Silicon difluoride

Silicon difluoride is obtained as a very reactive gas when silicon tetrafluoride and silicon are heated together. It polymerises rapidly to give (SiF2) , a solid. 

Ultraviolet Spectra. The first direct evidence for the existence of gas phase monomeric silicon difluoride resulted from observation of emission spectra of the molecule in an electric discharge through SiF4 9 The emission band system was subsequently extended 60however, both of these investigations are now thought... 

An interesting class of compounds of the formula ArH(SiF2) , where n = 2 to 8, has recently been prepared by the reaction of silicon difluoride with aromatic compounds at low temperatures (186). The compounds... 

Formation of polymeric (SiF2) or (SiF) is possible in the reaction of SiBr2F2 or SiBr3F, respectively, with magnesium360 548). Silicon monofluoride was also obtained on heating silicon difluoride to 200—350 °C. At higher temperature (400 °C) an explosive decomposition into silicon and SiF4 occurs. 

Thompson, J. C., J. L. Margrave, and P. L. Timms Reaction of Silicon Difluoride with Ethylene and with Fluorinated Ethylene Derivatives. Chem. Commun. 1966, 566—567. 

D. D. Stump, R. A. Kent, and J. L. Margrave Silicon-Fluorine Chemistry. IV. The Reaction of Silicon Difluoride with Aromatic Compounds. J. Amer. chem. Soc. 88, 940 (1966). SiF2. Expanding Silicone-Fluorine Chemistry. Chem. Engng. News 43, 40 (1965). 

The divalent dissolution of Si was then described by a two-dimensional reaction scheme at a kink site on a silicon surface (not shown) assuming the surface to be covered by fluorine instead of hydroxyl groups [8]. It was further postulated that the unstable silicon difluoride changes into a stable tetravalent form by a disproportionation reaction [9] ... 

SiOF2[g] SILICON DIFLUORIDE OXIDE (GAS) 1506 Sn2l4[g] DITIN TETRAIODIDE (GAS) 1548... 

Silicon tetrafluoride reacts with pure silicon at low pressure in a flow system at 1200 °C to yield a transient species, SiF2, which can be condensed to yield a fluorosilane polymer, (SiF2) . Silicon difluoride has a half-life of about 150s in glass at low pressure in the gas phase. The chemistry of Sip2 shows many different reactions and has been reviewed. When condensed at —196 °C, a red-yellow deposit is formed,... 

The products obtained from the reactions of 3,3,3-trifluoro-2-trifluoromethyl-propionic acid and 2,3,3,3-tetrafluoropropionyl fluoride with sulphur trioxide depend on the reaction ratio employed (see Schemes 15 and 16). Interestingly, treatment of trifiuoroacetyl chloride with silicon difluoride at low temperature gives a volatile 2 4 adduct postulated, on the basis of spectroscopic studies, to have... 

Polymeric sulfur Silicon difluoride Poly(diphenyl siloxane) Poly(phosphoronitrilochloride) ... 

Silicon difluoride reacts with the fluoro-olefins CH2.CHF, CH2 CFMe, CHj CF2, and CF2 CHF by insertion into the C F bond. Free-radical additions of triethylsilane to 1,2-dichloro-tetrafluorocyclobutene, -hexa-fluorocyclopentene, and -octafluorocyclohexene, and of the silanes HSiCl2Ph. HSiClj, HSiClgMe, HSiClMcj, and HSiEtg to the same cyclo-butene and cyclopentene, and the corresponding monochloro-compounds, have been described (see p. 200). Addition is accompanied by reduction of chlorine. 

The difluoroiodosilanes RpSiFtI (Rf = CFa or CaFs) required in the above work were synthesized via insertion of silicon difluoride into the C—bonds of the corresponding perfluoroiodoalkanes (c/. Vol. 1, p. 89). The alkenes CF.iCH SiFa plus CF CH SiF, SiF, and CHjtCF SiF, plus CHjiCfSiF have been identified as volatile products of attack on trifluoroethylene and vinylidene fluoride, respectively, by silicon difluoride, and the cyclic compounds (16) and (17) from reactions involving 3,3,3-trifluoropropyne. ... 

The fluorination procedure is applicable to methylsiloxane pol3miers only. The presence of ethylsiloxane complicates results since ethylsilicon trifluoride is eluted at the same time as dimethyl silicon difluoride. 

In Figure 84 is shown a chromatogram of a mixture of silicon tetrafluoride, phenylsilicon trifluoride and phenyl methyl silicon difluoride obtained by fluorination of a mixture of phenyl methyl silicon dichloride and phenyl silicon trichloride. 

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