Towards Y(NH2BH3)3: Probing hydrogen storage properties of YX3/MNH2BH3 (X = F, Cl; M = Li, Na) and YHx∼3/NH3BH3 composites

Alkali and alkaline-earth metal amidoboranes constitute a new class of inorganic hydrogen storage materials containing distinct [NH2BH3]− units. Here we have attempted synthesis of one of the lightest among M(III) amidoboranes, Y(NH2BH3)3, with its high nominal hydrogen content of 8.4 wt.%, using few different routes. Polycrystalline Y(NH2BH3)3, successfully obtained via mechanochemical synthesis utilizing LiNH2BH3 and YCl3, has been subject to structural and spectroscopic investigations as well as studies of thermal decomposition. Y(NH2BH3)3 crystallizes monoclinic (C2/c) with a = 13.18902(63) Å, b = 7.82233(38) Å, c = 14.874274(68) Å, β = 92.42620(40)° (Z = 8, V = 1533.19(13) Å3). The title compound is quite unstable at ambient conditions and it spontaneously decomposes within several days. When heated up in argon, it exothermally emits hydrogen contaminated with significant amount of ammonia, in the 50–250 °C temperature range.