Diphosphane

Structural formula
General
Surname	Diphosphane
other names	Diphosphorus dihydride Diphosphine Diphosphene
Molecular formula	P 2 H 4
External identifiers / databases
CAS number 13445-50-6 PubChem 139283 Wikidata Q2442174
properties
Molar mass	65.98 g mol −1
Melting point	−99 ° C
boiling point	52 ° C
solubility	bad in water
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Diphosphine is a phosphane and is a binary phosphorus hydride with the empirical formula P ₂ H ₄ . Above −99 ° C it is a colorless liquid. It is not stable in air, but ignites spontaneously. In addition, it disproportionates to PH ₃ and higher phosphanes at temperatures above −30 ° C. It is a common impurity in commercially available monophosphine .

Manufacturing

Diphosphane can be obtained by hydrolysis of calcium monophosphide (Ca ₂ P ₂ ):

${\displaystyle \mathrm {Ca_{2}P_{2}+4\ H_{2}O\longrightarrow 2\ Ca(OH)_{2}+P_{2}H_{4}} }$

The hydrolysis of 400 g Ca ₂ P ₂ at −30 ° C yields about 20 g P ₂ H ₄ . Other phosphines are produced as impurities.

Properties and reactions

Diphosphane is a colorless liquid which can spontaneously ignite in the air, which decomposes in the presence of traces of acid, at temperatures above −10 ° C (especially when exposed to light) and on rough surfaces. It is miscible with carbon disulfide , pyridine , hydrocarbons, ethers, diethylene glycol monomethyl ether , diethylene glycol dimethyl ether , hexamethylphosphoric acid triamide, and soluble in methanol. It is in the Gauche conformation , with a PP distance of 2.219 Angstroms . The ¹ H NMR spectrum consists of 32 lines from the A ₂ XX'A ' ₂ split.

The reaction of diphosphine with butyllithium leads to various condensed polyphosphines.

Organic diphosphines

Various organic derivatives of diphosphane are known. Some or all of the hydrogen atoms are substituted by organyl radicals. They are synthesized by reductive coupling z. B. from chlorodiphenylphosphine :

${\displaystyle \mathrm {2\ ClPPh_{2}+2\ Na\longrightarrow Ph_{2}PPPh_{2}+2\ NaCl} }$

The methyl derivative P ₂ Me ₄ is obtained by reacting thiophosphoryl trichloride with methyl magnesium bromide .

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1. ↑ ^{a b c} Entry on phosphanes. In: Römpp Online . Georg Thieme Verlag, accessed on July 26, 2013.
2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
3. ^ ^{A b} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , p. 745.
4. ↑ Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 516.
5. ^ Marianne Baudler, Klaus Glinka: Monocyclic and polycyclic phosphines . In: Chem Rev.. . 93, No. 4, 1993, pp. 1623-1667. doi : 10.1021 / cr00020a010 .
6. ^ Peter Paetzold: Chemistry . de Gruyter, Berlin 2009, ISBN 978-3-11-020268-7 , p. 658 .
7. ↑ David Crich (Ed.): Reagents for Radical and Radical Ion Chemistry . Wiley, J, New York, NY 2008, ISBN 978-0-470-06536-5 .