BaMg7 crystallizes in the hexagonal P-6m2 space group. Ba(1) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form BaMg12 cuboctahedra that share corners with six equivalent Ba(1)Mg12 cuboctahedra, faces with two equivalent Ba(1)Mg12 cuboctahedra, and faces with six equivalent Mg(3)Mg12 cuboctahedra. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to two equivalent Ba(1), two equivalent Mg(1), two equivalent Mg(3), and four equivalent Mg(2) atoms. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Ba(1), two equivalent Mg(2), two equivalent Mg(3), and four equivalent Mg(1) atoms. In the third Mg site, Mg(3) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form distorted MgMg12 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg12 cuboctahedra, and faces with six equivalent Ba(1)Mg12 cuboctahedra.
BaMg7 crystallizes in the hexagonal P-6m2 space group. Ba(1) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form BaMg12 cuboctahedra that share corners with six equivalent Ba(1)Mg12 cuboctahedra, faces with two equivalent Ba(1)Mg12 cuboctahedra, and faces with six equivalent Mg(3)Mg12 cuboctahedra. All Ba(1)-Mg(1) bond lengths are 3.47 Å. All Ba(1)-Mg(2) bond lengths are 3.42 Å. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to two equivalent Ba(1), two equivalent Mg(1), two equivalent Mg(3), and four equivalent Mg(2) atoms. Both Mg(1)-Mg(1) bond lengths are 3.35 Å. Both Mg(1)-Mg(3) bond lengths are 3.37 Å. All Mg(1)-Mg(2) bond lengths are 3.26 Å. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Ba(1), two equivalent Mg(2), two equivalent Mg(3), and four equivalent Mg(1) atoms. Both Mg(2)-Mg(2) bond lengths are 3.19 Å. Both Mg(2)-Mg(3) bond lengths are 3.48 Å. In the third Mg site, Mg(3) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form distorted MgMg12 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg12 cuboctahedra, and faces with six equivalent Ba(1)Mg12 cuboctahedra.