Diphosphane

This article is about P₂H₄. For other uses, see diphosphines.

Diphosphane
IUPAC name Diphosphane
Systematic name Diphosphane (substitutive) Tetrahydidodiphosphorus(P—P) (additive)
Other names Diphosphine
Identifiers
CAS number	13445-50-6 N
PubChem	139283
ChemSpider	122832 N
ChEBI	CHEBI:35880 N
Jmol-3D images	Image 1
SMILES PP
InChI InChI=1S/H4P2/c1-2/h1-2H2 N Key: VURFVHCLMJOLKN-UHFFFAOYSA-N N
Properties
Molecular formula	H4P2
Molar mass	65.98 g mol−1
Exact mass	65.978823152 g mol-1
Melting point	-99 °C, 174 K, -146 °F
Boiling point	52 °C, 325 K, 126 °F
Related compounds
Related compounds	Hydrazine
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Diphosphane is an inorganic compound with the chemical formula P₂H₄. This colourless liquid is one of several binary phosphorus hydrides. It is the impurity that typically causes samples of phosphine to ignite in air. An older name is diphosphine.

Properties, preparation, reactions

Diphosphane adopts the gauche conformation (like hydrazine, less symmetrical than shown in the image) with a P-P distance of 2.219 angstroms. It is nonbasic, unstable at room temperature, and spontaneously flammable in air. It is only poorly soluble in water but dissolves in organic solvents. Its ¹H NMR spectrum consists of 32 lines resulting from an A₂XX'A'₂ splitting system.^[1]

Diphosphane is produced by the hydrolysis of calcium monophosphide, which can be described as the Ca²⁺ derivative of P₂^4-. According to an optimized procedure, hydrolysis of 400 g of CaP at -30 °C gives about 20 g of product, slightly contaminated with phosphine.

Reaction of diphosphine with butyl lithium affords a variety of condensed polyphosphine compounds.

Organic diphosphanes

A variety of organic derivatives of diphosphane are known. These species are prepared by reductive coupling, e.g. from chlorodiphenylphosphine:

ClPPh₂ + 2 Na → Ph₂PPPh₂ + 2 NaCl

The methyl compound P₂Me₄ is prepared by the reaction of thiophosphoryl chloride with methylmagnesium bromide.

See also

Diphosphene

References

1. ^ Marianne Baudler, Klaus Glinka (1993). "Monocyclic and polycyclic phosphines". Chem. Rev. 93 (4): 1623–1667. doi:10.1021/cr00020a010.