Mg11LaAl crystallizes in the monoclinic C2/m space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 1-coordinate geometry to one Mg(3), two equivalent Mg(4), four equivalent Mg(2), two equivalent La(1), and one Al(1) atom. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to one Mg(2), one Mg(3), two equivalent Mg(4), four equivalent Mg(1), one La(1), and one Al(1) atom. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to four equivalent Mg(1), four equivalent Mg(2), two equivalent La(1), and two equivalent Al(1) atoms. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent La(1) atoms to form a mixture of distorted corner and face-sharing MgLa2Mg10 cuboctahedra. La(1) is bonded in a 20-coordinate geometry to two equivalent Mg(3), four equivalent Mg(2), four equivalent Mg(4), eight equivalent Mg(1), and two equivalent Al(1) atoms. Al(1) is bonded in a 10-coordinate geometry to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent La(1) atoms.
Mg11LaAl crystallizes in the monoclinic C2/m space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 1-coordinate geometry to one Mg(3), two equivalent Mg(4), four equivalent Mg(2), two equivalent La(1), and one Al(1) atom. The Mg(1)-Mg(3) bond length is 2.95 Å. Both Mg(1)-Mg(4) bond lengths are 2.99 Å. There are a spread of Mg(1)-Mg(2) bond distances ranging from 3.20-3.33 Å. There is one shorter (3.71 Å) and one longer (3.72 Å) Mg(1)-La(1) bond length. The Mg(1)-Al(1) bond length is 2.92 Å. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to one Mg(2), one Mg(3), two equivalent Mg(4), four equivalent Mg(1), one La(1), and one Al(1) atom. The Mg(2)-Mg(2) bond length is 3.05 Å. The Mg(2)-Mg(3) bond length is 3.10 Å. There is one shorter (3.11 Å) and one longer (3.14 Å) Mg(2)-Mg(4) bond length. The Mg(2)-La(1) bond length is 3.54 Å. The Mg(2)-Al(1) bond length is 3.10 Å. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to four equivalent Mg(1), four equivalent Mg(2), two equivalent La(1), and two equivalent Al(1) atoms. Both Mg(3)-La(1) bond lengths are 3.84 Å. Both Mg(3)-Al(1) bond lengths are 3.01 Å. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent La(1) atoms to form a mixture of distorted corner and face-sharing MgLa2Mg10 cuboctahedra. Both Mg(4)-Mg(4) bond lengths are 3.01 Å. Both Mg(4)-La(1) bond lengths are 3.91 Å. La(1) is bonded in a 20-coordinate geometry to two equivalent Mg(3), four equivalent Mg(2), four equivalent Mg(4), eight equivalent Mg(1), and two equivalent Al(1) atoms. Both La(1)-Al(1) bond lengths are 3.87 Å. Al(1) is bonded in a 10-coordinate geometry to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent La(1) atoms.