Because Boron is directly to the left of Carbon and Nitrogen is directly to the right of Carbon on the Periodic Table Boron-Nitride has the same types of bonds and so as carbon and so in combination with other elements it can form Molecules with the same shape as carbon atoms. Because Boron-Nitride forms molecules with the same shape as carbon molecules Boron-Nitride has been suggested as a possible alternative to carbon as a building block for Extra-Terrestrial life.
Ammonia could also be an alternative to water as a solvent for Extra-Terrestrial life as it is also a polar molecule that in liquid form is capable of dissolving a variety of substances including organic substances.
Even at the temperature of Liquid Ammonia Diborane is a gas meaning that it could get into the atmosphere of a planet that has high concentrations of it.
The only problem for Boron-Nitride being a building block for Extra-Terrestrial life is that Boron is very rare.
Is there any way a planet could have high concentrations of Boron in its atmosphere and on its surface? Would Diborane have any effect on the temperature of a planet? What color would the sky of a planet with Diborane, Nitrogen, and Ammonia in its atmosphere be?