Trimethylsulfoxonium

Trimethylsulfoxonium (abbreviated TMSO) is a cation with a formula (CH3)3SO+ consisting of a sulfur atom attached to three methyl groups and one oxygen atom. It has a net charge of +1.

Production
Refluxing dimethyl sulfoxide with methyl iodide can yield trimethylsulfoxonium iodide.

Reactions
Treated with sodium hydride, trimethylsulfoxonium forms dimethylsulfoxonium methylide.

Trimethylsulfoxonium can polymerise to yield polyethylene.

Copper, zinc and palladium ions in water react with trimethylsulfoxonium and sodium hydroxide to form sulfur ylide complexes.

Properties
In the chloride, the sulfur-oxygen bond length is 1.436 Å, sulfur-carbon bond is 1.742. OSC angles are 112.6°, and CSC angles are 106.2°.