MgLa5 crystallizes in the hexagonal P-62m space group. Mg(1) is bonded to six equivalent La(1) and six equivalent La(2) atoms to form MgLa12 cuboctahedra that share corners with eighteen equivalent La(1)La9Mg3 cuboctahedra, edges with six equivalent Mg(1)La12 cuboctahedra, edges with twelve equivalent La(2)La10Mg2 cuboctahedra, faces with two equivalent Mg(1)La12 cuboctahedra, faces with six equivalent La(1)La9Mg3 cuboctahedra, and faces with twelve equivalent La(2)La10Mg2 cuboctahedra. There are two inequivalent La sites. In the first La site, La(1) is bonded to three equivalent Mg(1), three equivalent La(1), and six equivalent La(2) atoms to form LaLa9Mg3 cuboctahedra that share corners with nine equivalent Mg(1)La12 cuboctahedra, corners with nine equivalent La(1)La9Mg3 cuboctahedra, edges with six equivalent La(1)La9Mg3 cuboctahedra, edges with twelve equivalent La(2)La10Mg2 cuboctahedra, faces with three equivalent Mg(1)La12 cuboctahedra, faces with five equivalent La(1)La9Mg3 cuboctahedra, and faces with twelve equivalent La(2)La10Mg2 cuboctahedra. In the second La site, La(2) is bonded to two equivalent Mg(1), four equivalent La(1), and six equivalent La(2) atoms to form distorted LaLa10Mg2 cuboctahedra that share corners with eighteen equivalent La(2)La10Mg2 cuboctahedra, edges with four equivalent Mg(1)La12 cuboctahedra, edges with six equivalent La(2)La10Mg2 cuboctahedra, edges with eight equivalent La(1)La9Mg3 cuboctahedra, faces with four equivalent Mg(1)La12 cuboctahedra, faces with eight equivalent La(2)La10Mg2 cuboctahedra, and faces with eight equivalent La(1)La9Mg3 cuboctahedra.
MgLa5 crystallizes in the hexagonal P-62m space group. Mg(1) is bonded to six equivalent La(1) and six equivalent La(2) atoms to form MgLa12 cuboctahedra that share corners with eighteen equivalent La(1)La9Mg3 cuboctahedra, edges with six equivalent Mg(1)La12 cuboctahedra, edges with twelve equivalent La(2)La10Mg2 cuboctahedra, faces with two equivalent Mg(1)La12 cuboctahedra, faces with six equivalent La(1)La9Mg3 cuboctahedra, and faces with twelve equivalent La(2)La10Mg2 cuboctahedra. All Mg(1)-La(1) bond lengths are 3.71 Å. All Mg(1)-La(2) bond lengths are 3.54 Å. There are two inequivalent La sites. In the first La site, La(1) is bonded to three equivalent Mg(1), three equivalent La(1), and six equivalent La(2) atoms to form LaLa9Mg3 cuboctahedra that share corners with nine equivalent Mg(1)La12 cuboctahedra, corners with nine equivalent La(1)La9Mg3 cuboctahedra, edges with six equivalent La(1)La9Mg3 cuboctahedra, edges with twelve equivalent La(2)La10Mg2 cuboctahedra, faces with three equivalent Mg(1)La12 cuboctahedra, faces with five equivalent La(1)La9Mg3 cuboctahedra, and faces with twelve equivalent La(2)La10Mg2 cuboctahedra. All La(1)-La(1) bond lengths are 3.71 Å. All La(1)-La(2) bond lengths are 3.66 Å. In the second La site, La(2) is bonded to two equivalent Mg(1), four equivalent La(1), and six equivalent La(2) atoms to form distorted LaLa10Mg2 cuboctahedra that share corners with eighteen equivalent La(2)La10Mg2 cuboctahedra, edges with four equivalent Mg(1)La12 cuboctahedra, edges with six equivalent La(2)La10Mg2 cuboctahedra, edges with eight equivalent La(1)La9Mg3 cuboctahedra, faces with four equivalent Mg(1)La12 cuboctahedra, faces with eight equivalent La(2)La10Mg2 cuboctahedra, and faces with eight equivalent La(1)La9Mg3 cuboctahedra. There are two shorter (3.47 Å) and four longer (3.84 Å) La(2)-La(2) bond lengths.