RbMg7 crystallizes in the hexagonal P-6m2 space group. Rb(1) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form RbMg12 cuboctahedra that share corners with six equivalent Rb(1)Mg12 cuboctahedra, faces with two equivalent Rb(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 2-coordinate geometry to two equivalent Rb(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 Rb(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 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 Rb(1)Mg12 cuboctahedra.
RbMg7 crystallizes in the hexagonal P-6m2 space group. Rb(1) is bonded to six equivalent Mg(1) and six equivalent Mg(2) atoms to form RbMg12 cuboctahedra that share corners with six equivalent Rb(1)Mg12 cuboctahedra, faces with two equivalent Rb(1)Mg12 cuboctahedra, and faces with six equivalent Mg(3)Mg12 cuboctahedra. All Rb(1)-Mg(1) bond lengths are 3.46 Å. All Rb(1)-Mg(2) bond lengths are 3.47 Å. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 2-coordinate geometry to two equivalent Rb(1), two equivalent Mg(3), and four equivalent Mg(2) atoms. Both Mg(1)-Mg(3) bond lengths are 3.39 Å. All Mg(1)-Mg(2) bond lengths are 3.30 Å. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Rb(1), two equivalent Mg(2), two equivalent Mg(3), and four equivalent Mg(1) atoms. Both Mg(2)-Mg(2) bond lengths are 3.16 Å. Both Mg(2)-Mg(3) bond lengths are 3.47 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, faces with two equivalent Mg(3)Mg12 cuboctahedra, and faces with six equivalent Rb(1)Mg12 cuboctahedra.