Silicon hydrides boron halides

Boron differs from aluminum in showing almost no metallic properties and its resemblance to silicon is greater. Both boron and silicon form volatile, very reactive hydrides the hydride of aluminum is a polymeric solid. The halides (except BF3) hydrolyze to form boric acid and silicic acid. The oxygen chemistry of the borutes and silicates also has certain resemblances. 

All the hydrides of boron, except B9H15 recently isolated by Schaeffer, were discovered by Stock (1914-20). The starting material was the gaseous product of the reaction between magnesium boride and dilute hydrochloric acid. His remarkable success was due to a vacuum technique which he developed for handling compounds sensitive to oxygen and moisture, such as the hydrides of boron and silicon. Monomeric BH3 was not found because there are insufficient electrons to stabilise the bonding in such a compound, as it is stabilised in the monomeric boron halides. 

The simplest hydrides and halides of boron, silicon, germanium, phosphorus, and arsenic can be decomposed in electric discharges to form... 

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