MgCd2 crystallizes in the orthorhombic Cmcm space group. Mg(1) is bonded to two equivalent Cd(2) and four equivalent Cd(1) atoms to form distorted MgCd6 cuboctahedra that share corners with two equivalent Mg(1)Cd6 cuboctahedra, corners with six equivalent Cd(1)Mg4Cd8 cuboctahedra, corners with twelve equivalent Cd(2)Mg2Cd10 cuboctahedra, edges with six equivalent Mg(1)Cd6 cuboctahedra, edges with seven equivalent Cd(2)Mg2Cd10 cuboctahedra, edges with seven equivalent Cd(1)Mg4Cd8 cuboctahedra, and faces with two equivalent Cd(2)Mg2Cd10 cuboctahedra. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to four equivalent Mg(1), two equivalent Cd(1), and six equivalent Cd(2) atoms to form distorted CdMg4Cd8 cuboctahedra that share corners with six equivalent Mg(1)Cd6 cuboctahedra, corners with six equivalent Cd(2)Mg2Cd10 cuboctahedra, corners with six equivalent Cd(1)Mg4Cd8 cuboctahedra, edges with seven equivalent Mg(1)Cd6 cuboctahedra, edges with seven equivalent Cd(2)Mg2Cd10 cuboctahedra, edges with eight equivalent Cd(1)Mg4Cd8 cuboctahedra, faces with six equivalent Cd(2)Mg2Cd10 cuboctahedra, and faces with six equivalent Cd(1)Mg4Cd8 cuboctahedra. In the second Cd site, Cd(2) is bonded to two equivalent Mg(1), four equivalent Cd(2), and six equivalent Cd(1) atoms to form distorted CdMg2Cd10 cuboctahedra that share corners with six equivalent Cd(2)Mg2Cd10 cuboctahedra, corners with six equivalent Cd(1)Mg4Cd8 cuboctahedra, corners with twelve equivalent Mg(1)Cd6 cuboctahedra, edges with seven equivalent Mg(1)Cd6 cuboctahedra, edges with seven equivalent Cd(1)Mg4Cd8 cuboctahedra, faces with two equivalent Mg(1)Cd6 cuboctahedra, faces with six equivalent Cd(1)Mg4Cd8 cuboctahedra, and faces with ten equivalent Cd(2)Mg2Cd10 cuboctahedra.
MgCd2 crystallizes in the orthorhombic Cmcm space group. Mg(1) is bonded to two equivalent Cd(2) and four equivalent Cd(1) atoms to form distorted MgCd6 cuboctahedra that share corners with two equivalent Mg(1)Cd6 cuboctahedra, corners with six equivalent Cd(1)Mg4Cd8 cuboctahedra, corners with twelve equivalent Cd(2)Mg2Cd10 cuboctahedra, edges with six equivalent Mg(1)Cd6 cuboctahedra, edges with seven equivalent Cd(2)Mg2Cd10 cuboctahedra, edges with seven equivalent Cd(1)Mg4Cd8 cuboctahedra, and faces with two equivalent Cd(2)Mg2Cd10 cuboctahedra. Both Mg(1)-Cd(2) bond lengths are 3.06 Å. All Mg(1)-Cd(1) bond lengths are 3.04 Å. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to four equivalent Mg(1), two equivalent Cd(1), and six equivalent Cd(2) atoms to form distorted CdMg4Cd8 cuboctahedra that share corners with six equivalent Mg(1)Cd6 cuboctahedra, corners with six equivalent Cd(2)Mg2Cd10 cuboctahedra, corners with six equivalent Cd(1)Mg4Cd8 cuboctahedra, edges with seven equivalent Mg(1)Cd6 cuboctahedra, edges with seven equivalent Cd(2)Mg2Cd10 cuboctahedra, edges with eight equivalent Cd(1)Mg4Cd8 cuboctahedra, faces with six equivalent Cd(2)Mg2Cd10 cuboctahedra, and faces with six equivalent Cd(1)Mg4Cd8 cuboctahedra. Both Cd(1)-Cd(1) bond lengths are 3.19 Å. There are two shorter (3.11 Å) and four longer (3.17 Å) Cd(1)-Cd(2) bond lengths. In the second Cd site, Cd(2) is bonded to two equivalent Mg(1), four equivalent Cd(2), and six equivalent Cd(1) atoms to form distorted CdMg2Cd10 cuboctahedra that share corners with six equivalent Cd(2)Mg2Cd10 cuboctahedra, corners with six equivalent Cd(1)Mg4Cd8 cuboctahedra, corners with twelve equivalent Mg(1)Cd6 cuboctahedra, edges with seven equivalent Mg(1)Cd6 cuboctahedra, edges with seven equivalent Cd(1)Mg4Cd8 cuboctahedra, faces with two equivalent Mg(1)Cd6 cuboctahedra, faces with six equivalent Cd(1)Mg4Cd8 cuboctahedra, and faces with ten equivalent Cd(2)Mg2Cd10 cuboctahedra. There are two shorter (3.07 Å) and two longer (3.19 Å) Cd(2)-Cd(2) bond lengths.