Trimethylsulfonium

Trimethylsulfonium
Names
	Preferred IUPAC name Trimethylsulfanium
	Other names Trimesium
Identifiers
CAS Number	676-84-6 ;
3D model (JSmol)	Interactive image;
ChemSpider	1115;
PubChem CID	1147;
UNII	8U5M0SJV65 ;
	InChI InChI=1S/C3H9S/c1-4(2)3/h1-3H3/q+1 Key: NRZWQKGABZFFKE-UHFFFAOYSA-N;
	SMILES C[S+](C)C;
Properties
Chemical formula	C3H9S+
Molar mass	77.17 g/mol
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	Infobox references

Trimethylsulfonium (systematically named trimethylsulfanium and trimethylsulfur(1+)) is an organic cation with the chemical formula (CH₃)₃S⁺ (also written as C
₃H
₉S⁺
).

Compounds[]

Structure of (CH₃)₃S⁺ as its tetraphenylborate salt.^[1]

Several salts of trimethylsulfonium are known. X-ray crystallography reveals that the sulfur is pyramidal, with C-S-C angles near 102° and C-S bond distance of 177 picometers. Unless the anion 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 in ethanol, very hygroscopic.^[3]
Trimethylsulfonium bromide	[(CH₃)₃S]Br	157	Colorless crystals from H₂O. Decomposes at 172 °C, melts in a sealed tube at 201-201 °C, reacts in neutral aqueous solution.^[4]
Trimethylsulfonium iodide	[(CH₃)₃S]I	204	Colorless crystals from ethanol, decomposes at 203-207 °C.^[4]^[5] crystal structure monoclinic a=5.94 b=8.00 c=8.92 μm β=126°32′ 2 formulas per unit cell density=1.958^[6]
Trimethylsulfonium tetrafluoroborate	[(CH₃)₃S]BF₄	163.97	mp 205-210°^[7]
Trimethylsulfonium methylsulfate	[(CH₃)₃S]CH₃OSO₃	188.27	mp 92-94°^[8] Crystal structure orthorhombic a=12.6157 b=8.2419 μm c=7.540 cell volume 784.0 2 formulas per unit cell

Preparation[]

Sulfonium compounds can be synthesised by treating a suitable alkyl halide with a thioether. For example, the reaction of dimethyl sulfide with iodomethane yields trimethylsulfonium iodide:

CH₃–S–CH₃ + CH₃–I → (CH₃)₃SI

Related[]

An extra oxygen atom can bond to the sulfur atom to yield the ion.

Use[]

Glyphosate herbicide is often supplied as a trimethylsulfonium salt. When mixed with aluminium bromide, or aluminium chloride or even hydrogen bromide, trimethylsulfonium bromide forms an ionic liquid, which melts at temperatures below standard conditions.^[9]

References[]

^ Knop, Osvald; Cameron, T. Stanley; Bakshi, Pradip K.; Linden, Antony; Roe, Stephen P. (1994). "Crystal chemistry of tetraradial species. Part 5. Interaction Between Cation Lone Pairs and Phenyl Groups in Tetraphenylborates: Crystal Structures of Me₃S⁺,Et3S⁺, Me₃SO⁺, Ph₂I⁺, and 1-Azoniapropellane Tetraphenylborates". Canadian Journal of Chemistry. 72 (8): 1870–1881. doi:10.1139/v94-238.
^ Heilbron's Dictionary of Organic Compounds, volume 4, revised edition published in 1953. Published in Great Britain
^ Blättler, H. (1919). "Über Trimethylsulfoniumverbindungen". Monatshefte für Chemie und verwandte Teile anderer Wissenschaften. 40 (8): 417–429. doi:10.1007/BF01559085. S2CID 197766904.
^ ^a ^b Steinkopf, W.; Müller, S. (1923). "Über die Einwirkung von Jodmethyl auf Disulfide". Chem. Ber. 56 (8): 1926–1930. doi:10.1002/cber.19230560834.
^ Mussgnug, F. (1941). "Trimethylammoniumjodid und Trimethylsulfoniumjodid". Naturwissenschaften. 29 (17): 256. Bibcode:1941NW.....29..256M. doi:10.1007/BF01479158. S2CID 33842580.
^ Zuccaro, D. Ε.; McCullough, J. D. (1 January 1959). "The crystal structure of trimethylsulfonium iodide". Zeitschrift für Kristallographie - Crystalline Materials. 112 (1–6): 401–408. doi:10.1524/zkri.1959.112.jg.401. S2CID 98338161.
^ "Trimethylsulfonium tetrafluoroborate". Sigma-Aldrich. Retrieved 23 September 2016.
^ "Trimethylsulfonium methyl sulfate". Sigma-Aldrich. Retrieved 23 September 2016.
^ Ma, M.; Johnson, K.E. (April 1995). "Some physicochemical characteristics of molten salts derived from trimethylsulfonium bromide". Canadian Journal of Chemistry. 73 (4): 593–598. doi:10.1139/v95-076.