Substituted Ammonia Borane (AB) compounds could be an alternative energy resource utilized to store and release molecular hydrogen. Ammonia Borane derivatives substituted with electron donating and electron withdrawing groups alters the mechanism for the storage of hydrogen. The release of hydrogen molecules from Ammonia Borane derivatives were computed using Gaussian 09 at B3LYP/6-311+G(d,p) and CBS-QB3 levels of theory. With its high hydrogen content (19% wt/wt) it is known that AB can thermally release up to 2 equivalents of molecular hydrogen on monosubstituted AB. The effects of monosubstitution at the N or B with varying degrees of electronegativity, was found to have a direct influence on changes in the reaction free energy for the release of hydrogen. Specifically, it was found that donating groups were best located on the nitrogen atom, whereas electron withdrawing groups were best found on the boron atom for monosubstituted AB. In this research study, the substituent group effect on hydrogen release was further investigated, specifically by the introduction of an assortment of electron donating and withdrawing groups on disubstituted AB in different conformations. Locking the rotational freedom of the nitrogen boron via a five or six membered ring is also investigated.

Theoretical investigations of the utility of disubstituted ammonia borane derivatives for hydrogen storage

247th National Meeting (2014)

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