Mg3Bi is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted square co-planar geometry to eight equivalent Mg(2) and four equivalent Bi(1) atoms. In the second Mg site, Mg(2) is bonded to four equivalent Mg(1), four equivalent Mg(2), and four equivalent Bi(1) atoms to form distorted MgMg8Bi4 cuboctahedra that share corners with twelve equivalent Mg(2)Mg8Bi4 cuboctahedra, edges with eight equivalent Mg(2)Mg8Bi4 cuboctahedra, edges with eight equivalent Bi(1)Mg12 cuboctahedra, faces with four equivalent Bi(1)Mg12 cuboctahedra, and faces with ten equivalent Mg(2)Mg8Bi4 cuboctahedra. Bi(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form BiMg12 cuboctahedra that share corners with four equivalent Bi(1)Mg12 cuboctahedra, edges with eight equivalent Bi(1)Mg12 cuboctahedra, edges with sixteen equivalent Mg(2)Mg8Bi4 cuboctahedra, faces with four equivalent Bi(1)Mg12 cuboctahedra, and faces with eight equivalent Mg(2)Mg8Bi4 cuboctahedra.
Mg3Bi is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted square co-planar geometry to eight equivalent Mg(2) and four equivalent Bi(1) atoms. All Mg(1)-Mg(2) bond lengths are 3.29 Å. All Mg(1)-Bi(1) bond lengths are 3.16 Å. In the second Mg site, Mg(2) is bonded to four equivalent Mg(1), four equivalent Mg(2), and four equivalent Bi(1) atoms to form distorted MgMg8Bi4 cuboctahedra that share corners with twelve equivalent Mg(2)Mg8Bi4 cuboctahedra, edges with eight equivalent Mg(2)Mg8Bi4 cuboctahedra, edges with eight equivalent Bi(1)Mg12 cuboctahedra, faces with four equivalent Bi(1)Mg12 cuboctahedra, and faces with ten equivalent Mg(2)Mg8Bi4 cuboctahedra. All Mg(2)-Mg(2) bond lengths are 3.16 Å. All Mg(2)-Bi(1) bond lengths are 3.29 Å. Bi(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form BiMg12 cuboctahedra that share corners with four equivalent Bi(1)Mg12 cuboctahedra, edges with eight equivalent Bi(1)Mg12 cuboctahedra, edges with sixteen equivalent Mg(2)Mg8Bi4 cuboctahedra, faces with four equivalent Bi(1)Mg12 cuboctahedra, and faces with eight equivalent Mg(2)Mg8Bi4 cuboctahedra.