Computational analysis of amine-borane adducts as potential hydrogen storage materials with reversible hydrogen uptake.

Amine-borane adducts are promising compounds for use in hydrogen storage applications, and the efficient catalytic release of hydrogen from these systems has been recently demonstrated. However, if hydrogen storage is to be of practical use, it is necessary that, once hydrogen has been removed from the material, it can be put back into the system to recharge the appliance. In order to develop such systems, we computationally screened a range of amine-borane adducts for their thermodynamic dehydrogenation properties. Structural trends, which lay the foundation for the possible design of amine-borane systems that exhibit reversible dihydrogen uptake, are established. We found that it is mainly the strengths of the dative bonds in both starting materials and products that govern the thermodynamic parameters of the dehydrogenation reactions. Thus, in general, electron-donating groups on nitrogen and electron-withdrawing groups on boron lead to more favorable systems. It is also possible to design promising systems whose thermodynamic parameters are a consequence of different steric strain in starting materials and products.