Oxidation State +5 (PX5)
| Chemical formula | CAS number | Melting point | Boiling point | P–Xax bond length | P–Xeq bond length | Xeq–P–Xeq bond angle | Xax–P–Xeq bond angle |
|---|---|---|---|---|---|---|---|
| PF5 | -93.7°C | -84.5°C | 153 pm | 158 pm | 120° | 90° | |
| PCl5 | 167°C | 160°C | 202 pm | 214 pm | 120° | 90° | |
| PBr5 | ~106°C d | ||||||
| PBr7 | |||||||
| PI5 | See Note 1. | ||||||
In the gas phase the phosphorus pentahalides have trigonal bipyramidal molecular geometry as explained by VSEPR theory.
Phosphorus pentafluoride is a relatively inert gas, notable as a mild Lewis acid and a fluoride ion acceptor. It is a fluxional molecule in which the axial (ax) and equatorial (eq) fluorine atoms interchange positions by the Berry pseudorotation mechanism.
Phosphorus pentachloride, phosphorus pentabromide, and phosphorus heptabromide are ionic in the solid and liquid states; PCl5 is formulated as PCl4+PCl6–, but in contrast, PBr5 is formulated as PBr4+ Br−, and PBr7 is formulated as PBr4+ Br3-. They are widely used as chlorinating and brominating agents in organic chemistry.
Read more about this topic: Phosphorus Halide
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