AlH3 crystallizes in the orthorhombic Pnnm space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one H(3), one H(4), two equivalent H(1), and two equivalent H(2) atoms to form a mixture of corner and edge-sharing AlH6 octahedra. The corner-sharing octahedral tilt angles range from 0-46°. In the second Al site, Al(2) is bonded to two equivalent H(3) and four equivalent H(1) atoms to form corner-sharing AlH6 octahedra. The corner-sharing octahedral tilt angles range from 12-46°. There are four inequivalent H sites. In the first H site, H(1) is bonded in a distorted bent 120 degrees geometry to one Al(1) and one Al(2) atom. In the second H site, H(2) is bonded in a water-like geometry to two equivalent Al(1) atoms. In the third H site, H(3) is bonded in a linear geometry to one Al(1) and one Al(2) atom. In the fourth H site, H(4) is bonded in a linear geometry to two equivalent Al(1) atoms.
AlH3 crystallizes in the orthorhombic Pnnm space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one H(3), one H(4), two equivalent H(1), and two equivalent H(2) atoms to form a mixture of corner and edge-sharing AlH6 octahedra. The corner-sharing octahedral tilt angles range from 0-46°. The Al(1)-H(3) bond length is 1.69 Å. The Al(1)-H(4) bond length is 1.67 Å. Both Al(1)-H(1) bond lengths are 1.72 Å. There is one shorter (1.71 Å) and one longer (1.75 Å) Al(1)-H(2) bond length. In the second Al site, Al(2) is bonded to two equivalent H(3) and four equivalent H(1) atoms to form corner-sharing AlH6 octahedra. The corner-sharing octahedral tilt angles range from 12-46°. Both Al(2)-H(3) bond lengths are 1.74 Å. All Al(2)-H(1) bond lengths are 1.71 Å. There are four inequivalent H sites. In the first H site, H(1) is bonded in a distorted bent 120 degrees geometry to one Al(1) and one Al(2) atom. In the second H site, H(2) is bonded in a water-like geometry to two equivalent Al(1) atoms. In the third H site, H(3) is bonded in a linear geometry to one Al(1) and one Al(2) atom. In the fourth H site, H(4) is bonded in a linear geometry to two equivalent Al(1) atoms.