Trisulfur#Radical anion

In terms of structure and bonding {{chem2|S3}} and ozone ({{chem2|O3}}) are similar. Both adopt bent structures and are diamagnetic. Although represented with S=S double bonds, the bonding situation is more complex.{{Greenwood&Earnshaw|pages = 645–662}}

The S–S distances are equivalent and are {{val|191.70|0.01|ul=pm}}, and with an angle at the central atom of {{val|117.36|.006|u=°}}.{{cite journal |title=The rotational spectrum and geometrical structure of thiozone, S₃ |volume=126 |issue=13 |pages=4096–4097 |doi=10.1021/ja049645f |pmid=15053585 |date=11 March 2004 |journal=Journal of the American Chemical Society |first1=Michael C. |last1=McCarthy |first2=Sven |last2=Thorwirth |first3=Carl A. |last3=Gottlieb |last4=Patrick |first4=Thaddeus |bibcode=2004JAChS.126.4096M}} However, cyclic {{chem2|S3}}, where the sulfur atoms are arranged in an equilateral triangle with three single bonds (similar to cyclic ozone and cyclopropane), is calculated to be lower in energy than the bent structure experimentally observed.{{cite journal |url=http://www.roaldhoffmann.com/pn/modules/Downloads/docs/513s.pdf |title=Transition metal complexes of cyclic and open ozone and thiozone |date=1 June 2005 |journal=Journal of the American Chemical Society |volume=127 |issue=4 |pages=1278–1285|doi=10.1021/ja044809d |first1=Beate |last1=Flemmig |first2=Peter T. |last2=Wolczanski |first3=Roald |last3=Hoffmann |pmid=15669867|bibcode=2005JAChS.127.1278F }} A similar structure has been predicted for ozone, but has not been observed.

The name thiozone was invented by Hugo Erdmann in 1908 who hypothesized that {{chem2|S3}} comprises a large proportion of liquid sulfur.{{cite journal |title=Ueber Thiozonide, ein Beitrag zur Kenntniss des Schwefels und seiner ringförmigen Verbindungen |trans-title=On thiozonide, an article on the knowledge of sulfur and its ring-forming compounds |journal=Justus Liebigs Annalen der Chemie |first=Hugo |last=Erdmann |pages=133–173 |issue=2 |volume=362 |year=1908 |doi=10.1002/jlac.19083620202|url=https://zenodo.org/record/1427577}} However its existence was unproven until the experiments of J. Berkowitz in 1964. Using mass spectrometry, he showed that sulfur vapour contains the {{chem2|S3}} molecule. Above {{convert|1200|°C}} {{chem2|S3}} is the second most common molecule after {{chem2|S2}} in gaseous sulfur.{{cite journal |journal=Chemical Reviews |volume=76 |issue=3 |pages=367–388 |title=Elemental sulfur |date=March 1975 |first=Beat |last=Meyer |url=http://www.gps.caltech.edu/~vijay/Papers/Chemistry/Meyer-76.pdf |doi=10.1021/cr60301a003}} In liquid sulfur the molecule is not common until the temperature is high, such as {{convert|500|°C}}. However, small molecules like this contribute to most of the reactivity of liquid sulfur. {{chem2|S3}} has an absorption peak of {{val|425|u=nm}} (violet) with a tail extending into blue light.

{{chem2|S3}} can also be generated by photolysis of {{chem2|S3Cl2}} embedded in a glass or matrix of solid noble gas.

{{chem2|S3}} occurs naturally on Io in volcanic emissions. {{chem2|S3}} is also likely to appear in the atmosphere of Venus at heights of 20 to 30 km, where it is in thermal equilibrium with {{chem2|S2}} and {{chem2|S4}}.{{cite book |title=Physics and Chemistry of the Solar System |first=John S. |last=Lewis |year=2004 |publisher=Academic Press |url=https://books.google.com/books?id=uY79k7Nx-egC|isbn=978-0-12-446744-6}}{{rp|546}} The reddish colour of Venus' atmosphere at lower levels is likely to be due to {{chem2|S3}}.{{rp|539}}

{{chem2|S3}} reacts with carbon monoxide to make carbonyl sulfide and {{chem2|S2}}.

Formation of compounds with a defined number of sulfur atoms is possible:

:{{chem2|S3 + S2O → S5O}} (cyclic){{cite journal |title=The thermal decomposition of S₂O forming SO₂, S₃, S₄ and S₅O — an ab initio MO study |doi=10.1002/chin.200444022|volume=35 |issue=44 |date=2 November 2004 |journal=ChemInform|last1=Steudel |first1=Ralf |last2=Steudel |first2=Yana}}

Image:Lazurite.jpg contains {{chem2|S3-}}.]]

Although {{chem2|S3}} is elusive under ordinary conditions, the intensely blue radical anion {{chem2|S3−}} is abundant.{{cite journal | first1 = Tristram | last1 = Chivers | first2 = Philip J. W. | last2 = Elder | title = Ubiquitous trisulfur radical anion: fundamentals and applications in materials science, electrochemistry, analytical chemistry and geochemistry | journal = Chem. Soc. Rev. | year = 2013 | volume = 42 | issue = 14 | pages = 5996–6005 | doi = 10.1039/C3CS60119F | pmid = 23628896}} The anion is sometimes called thiozonide,{{cite journal |journal=Zeitschrift für Physikalische Chemie |volume=222 |issue=1 |pages=163–176 |title=Electronic states of the ultramarine chromophore S{{sup sub|–|3}} |year=2008 |doi=10.1524/zpch.2008.222.1.163 |first1=Roberto |last1=Linguerri |first2=Najia |last2=Komiha |first3=Jürgen |last3=Fabian |first4=Pavel |last4=Rosmus|s2cid=95495454}} by analogy with the ozonide anion, {{chem2|O3-}}, to which it is valence isoelectronic. The preferred IUPAC name is trisulfanidylo. The gemstone lapis lazuli and the mineral lazurite (from which the pigment ultramarine is derived) contain {{chem2|S3-}}. International Klein Blue, developed by Yves Klein, also contains the {{chem2|S3-}} radical anion.{{cite journal |journal=Science |date=25 February 2011 |volume=331 |issue=6020 |pages=1018–1019 |doi=10.1126/science.1202468 |title=Sulfur surprises in deep geological fluids |first=Craig E. |last=Manning |bibcode = 2011Sci...331.1018M |pmid=21350156 |s2cid=206532249}} The blue colour is due to the C²A₂ transition to the X²B₁ electronic state in the ion, causing a strong absorption band at 610–{{val|620|ul=nm}} or {{val|2.07|ul=eV}} (in the orange region of the visible spectrum).{{cite book |title=Elemental Sulfur and Sulfur-Rich Compounds |volume=2 |first=Ralf |last=Steudel |page=16 |url=https://books.google.com/books?id=QvshwPCy1DkC |year= 2003|chapter=Cluster anions {{chem|S|n|-}} and {{chem|S|n|2-}} |publisher=Springer |isbn=978-3-540-40378-4}} The Raman frequency is {{val|523|ul=cm-1}} and another infrared absorption is at {{val|580|u=cm-1}}.

The {{chem2|S3-}} ion has been shown to be stable in aqueous solution under a pressure of {{convert|0.5|GPa|abbr=on|lk=on}}, and is expected to occur naturally at depth in the Earth's crust where subduction or high pressure metamorphism occurs.{{cite journal |journal=Science |date=25 February 2011 |volume=331 |issue=6020 |pages=1052–1054 |doi=10.1126/science.1199911 |title=The S{{sup sub|–|3}} ion is stable in geological fluids at elevated temperatures and pressures |first1=Gleb S. |last1=Pokrovski |first2=Leonid S. |last2=Dubrovinsky |bibcode=2011Sci...331.1052P |pmid=21350173 |s2cid=206530875}} This ion is probably important in movement of copper and gold in hydrothermal fluids.{{cite journal |journal=Proceedings of the National Academy of Sciences |title=Sulfur radical species form gold deposits on Earth |date=3 November 2015 |orig-date=12 October 2015 |volume=112 |issue=44 |pages=13484–13489 |vauthors=Pokrovsky GS, Kokh MA, Guillaume D, etal |doi=10.1073/pnas.1506378112 |pmid=26460040 |pmc=4640777 |bibcode=2015PNAS..11213484P |doi-access=free}}

Lithium hexasulfide (which contains {{chem2|S6-}}, another polysulfide radical anion) with tetramethylenediamine solvation dissociates acetone and related donor solvents to {{chem2|S3-}}.{{cite book |url=https://books.google.com/books?id=NapLdl5WAcYC |title=Inorganic Rings and Polymers of the p-Block Elements: From Fundamentals to Applications |pages=295–296 |year=2009 |publisher=Royal Society of Chemistry |first1=Tristram |last1=Chivers |first2=Ian |last2=Manners |isbn=978-1-84755-906-7}}

The {{chem2|S3-}} radical anion was also made by reducing gaseous sulfur with {{chem2|Zn(2+)}} in a matrix. The material is strongly blue-coloured when dry and changes colour to green and yellow in the presence of trace amounts of water.{{cite journal |title=Sensor material based on occluded trisulfur anionic radicals for convenient detection of trace amounts of water molecules |first1=Qian |last1=Gao |first2=Yang |last2=Xiu |first3=Guo-dong |last3=Li |first4=Jie-sheng |last4=Chen |journal=Journal of Materials Chemistry |year=2010 |volume=20 |pages=3307–3312 |issue=16 |doi=10.1039/B925233A}} Another way to make it is with polysulfide dissolved in hexamethylphosphoramide where it gives a blue colour.{{cite journal |title=Characterization of the trisulfur radical anion {{chem|S|3|-}} in blue solutions of alkali polysulfides in hexamethylphosphoramide |first1=T. |last1=Chivers |first2=I. |last2=Drummond |journal=Inorganic Chemistry |issue=10 |pages=2525–2527 |doi=10.1021/ic50116a047 |date=October 1972 |volume=11}}

Other methods of production of {{chem2|S3-}} include reacting sulfur with partially hydroxylated magnesium oxide at 400 °C.{{cite journal | first1 = J. H. | last1 = Lunsford | first2 = D. P. | last2 = Johnson | title = Electron paramagnetic resonance study of S{{sup sub|–|3}} formed on magnesium oxide | journal = The Journal of Chemical Physics | year = 1973 | volume = 58 | issue = 5 | pages = 2079–2083 | doi = 10.1063/1.1679473}}

Raman spectroscopy can be used to identify {{chem2|S3-}}, and it can be used non-destructively in paintings. The bands are {{val|549|u=cm-1}} for symmetric stretch, {{val|585|u=cm-1}} for asymmetric stretch, and {{val|259|u=cm-1}} for bending.{{cite web |url=http://www.icors2010.org/abstractfiles/ICORS20100099.6625VER.2.pdf |title=Raman microscopy of diverse samples of lapis lazuli at multiple excitation wavelengths |first1=Richard R. |last1=Hark |first2=Robin J. H. |last2=Clark |url-status=dead |archive-url=https://web.archive.org/web/20110726170002/http://www.icors2010.org/abstractfiles/ICORS20100099.6625VER.2.pdf |archive-date=2011-07-26}} Natural materials can also contain {{chem2|S2-}} which has an optical absorption at {{val|390|u=nm}} and Raman band at {{val|590|u=cm-1}}.

The trisulfide ion, {{chem2|S3(2-)}} is part of the polysulfide series. The sulfur chain is bent at an angle of 107.88°. Strontium trisulfide ({{chem2|SrS3}}) has a S–S bond length of {{val|205|u=pm}}. The bonds are single. It is isoelectronic to sulfur dichloride.

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Category:Allotropes of sulfur

Category:Homonuclear triatomic molecules

Category:Gases with color