Tetramethylsilane

Tetramethylsilane (TMS) is a chemical compound with the formula Si(CH3)4. It is the simplest tetraorganosilane and an archetype for the organosilanes, compounds containing carbon-silicon bonds. TMS is a building block in organometallic chemistry but also finds use in diverse niche applications.

Structure and bonding

Tetramethylsilane is tetrahedral in its molecular geometry, reflecting the tetrahedral coordination geometry about silicon that is common in organosilicon chemistry. The Si-C bond length is 186 pm, and the C-Si-C bond angle is 111°. The Si-C bond strength is 318 kJ/mol, which is stronger than the Si-O bond in the silicon mineral quartz (SiO2), reflecting the greater stability of the Si-C bond.

Synthesis and reactions

Tetramethylsilane is prepared by the reaction of methyl chloride with silicon in the presence of a catalyst, such as copper: Si + 4 CH3Cl → Si(CH3)4 + 4 Cl−

Tetramethylsilane undergoes reactions typical of other tetraorganosilanes. It can be converted to silicon tetrachloride by reaction with chlorine: Si(CH3)4 + 4 Cl2 → SiCl4 + 4 CH3Cl

Applications

Tetramethylsilane is commonly used as a standard in 1H NMR spectroscopy. It is also used as a precursor to various silicon-containing polymers and ceramics.

Safety

Tetramethylsilane is a highly flammable liquid. It can form explosive mixtures with air and should be handled with appropriate safety precautions.

See also

• Silane
• Organosilicon
• Silicon tetrachloride

References

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