The crystal structure of γ-AlD3

γ-AlD3 was synthesized from LiAlD4 and AlCl3 via thermal decomposition of aluminum hydride etherate in presence of excess LiAlD4. γ-AlD3 was determined by powder neutron diffraction and synchrotron X-ray diffraction to crystallize in the space group Pnnm. The orthorhombic structure has unit-cell dimensions a = 7.3360(3) Å, b = 5.3672(2) Å and c = 5.7562(1) Å, and it consists of both corner- and edge-sharing AlD6 octahedra where each hydrogen is shared between two octahedra. The average Al–D distances in octahedra with edge-sharing is 1.706 Å and in the octahedra with only corner-sharing 1.719 Å.