Phosphorus sulfides

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Template:Short description Phosphorus sulfides comprise a family of inorganic compounds containing only phosphorus and sulfur. These compounds have the formula Template:Chem2 with n ≤ 10. Two are of commercial significance, phosphorus pentasulfide (Template:Chem2), which is made on a kiloton scale for the production of other organosulfur compounds, and phosphorus sesquisulfide (Template:Chem2), used in the production of "strike anywhere matches".

There are several other phosphorus sulfides in addition to Template:Chem2 and Template:Chem2. Six of these phosphorus sulfides exist as isomers: Template:Chem2. These isomers are distinguished by Greek letter prefixes. The prefix is based on the order of the discovery of the isomers, not their structure.[1] All known molecular phosphorus sulfides contain a tetrahedral array of four phosphorus atoms.[2] Template:Chem2 is also known but is unstable above −30 °C.[3]

Phosphorus monosulfide monomer, PS, is highly unstable and only exists at elevated temperatures. Its bond, worth about 55 kcal/mol, is about 2.4 angstroms long.[4]

File:LowResP-Srings.png
Phosphorus sulfides that exist in isomeric forms

Preparation

The main method for preparing these compounds is thermolysis of mixtures of phosphorus and sulfur. The product distributions can be analyzed by 31P-NMR spectroscopy. More selective syntheses entail:

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Phosphorus sesquisulfide is prepared by treating red phosphorus with sulfur above 450 K,[7] followed by careful recrystallization with carbon disulfide and benzene. An alternative method involves the controlled fusion of white phosphorus with sulfur in an inert, non-flammable solvent.[8]

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The α- and β- forms of Template:Chem2 can be prepared by treating the corresponding isomers of Template:Chem2 with Template:Chem2:[7]

File:Preparation scheme of P4S4 isomeric forms.png

Template:Chem2 can be synthesized by the reaction of stoichiometric amounts of phosphorus, sulfur, and iodine.

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Template:Chem2 can be prepared by treating stoichiometric amounts of Template:Chem2 with sulfur in carbon disulfide solution, in the presence of light and a catalytic amount of iodine.[9] The respective product distribution is then analyzed by using 31P-NMR spectroscopy.

In particular, α-Template:Chem2 can be easily made by the photochemical reaction of Template:Chem2 with red phosphorus.[7] Note that Template:Chem2 is unstable when heated, tending to disproportionate to Template:Chem2 and Template:Chem2 before reaching its melting point.[10]

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Template:Chem2 can be made by abstracting a sulfur atom from Template:Chem2 using triphenylphosphine:[7]

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Treating α-Template:Chem2 with Template:Chem2 in Template:Chem2 also yields α-Template:Chem2.[5] The two new polymorphs δ-Template:Chem2 and ε-Template:Chem2 can be made by treating α-Template:Chem2 with Template:Chem2 in Template:Chem2.[11]

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Template:Chem2 is most conveniently made by direct union of the corresponding elements, and is one of the most easily purified binary phosphorus sulfides.[12]

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β-Template:Chem2 can be made by treating α-Template:Chem2 with Template:Chem2 in Template:Chem2, which yields a mixture between α-Template:Chem2 and β-Template:Chem2.[5]

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Template:Chem2 can be made by two methods. One method involves the heating of Template:Chem2 in excess sulfur.[7] Another method involves the heating of Template:Chem2 and Template:Chem2 in 1:2 mole ratio, where Template:Chem2 is reversibly formed:[11]

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[[Phosphorus pentasulfide|Template:Chem2]] is one of the most stable phosphorus sulfides. It is most easily made by heating white phosphorus with sulfur above 570 K in an evacuated tube.[13]

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See also

References

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  2. Holleman, A. F.; Wiberg, E. Inorganic Chemistry. Academic Press: San Diego, 2001. Template:ISBN.
  3. Heal, H. G. The Inorganic Heterocyclic Chemistry of Sulfur, Nitrogen, and Phosphorus Academic Press: London; 1980 Template:ISBN.
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  8. "Phosphorus trisulfide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 563.
  9. "Phosphorus pentasulfide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 565.
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  12. "Phosphorus heptasulfide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 566.
  13. "Diphosphorus pentasulfide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 567.

Template:Phosphorus compounds Template:Sulfides