N-substituted amine-borane ionic liquids as fluid phase, hydrogen storage materials

A selection of task specific N-substituted amine-borane ionic liquids (N-ABILs) were synthesized in good yield using sityt protecting groups with the aim of developing hydrogen (H-2) storing fuels for automotive applications. A new anhydrous anion exchange method, based on trimethylsityl reagents, was employed so sensitive pendant functionalities like borane could be incorporated. Controlled thermoylsis of N-ABILs indicate members of this class may be liquids pre- and post-dehydrogenation, joining a relatively small population of putative H-2 storing fuels that can be readily loaded/unloaded from a vehicle. N-ABILs were also blended with ammonia-borane to improve overall H-2 capacity, in one case by similar to 2.5x. The products of thermolysis consist of co-oligomerized BN species and highly pure (<1% impurity) H-2 gas.