Difluorosilane
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3D model (JSmol) |
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PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |||
| F2H2Si | |||
| Molar mass | 68.098 g·mol−1 | ||
| Appearance | colourless gas | ||
| Melting point | −122 °C (−188 °F; 151 K) | ||
| Boiling point | −77.8 °C (−108.0 °F; 195.3 K) | ||
| Thermochemistry[1] | |||
Std molar entropy (S⦵298) |
262.12 J/mol•K | ||
Std enthalpy of formation (ΔfH⦵298) |
−790.78 kJ/mol | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Difluorosilane is a gaseous chemical compound with formula SiH2F2. It can be considered as a derivative of silane with two hydrogen atoms replaced with fluorine.
Difluorosilane can be made by fluorinating dichlorosilane with antimony trifluoride.[2][3]
- 3 SiH2Cl2 + 2 SbF3 → 3 SiH2F2 + 2 SbCl3
Some is also made in a reaction of silicon tetrafluoride with hydrogen
- SiF4 + 2 H2 → SiH2F2 + 2 HF
Traces of difluorosilane are made when coal is burnt.[4]
Properties
Difluorosilane is a gas with boiling point −77.8 °C, and a freezing point of −122 °C. It has no colour. The silicon–fluorine bond length in difluorosilane is 1.358 Å which is greater than that in fluorosilane but less than the length in trifluorosilane.[5]