Mg16Al12I crystallizes in the cubic I-43m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to three equivalent Mg(2), six equivalent Al(1), and one I(1) atom. In the second Mg site, Mg(2) is bonded in a 12-coordinate geometry to one Mg(1), six equivalent Mg(2), and five equivalent Al(1) atoms. Al(1) is bonded in a 11-coordinate geometry to two equivalent Mg(1), five equivalent Mg(2), three equivalent Al(1), and one I(1) atom. I(1) is bonded in a distorted tetrahedral geometry to four equivalent Mg(1) and twelve equivalent Al(1) atoms.
Mg16Al12I crystallizes in the cubic I-43m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to three equivalent Mg(2), six equivalent Al(1), and one I(1) atom. All Mg(1)-Mg(2) bond lengths are 3.06 Å. All Mg(1)-Al(1) bond lengths are 3.15 Å. The Mg(1)-I(1) bond length is 3.10 Å. In the second Mg site, Mg(2) is bonded in a 12-coordinate geometry to one Mg(1), six equivalent Mg(2), and five equivalent Al(1) atoms. There are two shorter (3.15 Å) and four longer (3.22 Å) Mg(2)-Mg(2) bond lengths. There are a spread of Mg(2)-Al(1) bond distances ranging from 2.89-3.13 Å. Al(1) is bonded in a 11-coordinate geometry to two equivalent Mg(1), five equivalent Mg(2), three equivalent Al(1), and one I(1) atom. All Al(1)-Al(1) bond lengths are 2.84 Å. The Al(1)-I(1) bond length is 3.33 Å. I(1) is bonded in a distorted tetrahedral geometry to four equivalent Mg(1) and twelve equivalent Al(1) atoms.