M(BH3NH2BH2NH2BH3) – the missing link in the mechanism of the thermal decomposition of light alkali metal amidoboranes

Abstract

We report a novel family of hydrogen-rich materials – alkali metal di(amidoborane)borohydrides, M(BH₃NH₂BH₂NH₂BH₃). The title compounds are related to metal amidoboranes (amidotrihydroborates) but have higher gravimetric H content. Li salt contains 15.1 wt% H and discharges very pure H₂ gas. Differences in thermal stability between amidoboranes and respective oligoamidoboranes explain the release of the ammonia impurity (along with H₂) during the thermal decomposition of light alkali amidoboranes, LiNH₂BH₃, NaNH₂BH₃ and NaLi(NH₂BH₃)₂, and confirm the mechanism of the side decomposition reaction.