MgCd3 crystallizes in the orthorhombic Pmm2 space group. Mg(1) is bonded to two equivalent Cd(1), four equivalent Cd(2), and four equivalent Cd(3) atoms to form distorted MgCd10 cuboctahedra that share corners with four equivalent Cd(2)Mg4Cd8 cuboctahedra, corners with eight equivalent Mg(1)Cd10 cuboctahedra, corners with twelve equivalent Cd(3)Mg4Cd8 cuboctahedra, edges with two equivalent Mg(1)Cd10 cuboctahedra, edges with four equivalent Cd(1)Mg2Cd10 cuboctahedra, edges with four equivalent Cd(2)Mg4Cd8 cuboctahedra, faces with four equivalent Mg(1)Cd10 cuboctahedra, faces with four equivalent Cd(2)Mg4Cd8 cuboctahedra, faces with four equivalent Cd(3)Mg4Cd8 cuboctahedra, and faces with eight equivalent Cd(1)Mg2Cd10 cuboctahedra. There are three inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to two equivalent Mg(1), two equivalent Cd(1), four equivalent Cd(2), and four equivalent Cd(3) atoms to form distorted CdMg2Cd10 cuboctahedra that share corners with eight equivalent Cd(2)Mg4Cd8 cuboctahedra, corners with ten equivalent Cd(1)Mg2Cd10 cuboctahedra, edges with two equivalent Cd(1)Mg2Cd10 cuboctahedra, edges with four equivalent Mg(1)Cd10 cuboctahedra, edges with four equivalent Cd(2)Mg4Cd8 cuboctahedra, edges with eight equivalent Cd(3)Mg4Cd8 cuboctahedra, faces with four equivalent Cd(1)Mg2Cd10 cuboctahedra, faces with four equivalent Cd(2)Mg4Cd8 cuboctahedra, faces with four equivalent Cd(3)Mg4Cd8 cuboctahedra, and faces with eight equivalent Mg(1)Cd10 cuboctahedra. In the second Cd site, Cd(2) is bonded to four equivalent Mg(1), two equivalent Cd(2), two equivalent Cd(3), and four equivalent Cd(1) atoms to form distorted CdMg4Cd8 cuboctahedra that share corners with four equivalent Mg(1)Cd10 cuboctahedra, corners with eight equivalent Cd(1)Mg2Cd10 cuboctahedra, corners with ten equivalent Cd(2)Mg4Cd8 cuboctahedra, edges with two equivalent Cd(2)Mg4Cd8 cuboctahedra, edges with four equivalent Mg(1)Cd10 cuboctahedra, edges with four equivalent Cd(1)Mg2Cd10 cuboctahedra, edges with four equivalent Cd(3)Mg4Cd8 cuboctahedra, faces with four equivalent Mg(1)Cd10 cuboctahedra, faces with four equivalent Cd(1)Mg2Cd10 cuboctahedra, faces with four equivalent Cd(2)Mg4Cd8 cuboctahedra, and faces with eight equivalent Cd(3)Mg4Cd8 cuboctahedra. In the third Cd site, Cd(3) is bonded to four equivalent Mg(1), two equivalent Cd(2), two equivalent Cd(3), and four equivalent Cd(1) atoms to form distorted CdMg4Cd8 cuboctahedra that share corners with ten equivalent Cd(3)Mg4Cd8 cuboctahedra, corners with twelve equivalent Mg(1)Cd10 cuboctahedra, edges with two equivalent Cd(3)Mg4Cd8 cuboctahedra, edges with four equivalent Cd(2)Mg4Cd8 cuboctahedra, edges with eight equivalent Cd(1)Mg2Cd10 cuboctahedra, faces with four equivalent Mg(1)Cd10 cuboctahedra, faces with four equivalent Cd(1)Mg2Cd10 cuboctahedra, faces with four equivalent Cd(3)Mg4Cd8 cuboctahedra, and faces with eight equivalent Cd(2)Mg4Cd8 cuboctahedra.
MgCd3 crystallizes in the orthorhombic Pmm2 space group. Mg(1) is bonded to two equivalent Cd(1), four equivalent Cd(2), and four equivalent Cd(3) atoms to form distorted MgCd10 cuboctahedra that share corners with four equivalent Cd(2)Mg4Cd8 cuboctahedra, corners with eight equivalent Mg(1)Cd10 cuboctahedra, corners with twelve equivalent Cd(3)Mg4Cd8 cuboctahedra, edges with two equivalent Mg(1)Cd10 cuboctahedra, edges with four equivalent Cd(1)Mg2Cd10 cuboctahedra, edges with four equivalent Cd(2)Mg4Cd8 cuboctahedra, faces with four equivalent Mg(1)Cd10 cuboctahedra, faces with four equivalent Cd(2)Mg4Cd8 cuboctahedra, faces with four equivalent Cd(3)Mg4Cd8 cuboctahedra, and faces with eight equivalent Cd(1)Mg2Cd10 cuboctahedra. Both Mg(1)-Cd(1) bond lengths are 3.04 Å. All Mg(1)-Cd(2) bond lengths are 3.09 Å. There are two shorter (3.08 Å) and two longer (3.13 Å) Mg(1)-Cd(3) bond lengths. There are three inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to two equivalent Mg(1), two equivalent Cd(1), four equivalent Cd(2), and four equivalent Cd(3) atoms to form distorted CdMg2Cd10 cuboctahedra that share corners with eight equivalent Cd(2)Mg4Cd8 cuboctahedra, corners with ten equivalent Cd(1)Mg2Cd10 cuboctahedra, edges with two equivalent Cd(1)Mg2Cd10 cuboctahedra, edges with four equivalent Mg(1)Cd10 cuboctahedra, edges with four equivalent Cd(2)Mg4Cd8 cuboctahedra, edges with eight equivalent Cd(3)Mg4Cd8 cuboctahedra, faces with four equivalent Cd(1)Mg2Cd10 cuboctahedra, faces with four equivalent Cd(2)Mg4Cd8 cuboctahedra, faces with four equivalent Cd(3)Mg4Cd8 cuboctahedra, and faces with eight equivalent Mg(1)Cd10 cuboctahedra. Both Cd(1)-Cd(1) bond lengths are 3.23 Å. There are two shorter (3.08 Å) and two longer (3.13 Å) Cd(1)-Cd(2) bond lengths. All Cd(1)-Cd(3) bond lengths are 3.10 Å. In the second Cd site, Cd(2) is bonded to four equivalent Mg(1), two equivalent Cd(2), two equivalent Cd(3), and four equivalent Cd(1) atoms to form distorted CdMg4Cd8 cuboctahedra that share corners with four equivalent Mg(1)Cd10 cuboctahedra, corners with eight equivalent Cd(1)Mg2Cd10 cuboctahedra, corners with ten equivalent Cd(2)Mg4Cd8 cuboctahedra, edges with two equivalent Cd(2)Mg4Cd8 cuboctahedra, edges with four equivalent Mg(1)Cd10 cuboctahedra, edges with four equivalent Cd(1)Mg2Cd10 cuboctahedra, edges with four equivalent Cd(3)Mg4Cd8 cuboctahedra, faces with four equivalent Mg(1)Cd10 cuboctahedra, faces with four equivalent Cd(1)Mg2Cd10 cuboctahedra, faces with four equivalent Cd(2)Mg4Cd8 cuboctahedra, and faces with eight equivalent Cd(3)Mg4Cd8 cuboctahedra. Both Cd(2)-Cd(2) bond lengths are 3.23 Å. Both Cd(2)-Cd(3) bond lengths are 3.05 Å. In the third Cd site, Cd(3) is bonded to four equivalent Mg(1), two equivalent Cd(2), two equivalent Cd(3), and four equivalent Cd(1) atoms to form distorted CdMg4Cd8 cuboctahedra that share corners with ten equivalent Cd(3)Mg4Cd8 cuboctahedra, corners with twelve equivalent Mg(1)Cd10 cuboctahedra, edges with two equivalent Cd(3)Mg4Cd8 cuboctahedra, edges with four equivalent Cd(2)Mg4Cd8 cuboctahedra, edges with eight equivalent Cd(1)Mg2Cd10 cuboctahedra, faces with four equivalent Mg(1)Cd10 cuboctahedra, faces with four equivalent Cd(1)Mg2Cd10 cuboctahedra, faces with four equivalent Cd(3)Mg4Cd8 cuboctahedra, and faces with eight equivalent Cd(2)Mg4Cd8 cuboctahedra. Both Cd(3)-Cd(3) bond lengths are 3.23 Å.