“…Recently, the incorporation of ammonia in the clathrate structure, either within the water cavities or as part of the host lattice, has been reported for hydrogen-bonding guests, such as THF. − This incorporation could actually be facilitated by host–guest hydrogen bonds, which disrupt the intrinsic water–water hydrogen bonds in the host lattice and create Bjerrum defects . On the other hand, stable NH 3 incorporation in methane clathrates is still debated ,,, and appears to be strongly dependent upon formation conditions. The incorporation of ammonia in clathrates has been supported in CH 4 clathrates synthesized from cryogenic vapor deposition methods at relatively low NH 3 concentrations (5 wt % or less), while it was not required to explain results obtained on CH 4 clathrates formed from freezing of aqueous solutions. , This emphasizes that the chemical system and formation method must be considered when discussing stable NH 3 incorporation in clathrate hydrates …”