Английская Википедия:Difluorosilane
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.
Production
Difluorosilane can be made by fluorinating dichlorosilane with antimony trifluoride. [1] [2]
- 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.[3]
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.[4]
Reactions
In an electric discharge, hydrogen atoms are preferentially removed from the molecule and SiHF2SiHF2 is formed along with hydrogen.[2]
- 2 SiH2F2 → SiHF2SiHF2 + H2
At elevated temperatures, difluorosilane can disproportionate by swapping hydrogen and fluorine atoms between molecules to form fluorosilane and trifluorosilane.[4]
Use
Difluorosilane is used in dental varnish in order to prevent tooth cavities.[5]
Difluorosilane is also used in chemical vapour deposition to deposit silicon nitride films.
References
- ↑ 郝润蓉 等. 无机化学丛书 第三卷 碳 硅 锗分族. 科学出版社, 1998. pp 178. 2.3 卤代硅烷
- ↑ 2,0 2,1 Шаблон:Cite book
- ↑ Шаблон:Cite journal
- ↑ 4,0 4,1 Шаблон:Cite book
- ↑ Шаблон:Cite journal
