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

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.