Halohydrides of silicon and germanium

Of compounds of the type SiH X4 (X = halogen, n = 1-3), SiHCls is of particular importance in the purification of Si in the semiconductor industry (equation 13.25). The success of the second step in scheme 13.25 depends on the precursor being volatile. SiHCl3 (mp 145 K, bp 306 K) is ideally suited to the process, as is SiH4 (mp 88 K, bp 161 K). 

Another application of SiHCl3 is hydrosilation (equation 13.26), a method of introducing an SiCl3 group and an entry to organosilicon chemistry. 

The halo-derivatives SiH2X2 and SiH3X (X = Cl, Br, I) can be prepared from SiH4 (eq. 14.31) and some reactions of SiH3Cl (bp 243 K) are shown in Fig. 14.12. The ease with which SiH X4 compounds hydrolyse releasing HX means that they must be handled in moisture-free conditions. The preparation and reactivity of GeH3Cl resemble those of SiH3Cl. 

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