phosphorus sulfides
{{Short description|Class of chemical compounds}}
Phosphorus sulfides comprise a family of inorganic compounds containing only phosphorus and sulfur. These compounds have the formula {{chem2|P4S_{n}|}} with n ≤ 10. Two are of commercial significance, phosphorus pentasulfide ({{chem2|P4S10}}), which is made on a kiloton scale for the production of other organosulfur compounds, and phosphorus sesquisulfide ({{chem2|P4S3}}), used in the production of "strike anywhere matches".
There are several other phosphorus sulfides in addition to {{chem2|P4S3}} and {{chem2|P4S10}}. Six of these phosphorus sulfides exist as isomers: {{chem2|P4S4, P4S5, P4S6, P4S7, P4S8, and P4S9}}. These isomers are distinguished by Greek letter prefixes. The prefix is based on the order of the discovery of the isomers, not their structure.{{cite journal|author1=Jason, M. E. |author2=Ngo, T. |author3=Rahman, S. |title = Products and Mechanisms in the Oxidation of Phosphorus by Sulfur at Low Temperature|journal = Inorg. Chem.|year = 1997|volume = 36|pages = 2633–2640|doi= 10.1021/ic9614879|issue = 12}} All known molecular phosphorus sulfides contain a tetrahedral array of four phosphorus atoms.Holleman, A. F.; Wiberg, E. Inorganic Chemistry. Academic Press: San Diego, 2001. {{ISBN|0-12-352651-5}}. {{chem2|P4S2}} is also known but is unstable above −30 °C.Heal, H. G. The Inorganic Heterocyclic Chemistry of Sulfur, Nitrogen, and Phosphorus Academic Press: London; 1980 {{ISBN|0-12-335680-6}}.
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.{{cite book|title=Sulfur in Organic and Inorganic Chemistry|volume=1|editor-first=Alexander|editor-last=Senning|year=1971|publisher=Marcel Dekker|location=New York|lccn=70-154612|isbn=0-8247-1615-9|first=Lucreţia|last=Almasi|chapter=The Sulfur–Phosphorus Bond|page=43}}
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:
- desulfurization, e.g. using triphenylphosphine and, complementarily,
- sulfidation using triphenylarsine sulfide.{{cite journal|author = Jason, M. E.|title = Transfer of Sulfur from Arsenic and Antimony Sulfides to Phosphorus Sulfides. Rational Syntheses of Several Less-Common P4Sn Species| journal = Inorg. Chem.|year = 1997|volume = 36|pages = 2641–2646|doi = 10.1021/ic9614881|issue = 12}}{{cite journal|author1=Nowottnick, H. |author2=Blachnik, R. |title = Zwei neue Phosphorsulfide (Two New Phosphorus Sulfides)|journal = Zeitschrift für anorganische und allgemeine Chemie|year = 1999|volume = 625|pages = 1966–1968|doi = 10.1002/(SICI)1521-3749(199912)625:12<1966::AID-ZAAC1966>3.0.CO;2-B|issue = 12 }}
={{chem2|P4S3}}=
Phosphorus sesquisulfide is prepared by treating red phosphorus with sulfur above 450 K,{{cite book|title = Inorganic Chemistry, 3rd Edition|chapter = Chapter 15: The group 15 elements|author1 = Catherine E. Housecroft|author2 = Alan G. Sharpe|publisher = Pearson|year = 2008|isbn = 978-0-13-175553-6|page = 484}} 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."Phosphorus trisulfide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 563.
={{chem2|P4S4}}=
The α- and β- forms of {{chem2|P4S4}} can be prepared by treating the corresponding isomers of {{chem2|P4S3I2}} with {{chem2|((CH3)3Sn)2S}}:
File:Preparation scheme of P4S4 isomeric forms.png
{{chem2|P4S3I2}} can be synthesized by the reaction of stoichiometric amounts of phosphorus, sulfur, and iodine.
={{chem2|P4S5}}=
{{chem2|P4S5}} can be prepared by treating stoichiometric amounts of {{chem2|P4S3}} with sulfur in carbon disulfide solution, in the presence of light and a catalytic amount of iodine."Phosphorus pentasulfide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 565. The respective product distribution is then analyzed by using 31P-NMR spectroscopy.
In particular, α-{{chem2|P4S5}} can be easily made by the photochemical reaction of {{chem2|P4S10}} with red phosphorus. Note that {{chem2|P4S5}} is unstable when heated, tending to disproportionate to {{chem2|P4S3}} and {{chem2|P4S7}} before reaching its melting point.{{cite book|title = Chemistry of the elements, 2nd edition|chapter = Phosphorus|author1 = A. Earnshaw|author2 = Norman Greenwood|publisher = Butterworth Heinemann|year = 2002|isbn = 0750633654|page = 508}}
={{chem2|P4S6}}=
{{chem2|P4S6}} can be made by abstracting a sulfur atom from {{chem2|P4S7}} using triphenylphosphine:
:{{chem2|P4S7 + Ph3P → P4S6 + Ph3PS}}
Treating α-{{chem2|P4S5}} with {{chem2|Ph3AsS}} in {{chem2|CS2}} also yields α-{{chem2|P4S6}}. The two new polymorphs δ-{{chem2|P4S6}} and ε-{{chem2|P4S6}} can be made by treating α-{{chem2|P4S4}} with {{chem2|Ph3SbS}} in {{chem2|CS2}}.{{cite book|title = Encyclopedia of Inorganic Chemistry, 2nd edition|chapter = Phosphorus|author1 = R. Bruce King|publisher = Wiley|year = 2005|isbn = 9780470862100|page = 3711}}
={{chem2|P4S7}}=
{{chem2|P4S7}} is most conveniently made by direct union of the corresponding elements, and is one of the most easily purified binary phosphorus sulfides."Phosphorus heptasulfide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 566.
:{{chem2|P4 + 7 S → P4S7}}
={{chem2|P4S8}}=
={{chem2|P4S9}}=
={{chem2|P4S10}}=
Phosphorus pentasulfide 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."Diphosphorus pentasulfide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 567.
:{{chem2|P4 + 10 S → P4S10}}
See also
- Diphosphorus trisulfide ({{chem2|P2S3}})