There are growing demands to reduce the global CO2 footprint and to adopt alternative, sustainable fuels. Ammonia (NH3) is one such alternative, producing only water and nitrogen on combustion. However, the toxicity of NH3 is a major drawback that can make its handling and storage very difficult. Storing NH3 in the solid state as metal ammine complexes is one possible solution offering both high gravimetric and volumetric density. Recently, we have been studying CrCl2 to elucidate the mechanisms of NH3 uptake and release in this interesting system, which can theoretically store large amounts of NH3. We propose here to derive the structures of the Cr ammines for the first time and to understand the mechanisms by which ammonia is released. This should help us design improved ammine materials with superior NH3 storage properties.