| Transition metal-catalyzed dehydrogenation of amine boranes was studied to explore the potential of such substrates for on-board hydrogen storage applications. The iridium pincer complex (kappa3-1,3-[OP tBu2]2C6H3)Ir(H) 2 previously reported by our group for the catalytic dehydrogenation of ammonia borane (AB) was evaluated for the dehydrogenation of the substituted amine boranes methylamine borane (MeAB) and tert-butyl amine borane (tBuAB) as well as AB/MeAB mixtures. Kinetics, thermodynamics, and product characterizations are reported for these reactions and compared to other amine borane dehydrogenation catalysts. Studies involving other iridium pincer complexes with varying steric and electronic attributes for the dehydrogenation of amine boranes are also discussed. A ruthenium Shvo complex, cobalt and iron salen complexes, as well as (1,2-bis(2'-aminoethoxy)ethane)CoCl 2 were also explored as potential catalysts for the dehydrogenation of AB which could operate by an ionic mechanism. The dehydrogenation of AB with a cobalt alkoxide dimer, K2Co2(mu 3-OtBu)2(mu2OtBu) 4, and CoCl2/NaOtBu mixtures are also reported. Evaluation of these systems with regards to the Department of Energy (DOE) targets, as well as the implications of our results for hydrogen storage in general is discussed. |
