Hexachlorodisilane

Hexachlorodisilane is the inorganic compound with the chemical formula Si₂Cl₆.^[1] It is a colourless liquid that fumes in moist air. It has specialty applications in as a reagent and as a volatile precursor to silicon metal.

Hexachlorodisilane

Names
IUPAC name Hexachlorodisilane
Other names Perchlorodisilane
Identifiers
CAS Number	13465-77-5 Y
3D model (JSmol)	Interactive image
ChemSpider	75334
ECHA InfoCard	100.033.353
EC Number	236-704-1
PubChem CID	83497
UNII	9Z754456JM Y
CompTox Dashboard (EPA)	DTXSID0065488
InChI InChI=1S/Cl6Si2/c1-7(2,3)8(4,5)6 Key: LXEXBJXDGVGRAR-UHFFFAOYSA-N
SMILES [Si]([Si](Cl)(Cl)Cl)(Cl)(Cl)Cl
Properties
Chemical formula	Si2Cl6
Molar mass	268.88 g/mol
Appearance	Colorless liquid
Melting point	−1 °C (30 °F; 272 K)
Boiling point	144 °C (291 °F; 417 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Structure and synthesis

The molecule adopts a structure like ethane, with a single Si-Si bond length of 233 pm.^[2]

Hexachlorodisilane is produced in the chlorination of silicides such as e.g. calcium silicide. Idealized syntheses are as follows:^[3]

CaSi₂ + 4 Cl₂ → Si₂Cl₆ + CaCl₂

Reactions and uses

Hexachlorodisilane is stable under air or nitrogen at temperatures of at least up to 400°C for several hours, but decomposes to dodecachloroneopentasilane and silicon tetrachloride in presence of Lewis bases even at room temperature.^[4]

4 Si₂Cl₆ → 3 SiCl₄ + Si₅Cl₁₂

This conversion is useful in making silicon-based components of use in semiconducting devices including photovoltaic cells.^[1]

The compound is also useful reagent for the deoxygenation reactions, such as this general process involving a phosphine oxide:

2 Si₂Cl₆ + OPR₃ → OSi₂Cl₆ + PR₃