Boron forms hydrides of the types B_nH_n+14 and B_nH_n+6 called boranes. Diborane is the simplest boron hydride which is a dimer of BH₃ .

(b) 4BCI₃ + LiAIH₄ ——→2B₂H₆ + 3ACI₃ + 3LiCI

(c) In the laboratory, it is prepared by the oxidation of sod. Borohydride with I₂ .

Properties : (a) Since Boron in boranes never complete its octet of electrons hence all boranes are called as electron-deficient compounds or Lewis acids.

(b) All boranes catch fire in the presence of oxygen to liberated a lot of heat energy. Thus, they can also be used as high energy fuels.

B₂H₆ + 3O₂ ——→ 2B₂O₃ + 3H₂O; H = - 1976 KJ / mole

(c) Boranes are readily hydrolysed by water.

B₂H₆ + 6H₂O ——→ 2H₃BO₃ + 6H₂

(d) With carbon monoxide

B₂H₆ + 2CO ———→ ( BH₃ ← CO)₂

(e) Boranes are used for formation of hydroborates or borohydrides such as LiBH₄ or NaBH₄ , which are extensively used as reducing agents in organic synthesis.

Structure of diborane : B₂H₆ has a three centre electron pair bond also called a banana shape bond.

(b) B - H_b : This is a bond between three atoms, (three centre electron pair bond i.e., 3c - 2e )

or

Structure of diborane ( B₂H₆ )