Mg7Ga crystallizes in the hexagonal P-6m2 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Ga(1) atoms to form distorted MgMg10Ga2 cuboctahedra that share corners with four equivalent Ga(1)Mg12 cuboctahedra, corners with fourteen equivalent Mg(1)Mg10Ga2 cuboctahedra, edges with two equivalent Ga(1)Mg12 cuboctahedra, edges with four equivalent Mg(1)Mg10Ga2 cuboctahedra, edges with four equivalent Mg(3)Mg12 cuboctahedra, edges with eight equivalent Mg(2)Mg10Ga2 cuboctahedra, faces with two equivalent Mg(3)Mg12 cuboctahedra, faces with two equivalent Ga(1)Mg12 cuboctahedra, faces with six equivalent Mg(1)Mg10Ga2 cuboctahedra, and faces with ten equivalent Mg(2)Mg10Ga2 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Ga(1) atoms to form distorted MgMg10Ga2 cuboctahedra that share corners with four equivalent Mg(3)Mg12 cuboctahedra, corners with fourteen equivalent Mg(2)Mg10Ga2 cuboctahedra, edges with two equivalent Mg(3)Mg12 cuboctahedra, edges with four equivalent Mg(2)Mg10Ga2 cuboctahedra, edges with four equivalent Ga(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)Mg10Ga2 cuboctahedra, faces with two equivalent Mg(3)Mg12 cuboctahedra, faces with two equivalent Ga(1)Mg12 cuboctahedra, faces with six equivalent Mg(2)Mg10Ga2 cuboctahedra, and faces with ten equivalent Mg(1)Mg10Ga2 cuboctahedra. In the third Mg site, Mg(3) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra, corners with twelve equivalent Mg(2)Mg10Ga2 cuboctahedra, edges with six equivalent Mg(2)Mg10Ga2 cuboctahedra, edges with twelve equivalent Mg(1)Mg10Ga2 cuboctahedra, faces with two equivalent Mg(3)Mg12 cuboctahedra, faces with six equivalent Mg(1)Mg10Ga2 cuboctahedra, faces with six equivalent Mg(2)Mg10Ga2 cuboctahedra, and faces with six equivalent Ga(1)Mg12 cuboctahedra. Ga(1) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form GaMg12 cuboctahedra that share corners with six equivalent Ga(1)Mg12 cuboctahedra, corners with twelve equivalent Mg(1)Mg10Ga2 cuboctahedra, edges with six equivalent Mg(1)Mg10Ga2 cuboctahedra, edges with twelve equivalent Mg(2)Mg10Ga2 cuboctahedra, faces with two equivalent Ga(1)Mg12 cuboctahedra, faces with six equivalent Mg(1)Mg10Ga2 cuboctahedra, faces with six equivalent Mg(2)Mg10Ga2 cuboctahedra, and faces with six equivalent Mg(3)Mg12 cuboctahedra.
Mg7Ga crystallizes in the hexagonal P-6m2 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Ga(1) atoms to form distorted MgMg10Ga2 cuboctahedra that share corners with four equivalent Ga(1)Mg12 cuboctahedra, corners with fourteen equivalent Mg(1)Mg10Ga2 cuboctahedra, edges with two equivalent Ga(1)Mg12 cuboctahedra, edges with four equivalent Mg(1)Mg10Ga2 cuboctahedra, edges with four equivalent Mg(3)Mg12 cuboctahedra, edges with eight equivalent Mg(2)Mg10Ga2 cuboctahedra, faces with two equivalent Mg(3)Mg12 cuboctahedra, faces with two equivalent Ga(1)Mg12 cuboctahedra, faces with six equivalent Mg(1)Mg10Ga2 cuboctahedra, and faces with ten equivalent Mg(2)Mg10Ga2 cuboctahedra. Both Mg(1)-Mg(3) bond lengths are 3.10 Å. All Mg(1)-Mg(1) bond lengths are 3.13 Å. All Mg(1)-Mg(2) bond lengths are 3.11 Å. Both Mg(1)-Ga(1) bond lengths are 3.13 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Ga(1) atoms to form distorted MgMg10Ga2 cuboctahedra that share corners with four equivalent Mg(3)Mg12 cuboctahedra, corners with fourteen equivalent Mg(2)Mg10Ga2 cuboctahedra, edges with two equivalent Mg(3)Mg12 cuboctahedra, edges with four equivalent Mg(2)Mg10Ga2 cuboctahedra, edges with four equivalent Ga(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)Mg10Ga2 cuboctahedra, faces with two equivalent Mg(3)Mg12 cuboctahedra, faces with two equivalent Ga(1)Mg12 cuboctahedra, faces with six equivalent Mg(2)Mg10Ga2 cuboctahedra, and faces with ten equivalent Mg(1)Mg10Ga2 cuboctahedra. Both Mg(2)-Mg(3) bond lengths are 3.13 Å. There are two shorter (3.10 Å) and two longer (3.15 Å) Mg(2)-Mg(2) bond lengths. Both Mg(2)-Ga(1) bond lengths are 3.09 Å. In the third Mg site, Mg(3) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra, corners with twelve equivalent Mg(2)Mg10Ga2 cuboctahedra, edges with six equivalent Mg(2)Mg10Ga2 cuboctahedra, edges with twelve equivalent Mg(1)Mg10Ga2 cuboctahedra, faces with two equivalent Mg(3)Mg12 cuboctahedra, faces with six equivalent Mg(1)Mg10Ga2 cuboctahedra, faces with six equivalent Mg(2)Mg10Ga2 cuboctahedra, and faces with six equivalent Ga(1)Mg12 cuboctahedra. Ga(1) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form GaMg12 cuboctahedra that share corners with six equivalent Ga(1)Mg12 cuboctahedra, corners with twelve equivalent Mg(1)Mg10Ga2 cuboctahedra, edges with six equivalent Mg(1)Mg10Ga2 cuboctahedra, edges with twelve equivalent Mg(2)Mg10Ga2 cuboctahedra, faces with two equivalent Ga(1)Mg12 cuboctahedra, faces with six equivalent Mg(1)Mg10Ga2 cuboctahedra, faces with six equivalent Mg(2)Mg10Ga2 cuboctahedra, and faces with six equivalent Mg(3)Mg12 cuboctahedra.