Hydrides of silicon

The hydrides of silicon (silicon plus hydrogen) are extremely volatile and spontaneously burst into flames in air at room temperatures. They must be kept in special vacuum chambers. 

Exposure of silicon to atomic hydrogen increases the surface recombination velocity.111213 The free energy of formation of SiH4, the most stable of the hydrides of silicon, is only — lOKcal/mole. Since four electron pairs are shared in the formation of the molecule, the free energy of formations per Si-H bond is only -2.5 Kcal or about O.leV. Because of the weak chemisorption, heating of the silicon to temperatures above 500 C is adequate to release the hydrogen. Our model explains the increase in surface recombination velocity by the weak chemisorption of hydrogen, which may increase the density of surface states within the band gap (see Fig. 2b). 

EXAMPLE 2 A hydride of silicon that has the empirical formula SiH3 (approximately 31 g/empirical formula) was found to have an approximate gas density at S.T.P. of 2.9 g/L. By comparison with oxygen, whose molecular mass and density are known, the molecular mass of the hydride is... 

Procedures similar to those described for the preparation of diborane can be employed for the preparation of the hydrides of silicon and germanium. For example, Mg2Si results when Mg and Si react. This compound reacts with HC1 to produce silane, SiH4 ... 

Silane and disilane (Si2H6) are the only stable hydrides of silicon because the higher members of the series decompose to produce SiFLt, Si2H6, and H2. Silicon hydrides are spontaneously flammable in air (see Chapter 6) ... 

If the reader has any doubts about this point, let him attempt to predict the behavior of the hydrides of silicon from a consideration of the hydrocarbons. It will soon be seen that the hydrides of boron offer a much closer analogy. 

Monosilane. SiBU, the simplest normal hydride of silicon. 

Silane. The name given to a hydride of silicon of the type SinH2n+2, or a derivative thereof. 

Lanthanide alkyl and aryl complexes react with organoelement hydride compounds, such as hydrides of silicon, germanium, and tin, and so on, resulting in a hydride transfer to the lanthanide metal atom. Among the organoelement hydrides, organosilanes are the most popular source of the hydride. 

The Hydrides of Silicon. The hydrides of silicon, called the silicanes or silanes, have the general formula SinHon -a, analogous to that of the paraffin series in organic chemistry. The silanes are made by reaction of metallic silicides with water or acid for example, mag nesium silicide with acid produces inonosilane, SiH ... 

Volatile compounds of the hydrides of silicon and germanium with elements of groups V and VI... 

J. E. Drake, Ch. Riddle, Volatile Compounds of Hydrides of Silicon and Germanium with Elements of Group V and VI", Quart. Rev. 1970, 24, 263. 

Separations of hydrides of silicon and germanium have been achieved by GC on ester and silicone phases. Separation of alkyltin mono- and dihydrides by GC requires the use of most inert stationary phases to preclude on-column reaction. Among the Group IVA elements, lead alone has hydrides for which GC has not proved possible. 

Silane a hydride of silicon that contains chains of single-bonded silicon atoms. (22.6)... 

The subject dealt with in this volume is concerned with the analysis of all types of organometallic compounds and includes, where relevant, a discussion of metal hydrides, e.g. hydrides of silicon. 

Lukevics, E. and Voronkov, M. G., Addition Products from Organic and Inorganic Hydrides of Silicon, Germanium, Tin and Lead, Izd. Akad. Nauk Latv. SSSR, Riga, 1904.. 

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