Mg5Bi crystallizes in the hexagonal P-62m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted water-like geometry to four equivalent Mg(2) and two equivalent Bi(1) atoms. In the second Mg site, Mg(2) is bonded to three equivalent Mg(2), six equivalent Mg(1), and three equivalent Bi(1) atoms to form distorted MgMg9Bi3 cuboctahedra that share corners with nine equivalent Mg(2)Mg9Bi3 cuboctahedra, corners with nine equivalent Bi(1)Mg12 cuboctahedra, edges with six equivalent Mg(2)Mg9Bi3 cuboctahedra, faces with three equivalent Bi(1)Mg12 cuboctahedra, and faces with five equivalent Mg(2)Mg9Bi3 cuboctahedra. Bi(1) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form BiMg12 cuboctahedra that share corners with eighteen equivalent Mg(2)Mg9Bi3 cuboctahedra, edges with six equivalent Bi(1)Mg12 cuboctahedra, faces with two equivalent Bi(1)Mg12 cuboctahedra, and faces with six equivalent Mg(2)Mg9Bi3 cuboctahedra.
Mg5Bi crystallizes in the hexagonal P-62m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted water-like geometry to four equivalent Mg(2) and two equivalent Bi(1) atoms. All Mg(1)-Mg(2) bond lengths are 3.16 Å. Both Mg(1)-Bi(1) bond lengths are 3.23 Å. In the second Mg site, Mg(2) is bonded to three equivalent Mg(2), six equivalent Mg(1), and three equivalent Bi(1) atoms to form distorted MgMg9Bi3 cuboctahedra that share corners with nine equivalent Mg(2)Mg9Bi3 cuboctahedra, corners with nine equivalent Bi(1)Mg12 cuboctahedra, edges with six equivalent Mg(2)Mg9Bi3 cuboctahedra, faces with three equivalent Bi(1)Mg12 cuboctahedra, and faces with five equivalent Mg(2)Mg9Bi3 cuboctahedra. All Mg(2)-Mg(2) bond lengths are 3.36 Å. All Mg(2)-Bi(1) bond lengths are 3.36 Å. Bi(1) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form BiMg12 cuboctahedra that share corners with eighteen equivalent Mg(2)Mg9Bi3 cuboctahedra, edges with six equivalent Bi(1)Mg12 cuboctahedra, faces with two equivalent Bi(1)Mg12 cuboctahedra, and faces with six equivalent Mg(2)Mg9Bi3 cuboctahedra.