Of the alkaline-earth-metal tetrahydroaluminates, the lighter Mg(AlH4)2 exhibits a sheet structure consisting of octahedrally coordinated Mg atoms interconnected by tetrahedral [AlH4] groups. BaAlH5 as the next heavier compound after calcium tetrahydroaluminate contains onedimensional
zigzag chains of distorted [AlH6] octahedra. Sr2AlD7 structurally contains edge-sharing [DSr4] tetrahedra as well as isolated [AlD6] octahedra.
In the case of calcium tetrahydroaluminate, IR data and the mass balance, including the impurities, such as NaCl and residual organic solvent, suggest a compound with the composition of Ca(AlH4)2 similar to Mg(AlH4)2.