentaiodide |
| Other cations | Arsenic pentafluoride Antimony pentafluoride Bismuth pentafluoride |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references | |
Phosphorus pentafluoride, PF5, is a phosphorus halide. It's a colourless gas at room temperature and pressure.
Structure
Single-crystal X-ray studies indicate PF5 molecule has two distinct P−F bonds (axial and equatorial): P−Fax = 158.0 pm and P−Feq = 152.2 pm. Gas-phase electron diffraction analysis gives similar values: P−Fax = 158 pm and P−Feq = 153 pm.
F NMR spectroscopy, at temperatures as low as −100 °C fails to distinguish the axial from the equatorial fluorine environments. The apparent equivalency arises from the low barrier for pseudorotation via the Berry mechanism, by which the axial and equatorial fluorine atoms rapidly exchange positions. The apparent equivalency of the F centers in PF5 was first noted by Gutowsky.. The explanation was first described by R. Stephen Berry, after whom the Berry mechanism is named. Berry pseudorotation influences theF NMR spectrum of PF5 since NMR spectroscopy operates on a millisecond timescale. Electron diffraction and X-ray crystallography do not detect this effect as their timescales are significantly shorter than for NMR spectroscopy.
References
 | This article has an unclear citation style. The references used may be made clearer with a different or consistent style of citation and footnoting. (September 2007) (Learn how and when to remove this message) |
- Gutowsky, H. S.; McCall, D. W.; Slichter, C. P. "Nuclear Magnetic Resonance Multiplets in Liquids" Journal of Chemical Physics 1953, volume 21, 279.
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
External links
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