Ca(AlH4)2 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a 10-coordinate geometry to two equivalent H(1), four equivalent H(2), and four equivalent H(3) atoms. Al(1) is bonded to one H(2), one H(3), two equivalent H(1), and two equivalent H(4) atoms to form edge-sharing AlH6 octahedra. There are four inequivalent H sites. In the first H site, H(1) is bonded in a distorted T-shaped geometry to one Ca(1) and two equivalent Al(1) atoms. In the second H site, H(2) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one Al(1) atom. In the third H site, H(3) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one Al(1) atom. In the fourth H site, H(4) is bonded in a water-like geometry to two equivalent Al(1) atoms.
Ca(AlH4)2 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a 10-coordinate geometry to two equivalent H(1), four equivalent H(2), and four equivalent H(3) atoms. Both Ca(1)-H(1) bond lengths are 2.39 Å. There are two shorter (2.33 Å) and two longer (2.58 Å) Ca(1)-H(2) bond lengths. There are two shorter (2.33 Å) and two longer (2.55 Å) Ca(1)-H(3) bond lengths. Al(1) is bonded to one H(2), one H(3), two equivalent H(1), and two equivalent H(4) atoms to form edge-sharing AlH6 octahedra. The Al(1)-H(2) bond length is 1.68 Å. The Al(1)-H(3) bond length is 1.70 Å. There is one shorter (1.78 Å) and one longer (1.83 Å) Al(1)-H(1) bond length. There is one shorter (1.72 Å) and one longer (1.77 Å) Al(1)-H(4) bond length. There are four inequivalent H sites. In the first H site, H(1) is bonded in a distorted T-shaped geometry to one Ca(1) and two equivalent Al(1) atoms. In the second H site, H(2) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one Al(1) atom. In the third H site, H(3) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one Al(1) atom. In the fourth H site, H(4) is bonded in a water-like geometry to two equivalent Al(1) atoms.