Lithium Hydrazinidoborane Ammoniate LiN(2)H(3)BH(3)·0.25NH(3), a Derivative of Hydrazine Borane

Boron- and nitrogen-based materials have shown to be attractive for solid-state chemical hydrogen storage owing to gravimetric hydrogen densities higher than 10 wt% H. Herein, we report a new derivative of hydrazine borane N(2)H(4)BH(3), namely lithium hydrazinidoborane ammoniate LiN(2)H(3)BH(3)·0.25NH(3). It is easily obtained in ambient conditions by ball-milling N(2)H(4)BH(3) and lithium amide LiNH(2) taken in equimolar amounts. Both compounds react without loss of any H atoms. The molecular and crystallographic structures of our new compound have been confirmed by NMR/FTIR spectroscopy and powder X-ray diffraction. The complexation of the entity LiN(2)H(3)BH(3) by some NH(3) has been also established by thermogravimetric and calorimetric analyses. In our conditions, LiN(2)H(3)BH(3)·0.25NH(3) has been shown to be able to release H(2) at temperatures lower than the parent N(2)H(4)BH(3) or the counterpart LiN(2)H(3)BH(3). It also liberates non-negligible amounts of NH(3) at temperatures lower than 100 °C. This is actually quite detrimental for chemical H storage, but alternatively LiN(2)H(3)BH(3)·0.25NH(3) might be seen as a potential NH(3) carrier.