Phosphoranes

thumb|right|The structure of a typical phosphorane group. A '''phosphorane''' (IUPAC name: '''λ⁵-phosphane''') is a functional group in organophosphorus chemistry with pentavalent phosphorus. Phosphoranes have the general formula PR₅.

Phosphoranes of the type PX₅ adopt a trigonal bipyramidal molecular geometry with the two apical bonds longer than the three equatorial bonds. Hypervalent bonding is described by inclusion of non-bonding MOs, as also invoked for the closely related molecule phosphorus pentafluoride.<ref>G. L. Miessler and D. A. Tarr “Inorganic Chemistry” 3rd Ed, Pearson/Prentice Hall publisher, {{ISBN|0-13-035471-6}}.</ref>

==Examples== The parent hydride compound is the hypothetical molecule PH₅.

Pentaphenylphosphorane (Ph₅P) is stable.<ref>{{Note|Quin}} ''A Guide to Organophosphorus Chemistry'' Louis D. Quin '''2000''' John Wiley & Sons {{ISBN|0-471-31824-8}}</ref>

Pentaalkoxyphosphoranes are more common with electronegative substituents. Examples of P(OR)₅ (R = alkyl), have however been prepared by reaction of phosphites with benzene alkyl sulfenates:<ref>{{cite journal |doi=10.1021/ja00449a044 |title=Some acyclic pentaalkoxyphosphoranes |year=1977 |last1=Chang |first1=Lydia L. |last2=Denney |first2=Donald B. |last3=Denney |first3=Dorothy Z. |last4=Kazior |first4=Richard J. |journal=Journal of the American Chemical Society |volume=99 |issue=7 |pages=2293–2297 }}</ref> :{{chem2|P(OR)3 + 2 ROSC6H5 -> P(OR)5 + (SC6H5)2}}

==Wittig reagents== Phosphoranes of the type R₃P=CR₂ are more common and more important. Phosphoranes are also considered to be one of the resonance structures of ylides, these compounds feature a tetrahedral phosphorus center including a phosphorus–carbon double bond. These compounds are used as reagents in the Wittig reaction, for instance methylenetriphenylphosphorane or Ph₃P=CH₂.

== See also == * Organophosphorus chemistry * Phosphane

== References == {{Reflist}}

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Category:Organophosphanes Category:Functional groups