tetramethylsilaan

Tetramethylsilane, also known as tetramethylsilane or TMS, is an organosilicon compound with the formula Si(CH3)4. It is a colorless, volatile compound that is commonly used in spectroscopy as a reference standard. The molecule features a silicon atom bound to four methyl groups in a tetrahedral geometry and contains no Si–H bonds.

In NMR spectroscopy, tetramethylsilane provides a single, highly shielded signal corresponding to the four equivalent methyl groups. Because its signal is well separated from typical analyte signals and it is chemically inert under many conditions, TMS has long been adopted as the universal internal standard for both 1H and 13C NMR chemical shifts.

Preparation of tetramethylsilane is typically achieved by reacting silicon tetrachloride with methylating reagents. A representative route is SiCl4 reacting with methylmagnesium halide reagents (for example, MeMgBr) to form SiMe4 and magnesium salts, followed by purification and distillation to isolate the product. The reaction requires dry conditions and careful handling due to the reactivity of the intermediates.

Aside from its use as an NMR reference, tetramethylsilane is sometimes employed as a nonpolar, relatively inert medium in certain analytical or preparative contexts, although its primary role remains as a chemical shift standard. The compound is volatile and flammable, and should be stored away from heat and open flames, under appropriate laboratory conditions.

Safety and handling notes emphasize the flammability and the need to minimize inhalation exposure. As with many organosilicon compounds, it should be used with proper ventilation and stored in a labeled container away from incompatible materials.