Hydrides of the Group IVA Elements

The elements Si, Ge, Sn, and Pb all exhibit the oxidation states of +2 and +4. However, the +2 state for Si is rare. One reason is that SiO is not stable and the halides SiF2 and SiCl2 are polymeric solids. A few Ge(II) compounds are known (e.g., GeO, GeS, and Gel2). The +2 and +4 oxidation states are about equally common for Sn and Pb. For example, Sn02 is the most common ore of Sn, and numerous compounds contain Sn(II) (stannous compounds). As we will see later, there are also numerous common compounds of both Pb(II) and Pb(IV). 

Alfred Stock prepared silicon hydrides by the means of the following reactions  

Silane can also be prepared by the reaction of Si02 or SiCl4 with LiAlH4 as represented by the equations 

SiCl4 + LiAIH4 SiH4 + LiCl + A1C13 (LiAlCl4) (11.10) 

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)  

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