Mg2Cd crystallizes in the hexagonal P-62m space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2); six Mg(1,1); and four equivalent Cd(1) atoms to form distorted MgMg8Cd4 cuboctahedra that share corners with eighteen Mg(1,1)Mg8Cd4 cuboctahedra; edges with four equivalent Mg(2)Mg6Cd6 cuboctahedra; edges with six equivalent Mg(1)Mg8Cd4 cuboctahedra; edges with eight equivalent Cd(1)Mg9Cd3 cuboctahedra; faces with four equivalent Mg(2)Mg6Cd6 cuboctahedra; faces with eight Mg(1,1)Mg8Cd4 cuboctahedra; and faces with eight equivalent Cd(1)Mg9Cd3 cuboctahedra. In the second Mg site, Mg(1) is bonded to two equivalent Mg(2), six equivalent Mg(1), and four equivalent Cd(1) atoms to form distorted MgMg8Cd4 cuboctahedra that share corners with eighteen equivalent Mg(1)Mg8Cd4 cuboctahedra; edges with four equivalent Mg(2)Mg6Cd6 cuboctahedra; edges with six equivalent Mg(1)Mg8Cd4 cuboctahedra; edges with eight equivalent Cd(1)Mg9Cd3 cuboctahedra; faces with four equivalent Mg(2)Mg6Cd6 cuboctahedra; faces with eight Mg(1,1)Mg8Cd4 cuboctahedra; and faces with eight equivalent Cd(1)Mg9Cd3 cuboctahedra. In the third Mg site, Mg(2) is bonded to six Mg(1,1) and six equivalent Cd(1) atoms to form MgMg6Cd6 cuboctahedra that share corners with eighteen equivalent Cd(1)Mg9Cd3 cuboctahedra; edges with six equivalent Mg(2)Mg6Cd6 cuboctahedra; edges with twelve Mg(1,1)Mg8Cd4 cuboctahedra; faces with two equivalent Mg(2)Mg6Cd6 cuboctahedra; faces with six equivalent Cd(1)Mg9Cd3 cuboctahedra; and faces with twelve Mg(1,1)Mg8Cd4 cuboctahedra. Cd(1) is bonded to three equivalent Mg(2); six Mg(1,1); and three equivalent Cd(1) atoms to form distorted CdMg9Cd3 cuboctahedra that share corners with nine equivalent Mg(2)Mg6Cd6 cuboctahedra; corners with nine equivalent Cd(1)Mg9Cd3 cuboctahedra; edges with six equivalent Cd(1)Mg9Cd3 cuboctahedra; edges with twelve Mg(1,1)Mg8Cd4 cuboctahedra; faces with three equivalent Mg(2)Mg6Cd6 cuboctahedra; faces with five equivalent Cd(1)Mg9Cd3 cuboctahedra; and faces with twelve Mg(1,1)Mg8Cd4 cuboctahedra.
Mg2Cd crystallizes in the hexagonal P-62m space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2); six Mg(1,1); and four equivalent Cd(1) atoms to form distorted MgMg8Cd4 cuboctahedra that share corners with eighteen Mg(1,1)Mg8Cd4 cuboctahedra; edges with four equivalent Mg(2)Mg6Cd6 cuboctahedra; edges with six equivalent Mg(1)Mg8Cd4 cuboctahedra; edges with eight equivalent Cd(1)Mg9Cd3 cuboctahedra; faces with four equivalent Mg(2)Mg6Cd6 cuboctahedra; faces with eight Mg(1,1)Mg8Cd4 cuboctahedra; and faces with eight equivalent Cd(1)Mg9Cd3 cuboctahedra. Both Mg(1)-Mg(2) bond lengths are 3.12 Å. There are four shorter (3.10 Å) and two longer (3.19 Å) Mg(1)-Mg(1,1) bond lengths. All Mg(1)-Cd(1) bond lengths are 3.09 Å. In the second Mg site, Mg(1) is bonded to two equivalent Mg(2), six equivalent Mg(1), and four equivalent Cd(1) atoms to form distorted MgMg8Cd4 cuboctahedra that share corners with eighteen equivalent Mg(1)Mg8Cd4 cuboctahedra; edges with four equivalent Mg(2)Mg6Cd6 cuboctahedra; edges with six equivalent Mg(1)Mg8Cd4 cuboctahedra; edges with eight equivalent Cd(1)Mg9Cd3 cuboctahedra; faces with four equivalent Mg(2)Mg6Cd6 cuboctahedra; faces with eight Mg(1,1)Mg8Cd4 cuboctahedra; and faces with eight equivalent Cd(1)Mg9Cd3 cuboctahedra. Both Mg(1)-Mg(2) bond lengths are 3.12 Å. All Mg(1)-Cd(1) bond lengths are 3.09 Å. In the third Mg site, Mg(2) is bonded to six Mg(1,1) and six equivalent Cd(1) atoms to form MgMg6Cd6 cuboctahedra that share corners with eighteen equivalent Cd(1)Mg9Cd3 cuboctahedra; edges with six equivalent Mg(2)Mg6Cd6 cuboctahedra; edges with twelve Mg(1,1)Mg8Cd4 cuboctahedra; faces with two equivalent Mg(2)Mg6Cd6 cuboctahedra; faces with six equivalent Cd(1)Mg9Cd3 cuboctahedra; and faces with twelve Mg(1,1)Mg8Cd4 cuboctahedra. All Mg(2)-Cd(1) bond lengths are 3.13 Å. Cd(1) is bonded to three equivalent Mg(2); six Mg(1,1); and three equivalent Cd(1) atoms to form distorted CdMg9Cd3 cuboctahedra that share corners with nine equivalent Mg(2)Mg6Cd6 cuboctahedra; corners with nine equivalent Cd(1)Mg9Cd3 cuboctahedra; edges with six equivalent Cd(1)Mg9Cd3 cuboctahedra; edges with twelve Mg(1,1)Mg8Cd4 cuboctahedra; faces with three equivalent Mg(2)Mg6Cd6 cuboctahedra; faces with five equivalent Cd(1)Mg9Cd3 cuboctahedra; and faces with twelve Mg(1,1)Mg8Cd4 cuboctahedra. All Cd(1)-Cd(1) bond lengths are 3.13 Å.