Metal-Free Ammonia-Borane Dehydrogenation Catalyzed by a Bis(borane) Lewis Acid

The storage of energy in a safe and environmentally benign way is one of the main challenges of today's society. Ammonia-borane (AB= NH3BH3) has been proposed as a possible candidate for the chemical storage of hydrogen. However, the efficient release of hydrogen is still an active field of research. Herein, we present a metal-free bis(borane) Lewis acid catalyst that promotes the evolution of up to 2.5 equivalents of H-2 per AB molecule. The catalyst can be reused multiple times without loss of activity. The moderate temperature of 60 degrees C allows for controlling the supply of H-2 on demand simply by heating and cooling. Mechanistic studies give preliminary insights into the kinetics and mechanism of the catalytic reaction.