Silicon—antimony bonds

This point is illustrated by the silyl halides, whose properties are greatly affected by the presence of a silicon-silicon bond. The preparation of the chloride, bromide and iodide of monosilane is described above the fluoride is made by the action of the chloride on antimony fluoride ... 

It has recently been reported that doping of the polysilanes with antimony pentafluoride results in decomposition of the polymers [12]. In fact, mass spectrometric analysis of gaseous products obtained Irom the doping of poly(methylphenylsilane) with antimony pentafluoride vapor shows the presence of tetrafluorosilane and trifluoromethylsilane. Similar experiments using poly(dimethylsilane) indicate the formation of tetrafluorosilane, trifluoromethylsilane and difluorodimethylsilane. These results clearly show that scission of a silicon-silicon bond occurs during doping, as well as a silicon-phenyl and silicon-methyl bond. 

Alkyl silyl ethers are cleaved by a variety of reagents Whether the silicon-oxygen or the carbon-oxygen bond is cleaved depends on the nature of the reagent used Treatment of alkoxysilanes with electrophilic reagents like antimony tri-fluonde, 40% hydrofluonc acid, or a boron tnfluonde-ether complex results in the cleavage of the silicon-oxygen bond to form mono-, di-, and tnfluorosiloxanes or silanes [19, 20, 21) (equations 18-20)... 

Six elements are metalloids B, Si, Ge, As, Sb, and Te. Of these, silicon is by far the most abundant, making up over 27% of the Earth s crust, more than any other element except oxygen, hi fact, S1O2 and silicate minerals account for 80% of the atoms near the Earth s surface. Despite its great abundance, silicon was not discovered until 1824, probably because the strong bonds it forms with oxygen makes silicon difficult to isolate. Two much rarer metalloids, antimony (known to the ancients) and arsenic (discovered ca. 1250 ad) were isolated and identified long before silicon. 

Silicon forms a series of compounds with antimony analogous to silane. Trisilylstibine, Sb(SiH3)3, has been shown to be pyramidal by electron diffraction.95 There was no evidence of bond angle widening, nor bond shortening, thus suggesting the absence of (p — d)n bonding. The silylstibines are prepared by conventional methods (equation 25). 

In contrast, use of metalloid elements, such as silicon, tin antimony or boron, which can form weak covalent bonds with oxygen, nitrogen or sulfur substituents during the course of the reaction, results in templated products that may be obtained metal-free by simple hydrolysis. These covalent template reactions (the M—X bond is essentially covalent in these cases) also have the advantage that the... 

---