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 center dot center dot center dot N and N center dot center dot center dot 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.