Question

The major product formed from the reaction between B$_2$H$_6$ and two equivalents of NH$_3$ at 300 $^\circ$C is _ _ _.

• A. BH$_3\cdot$NH$_3$
• B. [NH$_4$]$^+$ [BH$_4$]$^-$
• C. [(H$_3$N)$_2$BH]$^{2+}$ 2[BH$_4$]$^-$
• D. (HBNH)$_3$

Hint:

At high temperature, ammonia borane loses hydrogen and forms borazine (HBNH)$_3$, an aromatic inorganic compound

Answer 1

The Correct Option is D

Step 1: Initial reaction.
Diborane reacts with ammonia to initially form an adduct BH$_3\cdot$NH$_3$ (ammonia borane)

Step 2: Effect of high temperature.
At elevated temperature (300 $^\circ$C), ammonia borane undergoes dehydrogenation (loss of H$_2$ gas)

Step 3: Polymerization.
The dehydrogenation leads to formation of borazine-type cyclic compound (HBNH)$_3$, which is often called inorganic benzene

Step 4: Conclusion.
\[ \boxed{(HBNH)_3} \]