MgSm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. Mg(1) is bonded to four equivalent Sm(1) and eight equivalent Sm(2) atoms to form MgSm12 cuboctahedra that share corners with four equivalent Mg(1)Sm12 cuboctahedra, corners with eight equivalent Sm(1)Sm8Mg4 cuboctahedra, edges with eight equivalent Mg(1)Sm12 cuboctahedra, edges with sixteen equivalent Sm(2)Sm8Mg4 cuboctahedra, faces with four equivalent Mg(1)Sm12 cuboctahedra, faces with six equivalent Sm(1)Sm8Mg4 cuboctahedra, and faces with eight equivalent Sm(2)Sm8Mg4 cuboctahedra. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to four equivalent Mg(1) and eight equivalent Sm(2) atoms to form SmSm8Mg4 cuboctahedra that share corners with four equivalent Sm(1)Sm8Mg4 cuboctahedra, corners with eight equivalent Mg(1)Sm12 cuboctahedra, edges with eight equivalent Sm(1)Sm8Mg4 cuboctahedra, edges with sixteen equivalent Sm(2)Sm8Mg4 cuboctahedra, faces with four equivalent Sm(1)Sm8Mg4 cuboctahedra, faces with six equivalent Mg(1)Sm12 cuboctahedra, and faces with eight equivalent Sm(2)Sm8Mg4 cuboctahedra. In the second Sm site, Sm(2) is bonded to four equivalent Mg(1), four equivalent Sm(1), and four equivalent Sm(2) atoms to form SmSm8Mg4 cuboctahedra that share corners with twelve equivalent Sm(2)Sm8Mg4 cuboctahedra, edges with eight equivalent Mg(1)Sm12 cuboctahedra, edges with eight equivalent Sm(1)Sm8Mg4 cuboctahedra, edges with eight equivalent Sm(2)Sm8Mg4 cuboctahedra, faces with four equivalent Mg(1)Sm12 cuboctahedra, faces with four equivalent Sm(1)Sm8Mg4 cuboctahedra, and faces with ten equivalent Sm(2)Sm8Mg4 cuboctahedra.
MgSm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. Mg(1) is bonded to four equivalent Sm(1) and eight equivalent Sm(2) atoms to form MgSm12 cuboctahedra that share corners with four equivalent Mg(1)Sm12 cuboctahedra, corners with eight equivalent Sm(1)Sm8Mg4 cuboctahedra, edges with eight equivalent Mg(1)Sm12 cuboctahedra, edges with sixteen equivalent Sm(2)Sm8Mg4 cuboctahedra, faces with four equivalent Mg(1)Sm12 cuboctahedra, faces with six equivalent Sm(1)Sm8Mg4 cuboctahedra, and faces with eight equivalent Sm(2)Sm8Mg4 cuboctahedra. All Mg(1)-Sm(1) bond lengths are 3.51 Å. All Mg(1)-Sm(2) bond lengths are 3.52 Å. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to four equivalent Mg(1) and eight equivalent Sm(2) atoms to form SmSm8Mg4 cuboctahedra that share corners with four equivalent Sm(1)Sm8Mg4 cuboctahedra, corners with eight equivalent Mg(1)Sm12 cuboctahedra, edges with eight equivalent Sm(1)Sm8Mg4 cuboctahedra, edges with sixteen equivalent Sm(2)Sm8Mg4 cuboctahedra, faces with four equivalent Sm(1)Sm8Mg4 cuboctahedra, faces with six equivalent Mg(1)Sm12 cuboctahedra, and faces with eight equivalent Sm(2)Sm8Mg4 cuboctahedra. All Sm(1)-Sm(2) bond lengths are 3.52 Å. In the second Sm site, Sm(2) is bonded to four equivalent Mg(1), four equivalent Sm(1), and four equivalent Sm(2) atoms to form SmSm8Mg4 cuboctahedra that share corners with twelve equivalent Sm(2)Sm8Mg4 cuboctahedra, edges with eight equivalent Mg(1)Sm12 cuboctahedra, edges with eight equivalent Sm(1)Sm8Mg4 cuboctahedra, edges with eight equivalent Sm(2)Sm8Mg4 cuboctahedra, faces with four equivalent Mg(1)Sm12 cuboctahedra, faces with four equivalent Sm(1)Sm8Mg4 cuboctahedra, and faces with ten equivalent Sm(2)Sm8Mg4 cuboctahedra. All Sm(2)-Sm(2) bond lengths are 3.51 Å.