La2Mg17 crystallizes in the hexagonal P6_3/mmc space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), four equivalent Mg(4), one La(1), and two equivalent La(2) atoms. In the second Mg site, Mg(2) is bonded in a 14-coordinate geometry to one Mg(2), three equivalent Mg(1), three equivalent Mg(3), six equivalent Mg(4), and one La(1) atom. In the third Mg site, Mg(3) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(4), and two equivalent La(1) atoms to form a mixture of distorted edge, face, and corner-sharing MgLa2Mg10 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), four equivalent Mg(1), one La(1), and one La(2) atom to form a mixture of distorted edge, face, and corner-sharing MgLa2Mg10 cuboctahedra. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 20-coordinate geometry to two equivalent Mg(2), six equivalent Mg(1), six equivalent Mg(3), and six equivalent Mg(4) atoms. In the second La site, La(2) is bonded in a 18-coordinate geometry to six equivalent Mg(4) and twelve equivalent Mg(1) atoms.
La2Mg17 crystallizes in the hexagonal P6_3/mmc space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), four equivalent Mg(4), one La(1), and two equivalent La(2) atoms. The Mg(1)-Mg(2) bond length is 3.30 Å. Both Mg(1)-Mg(1) bond lengths are 2.94 Å. Both Mg(1)-Mg(3) bond lengths are 3.02 Å. There are two shorter (3.10 Å) and two longer (3.16 Å) Mg(1)-Mg(4) bond lengths. The Mg(1)-La(1) bond length is 3.83 Å. There is one shorter (3.72 Å) and one longer (4.00 Å) Mg(1)-La(2) bond length. In the second Mg site, Mg(2) is bonded in a 14-coordinate geometry to one Mg(2), three equivalent Mg(1), three equivalent Mg(3), six equivalent Mg(4), and one La(1) atom. The Mg(2)-Mg(2) bond length is 3.01 Å. All Mg(2)-Mg(3) bond lengths are 3.15 Å. All Mg(2)-Mg(4) bond lengths are 3.44 Å. The Mg(2)-La(1) bond length is 3.57 Å. In the third Mg site, Mg(3) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(4), and two equivalent La(1) atoms to form a mixture of distorted edge, face, and corner-sharing MgLa2Mg10 cuboctahedra. All Mg(3)-Mg(4) bond lengths are 3.01 Å. Both Mg(3)-La(1) bond lengths are 3.91 Å. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), four equivalent Mg(1), one La(1), and one La(2) atom to form a mixture of distorted edge, face, and corner-sharing MgLa2Mg10 cuboctahedra. There is one shorter (3.02 Å) and one longer (3.17 Å) Mg(4)-Mg(4) bond length. The Mg(4)-La(1) bond length is 3.66 Å. The Mg(4)-La(2) bond length is 3.58 Å. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 20-coordinate geometry to two equivalent Mg(2), six equivalent Mg(1), six equivalent Mg(3), and six equivalent Mg(4) atoms. In the second La site, La(2) is bonded in a 18-coordinate geometry to six equivalent Mg(4) and twelve equivalent Mg(1) atoms.