Hexaphenylcarbodiphosphorane is the

organophosphorus compound Organophosphorus chemistry is the scientific study of the synthesis and properties of organophosphorus compounds, which are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbo ...

with the formula C(PPh₃)₂ (where Ph = C₆H₅). It is a yellow, moisture-sensitive solid. The compound is classified as an

ylide An ylide () or ylid () is a neutral dipolar molecule containing a formally negatively charged atom (usually a carbanion) directly attached to a heteroatom with a formal positive charge (usually nitrogen, phosphorus or sulfur), and in which both ...

and as such carries significant negative charge on carbon. It is isoelectronic with bis(triphenylphosphine)iminium. The P-C-P angle is 131°. The compound has attracted attention as an unusual ligand in organometallic chemistry. The pure compound has two crystalline phases: a metastable

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three Vector (geometric), vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in t ...

C2 phase that is

triboluminescent Triboluminescence is a phenomenon in which light is generated when a material is mechanically pulled apart, ripped, scratched, crushed, or rubbed (see tribology). The phenomenon is not fully understood but appears in most cases to be caused by the ...

, and an

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...

P222 form that is not. Both polymorphs are

photoluminescent Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. ph ...

, with respective peak wavelengths at 540 and 575 nm.

Preparation

The compound was originally prepared by deprotonation of the

phosphonium salt In chemistry, the term phosphonium (more obscurely: phosphinium) describes polyatomic cations with the chemical formula (where R is a hydrogen or an alkyl, aryl, organyl or halogen group). These cations have tetrahedral structures. The salt ...

C(PPh₃)₂r using potassium. An improved procedure entails production of the same double phosphonium salt from methylene bromide. The double deprotonation is effected with potassium amide.{{cite journal , doi=10.1016/j.ica.2017.04.018, title=Synthetic and NMR Studies on Hexaphenylcarbodiphosphorane (Ph₃P=C=PPh₃), year=2017, last1=Gruber, first1=Marco, last2=Bauer, first2=Walter, last3=Maid, first3=Harald, last4=Schöll, first4=Kilian, last5=Tykwinski, first5=Rik R., journal=Inorganica Chimica Acta, volume=468, pages=152–158

Related compounds

* Methylenetriphenylphosphorane (CH₂=PPh₃), the parent Wittig reagent

References

Organophosphorus compounds Ligands