Reaction of diborane with ammonia gives initially

Diborane with ammonia gives an addition product, B₂H₆.2NH₃ which is formulated as ${\left[{\mathrm{BH}}_2\left({\mathrm{NH}}_3\right)\right]}^{+}{\left[{\mathrm{BH}}_4\right]}^{-}$. 

${\mathrm{B}}_2{\mathrm{H}}_6+{\mathrm{NH}}_3\underset{\mathrm{low} \mathrm{temperature}}{\overset{\mathrm{excess} {\mathrm{NH}}_3}{\to }}3{\left[{\mathrm{BH}}_2{\left({\mathrm{NH}}_3\right)}_2\right]}^{+}{\left[{\mathrm{BH}}_4\right]}^{-}$
This addition product forms a volatile compound named as borazine or borazole when heated to 473 K.

$3[{\mathrm{BH}}_2{\left({\mathrm{NH}}_3\right)}_2{]}^{+}{\left[{\mathrm{BH}}_4\right]}^{-}\stackrel{473 \mathrm{K}}{\to }2{\mathrm{B}}_3{\mathrm{N}}_3{\mathrm{H}}_6+12{\mathrm{H}}_2$