La(Mg2Al)4 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), four equivalent Mg(2), two equivalent La(1), and four equivalent Al(1) atoms. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to one Mg(2), four equivalent Mg(1), one La(1), and four equivalent Al(1) atoms. La(1) is bonded in a 20-coordinate geometry to four equivalent Mg(2), eight equivalent Mg(1), and eight equivalent Al(1) atoms. Al(1) 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.
La(Mg2Al)4 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), four equivalent Mg(2), two equivalent La(1), and four equivalent Al(1) atoms. Both Mg(1)-Mg(1) bond lengths are 3.01 Å. There are two shorter (3.18 Å) and two longer (3.20 Å) Mg(1)-Mg(2) bond lengths. Both Mg(1)-La(1) bond lengths are 3.61 Å. All Mg(1)-Al(1) bond lengths are 2.88 Å. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to one Mg(2), four equivalent Mg(1), one La(1), and four equivalent Al(1) atoms. The Mg(2)-Mg(2) bond length is 2.99 Å. The Mg(2)-La(1) bond length is 3.43 Å. All Mg(2)-Al(1) bond lengths are 3.02 Å. La(1) is bonded in a 20-coordinate geometry to four equivalent Mg(2), eight equivalent Mg(1), and eight equivalent Al(1) atoms. All La(1)-Al(1) bond lengths are 3.78 Å. Al(1) 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 Al(1)-Al(1) bond lengths are 2.92 Å.