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| Names | |||
|---|---|---|---|
| IUPAC name Diphosphane | |||
| Systematic IUPAC name Diphosphane (substitutive) Tetrahydridodiphosphorus(P—P) (additive) | |||
| Other names Diphosphine | |||
| Identifiers | |||
3D model (JSmol) | |||
| ChEBI | |||
| ChemSpider |
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| Properties | |||
| P2H4 | |||
| Melting point | −99 °C (−146 °F; 174 K) | ||
| Boiling point | 63.5 °C (146.3 °F; 336.6 K) (Extrapolated, decomposes) | ||
| Related compounds | |||
Otheranions | ammonia hydrazine triazane | ||
Othercations | diphosphines | ||
Related BinaryPhosphorus halides | diphosphorus tetrafluoride diphosphorus tetrachloride diphosphorus tetrabromide diphosphorus tetraiodide | ||
Related compounds | phosphane triphosphane diphosphene diphosphenes | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Diphosphane, ordiphosphine, is aninorganic compound with the chemical formulaP2H4. This colourless liquid is one of several binary phosphorus hydrides. It is the impurity that typically causes samples ofphosphine to ignite in air.
Diphosphane adopts thegauche conformation (likehydrazine, less symmetrical than shown in the image) with a P−P distance of 2.219angstroms. It is nonbasic, unstable at room temperature, andspontaneously flammable in air. It is only poorly soluble in water but dissolves in organic solvents. Its1H NMR spectrum consists of 32 lines resulting from an A2XX'A'2 splitting system.[1]
Diphosphane is produced by the hydrolysis ofcalcium monophosphide, which can be described as the Ca2+ derivative ofP4−2. According to an optimized procedure, hydrolysis of 400 g of CaP at −30 °C gives about 20 g of product, slightly contaminated withphosphine.[citation needed]
Reaction of diphosphane withbutyllithium affords a variety of condensed polyphosphine compounds.
A variety of organic derivatives of diphosphane are known, but asymmetric diphosphanes are only stable at cryogenic temperatures. Otherwise, the substituents facily redistribute on the phosphorus centers to give a mixture of products. On the other hand, there appears to be a substantial barrier tochiral inversion.[2]
The central bond is weak, and easily adds substituents.[3]
The simplest synthesis method heats a phosphorus halide and a phosphane:
Alkali metals can replace the hydrogen in that reaction (i.e., a dialkylphosphide), and in some rare cases a dialkylamine can replace the halide. Symmetric diphosphanes are easily prepared by reductive coupling, e.g.tetraphenyldiphosphine fromchlorodiphenylphosphine:
Ultraviolet radiation decomposesmercury(II) dialkylphosphides to the metal and a dialkylphosphane.[4]
The methyl compoundP2Me4 is prepared by the reduction ofMe2P(S)−P(S)Me2, which is produced by methylation ofthiophosphoryl chloride with methylmagnesium bromide.[5]
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