MgLa3 crystallizes in the orthorhombic Pmm2 space group. Mg(1) is bonded in a distorted q6 geometry to two equivalent La(1), four equivalent La(2), and four equivalent La(3) atoms. There are three inequivalent La sites. In the first La site, La(1) is bonded to two equivalent Mg(1), two equivalent La(1), four equivalent La(2), and four equivalent La(3) atoms to form distorted LaLa10Mg2 cuboctahedra that share corners with eight equivalent La(2)La8Mg4 cuboctahedra, corners with ten equivalent La(1)La10Mg2 cuboctahedra, edges with two equivalent La(1)La10Mg2 cuboctahedra, edges with four equivalent La(2)La8Mg4 cuboctahedra, edges with eight equivalent La(3)La8Mg4 cuboctahedra, faces with four equivalent La(1)La10Mg2 cuboctahedra, faces with four equivalent La(2)La8Mg4 cuboctahedra, and faces with four equivalent La(3)La8Mg4 cuboctahedra. In the second La site, La(2) is bonded to four equivalent Mg(1), two equivalent La(2), two equivalent La(3), and four equivalent La(1) atoms to form distorted LaLa8Mg4 cuboctahedra that share corners with eight equivalent La(1)La10Mg2 cuboctahedra, corners with ten equivalent La(2)La8Mg4 cuboctahedra, edges with two equivalent La(2)La8Mg4 cuboctahedra, edges with four equivalent La(1)La10Mg2 cuboctahedra, edges with four equivalent La(3)La8Mg4 cuboctahedra, faces with four equivalent La(1)La10Mg2 cuboctahedra, faces with four equivalent La(2)La8Mg4 cuboctahedra, and faces with eight equivalent La(3)La8Mg4 cuboctahedra. In the third La site, La(3) is bonded to four equivalent Mg(1), two equivalent La(2), two equivalent La(3), and four equivalent La(1) atoms to form distorted LaLa8Mg4 cuboctahedra that share corners with ten equivalent La(3)La8Mg4 cuboctahedra, edges with two equivalent La(3)La8Mg4 cuboctahedra, edges with four equivalent La(2)La8Mg4 cuboctahedra, edges with eight equivalent La(1)La10Mg2 cuboctahedra, faces with four equivalent La(1)La10Mg2 cuboctahedra, faces with four equivalent La(3)La8Mg4 cuboctahedra, and faces with eight equivalent La(2)La8Mg4 cuboctahedra.
MgLa3 crystallizes in the orthorhombic Pmm2 space group. Mg(1) is bonded in a distorted q6 geometry to two equivalent La(1), four equivalent La(2), and four equivalent La(3) atoms. Both Mg(1)-La(1) bond lengths are 3.54 Å. All Mg(1)-La(2) bond lengths are 3.52 Å. There are two shorter (3.49 Å) and two longer (3.70 Å) Mg(1)-La(3) bond lengths. There are three inequivalent La sites. In the first La site, La(1) is bonded to two equivalent Mg(1), two equivalent La(1), four equivalent La(2), and four equivalent La(3) atoms to form distorted LaLa10Mg2 cuboctahedra that share corners with eight equivalent La(2)La8Mg4 cuboctahedra, corners with ten equivalent La(1)La10Mg2 cuboctahedra, edges with two equivalent La(1)La10Mg2 cuboctahedra, edges with four equivalent La(2)La8Mg4 cuboctahedra, edges with eight equivalent La(3)La8Mg4 cuboctahedra, faces with four equivalent La(1)La10Mg2 cuboctahedra, faces with four equivalent La(2)La8Mg4 cuboctahedra, and faces with four equivalent La(3)La8Mg4 cuboctahedra. Both La(1)-La(1) bond lengths are 3.78 Å. There are two shorter (3.29 Å) and two longer (3.91 Å) La(1)-La(2) bond lengths. All La(1)-La(3) bond lengths are 3.57 Å. In the second La site, La(2) is bonded to four equivalent Mg(1), two equivalent La(2), two equivalent La(3), and four equivalent La(1) atoms to form distorted LaLa8Mg4 cuboctahedra that share corners with eight equivalent La(1)La10Mg2 cuboctahedra, corners with ten equivalent La(2)La8Mg4 cuboctahedra, edges with two equivalent La(2)La8Mg4 cuboctahedra, edges with four equivalent La(1)La10Mg2 cuboctahedra, edges with four equivalent La(3)La8Mg4 cuboctahedra, faces with four equivalent La(1)La10Mg2 cuboctahedra, faces with four equivalent La(2)La8Mg4 cuboctahedra, and faces with eight equivalent La(3)La8Mg4 cuboctahedra. Both La(2)-La(2) bond lengths are 3.78 Å. Both La(2)-La(3) bond lengths are 3.84 Å. In the third La site, La(3) is bonded to four equivalent Mg(1), two equivalent La(2), two equivalent La(3), and four equivalent La(1) atoms to form distorted LaLa8Mg4 cuboctahedra that share corners with ten equivalent La(3)La8Mg4 cuboctahedra, edges with two equivalent La(3)La8Mg4 cuboctahedra, edges with four equivalent La(2)La8Mg4 cuboctahedra, edges with eight equivalent La(1)La10Mg2 cuboctahedra, faces with four equivalent La(1)La10Mg2 cuboctahedra, faces with four equivalent La(3)La8Mg4 cuboctahedra, and faces with eight equivalent La(2)La8Mg4 cuboctahedra. Both La(3)-La(3) bond lengths are 3.78 Å.