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?

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    $\begingroup$ "Could such a planet exist?" Probably. "Would it have life?" We don't know, so far we've only found 1 planet with life on it, and we don't have a good definition of "life." "Color of the sky?" Now that is a good question. $\endgroup$ Feb 5, 2016 at 21:12

1 Answer 1


Nitrogen and ammonia? No problem.

Diborane? Not so easy. The problem is, diborane has a positive enthalpy of formation. That means that it prefer to remain as boron and hydrogen separately. Despite that, it is less reactive than you would expect. Furthermore your atmosphere has a compatibility issue, diborane reacts with ammonia to form the diammoniate salt.

On the other hand, the planet in question has life, and that is important, as such places tend to not be in thermodynamic equilibrium. We do for instance have large amounts of flammable material combined with an atmosphere containing oxygen. If some process on the surface constantly release new diborane to the atmosphere it is not going to be a problem.

As for the colour of the sky, things start off normal with ammonia and nitrogen: Transparent with white clouds. I had a hard time trying to find spectral data for diborane, but I found a lot of images showing nice, green flames:

diborane fire

Probably not hundred percent accurate, but I like to imagine an atmosphere with a weak green glow.

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    $\begingroup$ I don't think flame color is a good indicator of a gas's color in an atmosphere. $\endgroup$ Jun 20, 2016 at 22:23
  • $\begingroup$ @MackTuesday Me neither :) $\endgroup$ Jun 20, 2016 at 22:25
  • $\begingroup$ Flame color is the direct opposite of a gas's color in an atmosphere, in fact; the colors that it emits when excited are precisely the colors that it would absorb from the atmosphere. So, take the green out of white and you're left with a purple tint. $\endgroup$ Aug 20, 2019 at 18:07
  • $\begingroup$ Oxygen is thermodynamically stable, in that if there is nothing for it to react with it will just sit there. But diborane isn't, so it will decompose over time. On Earth, most of the material that can react with oxygen is deep underground (fossil fuels), so oxygen is stable until geological processes dredge enough of these reducing agents up. $\endgroup$ Feb 5, 2021 at 8:05

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