The Role of Oxophilicity and Water for Coordination Complexes as Ammonia Stores

Ammonia has become one of the hopeful vectors for a carbon‐free hydrogen storage economy. Given its toxicity, storing ammonia affords some special precautions, which can be met with solid state stores in the form of ammine complexes. We have studied the role of water in the reactions of multiple metal salts (Ni ²⁺ , Cu ²⁺ , Cr ³⁺ , Mn ²⁺ , Co ²⁺ Sn ²⁺ salts) with gaseous ammonia at ambient conditions. We find that the oxophilicity of the cations is of crucial importance to avoid side reactions that lead to the formation of side products, which prevent cyclability of these materials as a crucial factor for their sustainable use.