MgCd3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Mg(1) is bonded to twelve equivalent Cd(1) atoms to form MgCd12 cuboctahedra that share corners with six equivalent Mg(1)Cd12 cuboctahedra, corners with twelve equivalent Cd(1)Mg4Cd8 cuboctahedra, edges with eighteen equivalent Cd(1)Mg4Cd8 cuboctahedra, faces with eight equivalent Mg(1)Cd12 cuboctahedra, and faces with twelve equivalent Cd(1)Mg4Cd8 cuboctahedra. Cd(1) is bonded to four equivalent Mg(1) and eight equivalent Cd(1) atoms to form distorted CdMg4Cd8 cuboctahedra that share corners with four equivalent Mg(1)Cd12 cuboctahedra, corners with fourteen equivalent Cd(1)Mg4Cd8 cuboctahedra, edges with six equivalent Mg(1)Cd12 cuboctahedra, edges with twelve equivalent Cd(1)Mg4Cd8 cuboctahedra, faces with four equivalent Mg(1)Cd12 cuboctahedra, and faces with sixteen equivalent Cd(1)Mg4Cd8 cuboctahedra.
MgCd3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Mg(1) is bonded to twelve equivalent Cd(1) atoms to form MgCd12 cuboctahedra that share corners with six equivalent Mg(1)Cd12 cuboctahedra, corners with twelve equivalent Cd(1)Mg4Cd8 cuboctahedra, edges with eighteen equivalent Cd(1)Mg4Cd8 cuboctahedra, faces with eight equivalent Mg(1)Cd12 cuboctahedra, and faces with twelve equivalent Cd(1)Mg4Cd8 cuboctahedra. There are six shorter (3.04 Å) and six longer (3.17 Å) Mg(1)-Cd(1) bond lengths. Cd(1) is bonded to four equivalent Mg(1) and eight equivalent Cd(1) atoms to form distorted CdMg4Cd8 cuboctahedra that share corners with four equivalent Mg(1)Cd12 cuboctahedra, corners with fourteen equivalent Cd(1)Mg4Cd8 cuboctahedra, edges with six equivalent Mg(1)Cd12 cuboctahedra, edges with twelve equivalent Cd(1)Mg4Cd8 cuboctahedra, faces with four equivalent Mg(1)Cd12 cuboctahedra, and faces with sixteen equivalent Cd(1)Mg4Cd8 cuboctahedra. There are a spread of Cd(1)-Cd(1) bond distances ranging from 3.04-3.17 Å.