Diphosphane, or diphosphine, is an
inorganic compound
An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bondsthat is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''.
Inorgan ...
with the chemical formula . This colourless liquid is one of several binary phosphorus hydrides. It is the impurity that typically causes samples of
phosphine
Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...
to ignite in air.
Properties, preparation, reactions
Diphosphane adopts the
gauche conformation (like
hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly hazardous unless handled in solution as, for example, hydraz ...
, less symmetrical than shown in the image) with a P−P distance of 2.219
angstrom
The angstrom (; ) is a unit of length equal to m; that is, one ten-billionth of a metre, a hundred-millionth of a centimetre, 0.1 nanometre, or 100 picometres. The unit is named after the Swedish physicist Anders Jonas Ångström (1814–18 ...
s. 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 A
2XX'A'
2 splitting system.
Diphosphane is produced by the hydrolysis of
calcium monophosphide
Calcium monophosphide is the inorganic compound with the formula CaP. It is sometimes also known as "calcium phosphide", which also describes a different compound with composition Ca3P2. Calcium monophosphide is a black solid.
Structure and prop ...
, which can be described as the Ca
2+ derivative of . According to an optimized procedure, hydrolysis of 400 g of CaP at −30 °C gives about 20 g of product, slightly contaminated with
phosphine
Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...
.
Reaction of diphosphane with
butyllithium Butyllithium may refer to one of 5 isomeric organolithium reagents of which 3 are commonly used in chemical synthesis:
* ''n''-Butyllithium, abbreviated BuLi or nBuLi
* ''sec''-Butyllithium, abbreviated ''sec''-BuLi or sBuLi, has 2 stereoisomers, ...
affords a variety of condensed polyphosphine compounds.
Organic diphosphanes
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 to
chiral inversion.
The central bond is weak, and easily adds substituents.
The simplest synthesis method heats a phosphorus halide and a phosphane:
:
Alkali metals can replace the hydrogen in that reaction (i.e., a dialkyl
phosphide
In chemistry, a phosphide is a compound containing the ion or its equivalent. Many different phosphides are known, with widely differing structures. Most commonly encountered on the binary phosphides, i.e. those materials consisting only of pho ...
), and in some rare cases a dialkylamine can replace the halide. Symmetric diphosphanes are easily prepared by reductive coupling, e.g.
tetraphenyldiphosphine
Tetraphenyldiphosphine is the organophosphorus compound with the formula Ph2sub>2, where Ph = phenyl (C6H5). It is a white, air-sensitive solid that dissolves in nonpolar solvents. It is a centrosymmetric molecule with a P-P bond of 2.2592 Å ...
from
chlorodiphenylphosphine
Chlorodiphenylphosphine is an organophosphorus compound with the formula (C6H5)2PCl, abbreviated Ph2PCl. It is a colourless oily liquid with a pungent odor that is often described as being garlic-like and detectable even in the ppb range. It is ...
:
:
Ultraviolet radiation decomposes
mercury(II) dialkylphosphides to the metal and a dialkylphosphane.
The methyl compound is prepared by the reduction of , which is produced by methylation of
thiophosphoryl chloride
Thiophosphoryl chloride is an inorganic compound with the chemical formula .Spilling, C. D. "Thiophosphoryl Chloride" in Encyclopedia of Reagents for Organic Synthesis John Wiley & Sons, Weinheim, 2001 . Article Online Posting Date: April 15, 2001 ...
with methylmagnesium bromide.
See also
*
Pnictogen hydride
Pnictogen hydrides or hydrogen pnictides are binary compounds of hydrogen with pnictogen ( or ; from "to choke" and -gen, "generator") atoms (elements of group 15: nitrogen, phosphorus, arsenic, antimony, bismuth, and moscovium) covalently bonded ...
References
Phosphorus hydrides
Foul-smelling chemicals
Pyrophoric materials
{{Hydrides by group