Crystal design by CH...N and N...N interactions: high-pressure structures of high-nitrogen-content azido-triazolopyridazines compounds.

High-nitrogen-content compounds 6-azido-1,2,4-triazolo[4,3-b]pyridazine (C5H3N7) and its 3-methyl derivative (C6H5N7) have been in situ crystallized in a diamond-anvil cell and their structures determined by single-crystal X-ray diffraction. Under ambient and high-pressure conditions the crystallizations yield the same phases: the C5H3N7 anhydrate and C6H5N7 hydrated clathrate. In both the structures there are clearly distinguished regions of short CH...N and N...N intermolecular contacts, the latter involving exclusively the azide groups. High pressure initially increases the contents of water in the channel pores of the clathrate.