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| Names | |||
|---|---|---|---|
| IUPAC name Trisulfur | |||
| Other names Thiozone | |||
| Identifiers | |||
3D model (JSmol) |
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| ChEBI |
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| ChemSpider | |||
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| Properties | |||
| S3 | |||
| Molar mass | 96.198 g/mol | ||
| Appearance | Cherry-red | ||
| Structure | |||
| bent | |||
| Related compounds | |||
Related compounds | Ozone Disulfur monoxide Sulfur dioxide | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
TheS3 molecule, known astrisulfur,sulfur trimer,thiozone, ortriatomic sulfur, is a cherry-redallotrope of sulfur. It comprises about 10% of vaporised sulfur at 713 K (440 °C; 824 °F) and 1,333 Pa (10.00 mmHg; 0.1933 psi). It has been observed at cryogenic temperatures as a solid. Under ordinary conditions it converts tocyclooctasulfur.
In terms of structure and bondingS3 andozone (O3) are similar. Both adoptbent structures and arediamagnetic. Although represented with S=Sdouble bonds, the bonding situation is more complex.[1]
The S–S distances are equivalent and are191.70±0.01 pm, and with an angle at the central atom of117.36°±0.006°.[2] However, cyclicS3, where the sulfur atoms are arranged in an equilateral triangle with three single bonds (similar tocyclic ozone andcyclopropane), is calculated to be higher in energy than the bent structure experimentally observed.[3] Asimilar structure has been predicted for ozone, but has not been observed.
The name thiozone was invented byHugo Erdmann in 1908 who hypothesized thatS3 comprises a large proportion of liquid sulfur.[4] However its existence was unproven until the experiments of J. Berkowitz in 1964.[5] Usingmass spectrometry, he showed that sulfur vapour contains theS3 molecule. Above 1,200 °C (2,190 °F)S3 is the second most common molecule afterS2 in gaseous sulfur.[5] In liquid sulfur the molecule is not common until the temperature is high, such as 500 °C (932 °F). However, small molecules like this contribute to most of the reactivity of liquid sulfur.[5]S3 has an absorption peak of425 nm (violet) with a tail extending into blue light.[5]
S3 can also be generated byphotolysis ofS3Cl2 embedded in a glass or matrix of solidnoble gas.[5]
S3 occurs naturally onIo in volcanic emissions.S3 is also likely to appear in theatmosphere of Venus at heights of 20 to 30 km, where it is in thermal equilibrium withS2 andS4.[6]: 546 The reddish colour of Venus' atmosphere at lower levels is likely to be due toS3.[6]: 539
S3 reacts withcarbon monoxide to makecarbonyl sulfide andS2.
Formation of compounds with a defined number of sulfur atoms is possible:
AlthoughS3 is elusive under ordinary conditions, the intensely blueradical anionS−3 is abundant.[8] The anion is sometimes calledthiozonide,[9] by analogy with theozonide anion,O−3, to which it isvalence isoelectronic. The preferred IUPAC name is trisulfanidylo. The gemstonelapis lazuli and the minerallazurite (from which the pigmentultramarine is derived) containS−3.International Klein Blue, developed byYves Klein, also contains theS−3 radical anion.[10] The blue colour is due to the C2A2 transition to the X2B1 electronic state in the ion,[9] causing a strong absorption band at 610–620 nm or2.07 eV (in the orange region of the visible spectrum).[11] TheRaman frequency is523 cm−1 and another infrared absorption is at580 cm−1.[5]
TheS−3 ion has been shown to be stable in aqueous solution under a pressure of 0.5 GPa (73,000 psi), and is expected to occur naturally at depth in the Earth's crust where subduction or high pressure metamorphism occurs.[12] This ion is probably important in movement of copper and gold inhydrothermal fluids.[13]
Lithium hexasulfide (which containsS−6, another polysulfide radical anion) withtetramethylenediamine solvation dissociates acetone and related donor solvents toS−3.[14]
TheS−3 radical anion was also made by reducing gaseous sulfur withZn2+ 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.[15] Another way to make it is withpolysulfide dissolved inhexamethylphosphoramide where it gives a blue colour.[16]
Other methods of production ofS−3 include reacting sulfur with partially hydroxylatedmagnesium oxide at 400 °C.[17]
Raman spectroscopy can be used to identifyS−3, and it can be used non-destructively in paintings. The bands are549 cm−1 for symmetric stretch,585 cm−1 for asymmetric stretch, and259 cm−1 for bending.[18] Natural materials can also containS−2 which has an optical absorption at390 nm and Raman band at590 cm−1.[18]
Thetrisulfide ion,S2−3 is part of thepolysulfide series. The sulfur chain isbent at an angle of 107.88°.[5]Strontium trisulfide (SrS3) has a S–S bond length of205 pm.[5] The bonds are single. It isisoelectronic tosulfur dichloride.
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