Calcium Amidoborane Ammoniate—Synthesis, Structure, and Hydrogen Storage Properties

A new type of hydrogen storage material—namely, calcium amidoborane ammoniate (Ca(NH 2 BH 3 ) 2 ·2NH 3 )—is synthesized by reacting calcium amide and ammonia borane in a molar ratio of 1:2. Structural analyses show that this newly developed complex has a orthorhombic structure (space group Pna 21) with unit-cell parameters of a = 18.673(3) Å, b = 5.2283(8) Å, c = 8.5748(12) Å, and V = 873.16(22) Å 3 . The presence of NH 3 in the crystal lattice facilitates the formation of dihydrogen bonding between BH···HN, which is considerably shorter than that in calcium amidoborane (Ca(NH 2 BH 3 ) 2 ). As a consequence, the bond lengths of B−H and N−H are increased comparatively. Our experimental results show that more than 8 wt % hydrogen can be released from Ca(NH 2 BH 3 ) 2 ·2NH 3 without borazine emission at 150 °C.