Q. Illustrate about Borohydrides?

Borohydrides like NaBH₄,, Be(BH₄,) ₂ and Al(BH₄)are the salts of complex  tetrahydridoborate anion, BH^-₄,. Since in BH^-₄,. boron has a complete octet, the  borohydrides are more stable than the boranes. Sodium borohydride is obtained by the reaction of NaH and methyl borate:

4NaH + B(OMe)₃ ------------------------------------->NaBH₄, + 3CH₃0Na

Other borohydrides are prepared from sodium borohydride. The alkali metal borohydrides are white, non-volatile, ionic solids which are stable in dry air. In contrast to the alkali metal borohydrides Be(BH₄,)₂, and Al(BH₄,)₃, are covalent and  volatile in nature. The alkali metal borohydrides react with water with varying ease.  Thus, LiBH₄, reacts violently with water, KBH₄, can be recrystallised from cold water while KBY, is even more stable.

LiBH₄+ H₂O --------------------------LiBO₂ + 4H₂