Base Metal Catalyzed Dehydrogenation of Ammonia−Borane for Chemical Hydrogen Storage

We report here the first example of a homogeneous first row transition-metal-based catalyst which is active for dehydrogenation of ammonia−borane, H3NBH3, a promising chemical hydrogen storage material. Addition of ammonia−borane to an active catalyst formed in situ from the reaction of Ni(cod)2 and 2 equiv of an appropriate N-heterocyclic carbene (NHC) rapidly evolves hydrogen at 60 °C. Using a gas burette to quantify the gas evolved, 29 of a possible 31 mL of H2 for 3 equiv of H2 was produced, equating to >2.5 equiv of H2 from ammonia−borane. Kinetic isotope effects of deuterated derivatives of ammonia−borane suggest that both N−H and B−H bonds are being broken in the rate-determining step(s).