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| Names | |
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| IUPAC name Trimethylsulfonium | |
| Systematic IUPAC name Trimethylsulfanium | |
Other names
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3D model (JSmol) | |
| ChemSpider | |
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| Properties | |
| (CH3)3S+ | |
| Molar mass | 77.17 g·mol−1 |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Trimethylsulfonium (systematically namedtrimethylsulfanium) is anorganiccation with thechemical formula(CH3)3S+ (also written asC3H9S+).
3S%252B_in_the_BPh4-_salt_(code_HEYZAM).png)
Severalsalts of trimethylsulfonium are known.X-ray crystallography reveals that the ion hastrigonal pyramidal molecular geometry at sulfur atom, with C-S-C angles near 102° and C-S bond distance of 177picometers. Unless the counteranion is colored, all trimethylsulfonium salts are white or colorless.
| Salt | Formula | Molecular weight (g/mol) | Properties[2] |
|---|---|---|---|
| Trimethylsulfonium chloride | [(CH3)3S]+Cl− | 112.5 | Colorless crystals, decompose at 100 °C, very soluble inethanol, veryhygroscopic.[3] |
| Trimethylsulfonium bromide | [(CH3)3S]+Br− | 157 | Colorless crystals. Decomposes at 172 °C, melts in a sealed tube at 201-201 °C, reacts inneutralaqueous solution.[clarification needed][4] |
| Trimethylsulfonium iodide | [(CH3)3S]+I− | 204 | Colorless crystals, decomposes at 203-207 °C.[4][5]crystal structuremonoclinic, with theseparameters:a = 5.94 μm,b = 8.00 μm,c = 8.92 μm,β = 126°32′ 2 formulas perunit cell,[clarification needed] density = 1.958 g/cm3[6] |
| Trimethylsulfoniumtetrafluoroborate | [(CH3)3S]+[BF4]− | 163.97 | white crystalline solid[7], melting point = 205-210 °C[8] |
| Trimethylsulfonium methylsulfate | [(CH3)3S]+CH3OSO−3 | 188.27 | White solid[9], melting point = 92-94 °C[10] Crystal structureorthorhombic with these parameters:a = 12.6157 μm,b = 8.2419 μm,c = 7.540 μm cell volume 784.0 2 formulas per unit cell[clarification needed] |
Sulfonium compounds can be synthesised by treating a suitablealkyl halide with athioether. For example, the reaction ofdimethyl sulfide withiodomethane yields trimethylsulfonium iodide:
An extraoxygen atom can bond to the sulfur atom to yield thetrimethylsulfoxonium ion[(CH3)3S=O]+, where the sulfur atom istetravalent andtetracoordinated.
Glyphosateherbicide is often supplied as a trimethylsulfonium salt, referred to as trimesium.[11]
When mixed withaluminium bromide, oraluminium chloride or evenhydrogen bromide, trimethylsulfonium bromide forms anionic liquid, which melts at temperatures below standard conditions.[12]
