Mg14CuAl crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2), two equivalent Mg(6), four equivalent Mg(4), and four equivalent Mg(5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Cu(1)Mg10Al2 cuboctahedra, corners with six equivalent Mg(1)Mg12 cuboctahedra, corners with eight equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with four equivalent Mg(6)Mg11Al cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Al(1)Mg10Cu2 cuboctahedra, and faces with four equivalent Mg(4)Mg12 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(7), four equivalent Mg(4), and four equivalent Mg(5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Al(1)Mg10Cu2 cuboctahedra, corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with eight equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Cu(1)Mg10Al2 cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with six equivalent Mg(6)Mg11Al cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), two equivalent Cu(1), and two equivalent Al(1) atoms to form distorted MgMg8Al2Cu2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra, corners with four equivalent Mg(2)Mg12 cuboctahedra, corners with four equivalent Mg(4)Mg12 cuboctahedra, corners with six equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, edges with two equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, edges with two equivalent Cu(1)Mg10Al2 cuboctahedra, edges with two equivalent Al(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, faces with two equivalent Cu(1)Mg10Al2 cuboctahedra, and faces with two equivalent Al(1)Mg10Cu2 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), and two equivalent Mg(7) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, corners with four equivalent Cu(1)Mg10Al2 cuboctahedra, corners with four equivalent Al(1)Mg10Cu2 cuboctahedra, corners with six equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with two equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, and faces with two equivalent Mg(3)Mg8Al2Cu2 cuboctahedra. In the fifth Mg site, Mg(5) is bonded in a 2-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(6), two equivalent Mg(7), one Cu(1), and one Al(1) atom. In the sixth Mg site, Mg(6) is bonded to one Mg(1), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(7), four equivalent Mg(5), and one Al(1) atom to form distorted MgMg11Al cuboctahedra that share corners with six equivalent Mg(6)Mg11Al cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with two equivalent Al(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra,  a faceface with one Mg(1)Mg12 cuboctahedra,  a faceface with one Al(1)Mg10Cu2 cuboctahedra, faces with two equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, faces with three equivalent Mg(2)Mg12 cuboctahedra, and faces with three equivalent Cu(1)Mg10Al2 cuboctahedra. In the seventh Mg site, Mg(7) is bonded in a distorted single-bond geometry to one Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(6), four equivalent Mg(5), and one Cu(1) atom. Cu(1) is bonded to two equivalent Mg(7), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Al(1) atoms to form CuMg10Al2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra, corners with six equivalent Cu(1)Mg10Al2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Al(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Al(1)Mg10Cu2 cuboctahedra, faces with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, and faces with six equivalent Mg(6)Mg11Al cuboctahedra. Al(1) is bonded to two equivalent Mg(6), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Cu(1) atoms to form AlMg10Cu2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Al(1)Mg10Cu2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Cu(1)Mg10Al2 cuboctahedra, edges with four equivalent Mg(6)Mg11Al cuboctahedra, edges with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, faces with two equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Cu(1)Mg10Al2 cuboctahedra, and faces with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra.
Mg14CuAl crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2), two equivalent Mg(6), four equivalent Mg(4), and four equivalent Mg(5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Cu(1)Mg10Al2 cuboctahedra, corners with six equivalent Mg(1)Mg12 cuboctahedra, corners with eight equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with four equivalent Mg(6)Mg11Al cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Al(1)Mg10Cu2 cuboctahedra, and faces with four equivalent Mg(4)Mg12 cuboctahedra. Both Mg(1)-Mg(2) bond lengths are 3.12 Å. Both Mg(1)-Mg(6) bond lengths are 3.14 Å. There are two shorter (3.10 Å) and two longer (3.13 Å) Mg(1)-Mg(4) bond lengths. All Mg(1)-Mg(5) bond lengths are 3.25 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(7), four equivalent Mg(4), and four equivalent Mg(5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Al(1)Mg10Cu2 cuboctahedra, corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with eight equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Cu(1)Mg10Al2 cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with six equivalent Mg(6)Mg11Al cuboctahedra. Both Mg(2)-Mg(7) bond lengths are 3.17 Å. There are two shorter (3.10 Å) and two longer (3.12 Å) Mg(2)-Mg(4) bond lengths. All Mg(2)-Mg(5) bond lengths are 3.24 Å. In the third Mg site, Mg(3) is bonded to two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), two equivalent Cu(1), and two equivalent Al(1) atoms to form distorted MgMg8Al2Cu2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra, corners with four equivalent Mg(2)Mg12 cuboctahedra, corners with four equivalent Mg(4)Mg12 cuboctahedra, corners with six equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, edges with two equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, edges with two equivalent Cu(1)Mg10Al2 cuboctahedra, edges with two equivalent Al(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, faces with two equivalent Cu(1)Mg10Al2 cuboctahedra, and faces with two equivalent Al(1)Mg10Cu2 cuboctahedra. Both Mg(3)-Mg(3) bond lengths are 3.12 Å. Both Mg(3)-Mg(5) bond lengths are 3.03 Å. Both Mg(3)-Mg(6) bond lengths are 3.09 Å. Both Mg(3)-Mg(7) bond lengths are 3.05 Å. There is one shorter (3.06 Å) and one longer (3.16 Å) Mg(3)-Cu(1) bond length. There is one shorter (3.05 Å) and one longer (3.17 Å) Mg(3)-Al(1) bond length. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), and two equivalent Mg(7) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, corners with four equivalent Cu(1)Mg10Al2 cuboctahedra, corners with four equivalent Al(1)Mg10Cu2 cuboctahedra, corners with six equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with two equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, and faces with two equivalent Mg(3)Mg8Al2Cu2 cuboctahedra. There is one shorter (3.11 Å) and one longer (3.12 Å) Mg(4)-Mg(4) bond length. Both Mg(4)-Mg(5) bond lengths are 3.28 Å. Both Mg(4)-Mg(6) bond lengths are 3.16 Å. Both Mg(4)-Mg(7) bond lengths are 3.21 Å. In the fifth Mg site, Mg(5) is bonded in a 2-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(6), two equivalent Mg(7), one Cu(1), and one Al(1) atom. There is one shorter (3.06 Å) and one longer (3.17 Å) Mg(5)-Mg(6) bond length. There is one shorter (3.04 Å) and one longer (3.19 Å) Mg(5)-Mg(7) bond length. The Mg(5)-Cu(1) bond length is 2.98 Å. The Mg(5)-Al(1) bond length is 2.99 Å. In the sixth Mg site, Mg(6) is bonded to one Mg(1), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(7), four equivalent Mg(5), and one Al(1) atom to form distorted MgMg11Al cuboctahedra that share corners with six equivalent Mg(6)Mg11Al cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with two equivalent Al(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra,  a faceface with one Mg(1)Mg12 cuboctahedra,  a faceface with one Al(1)Mg10Cu2 cuboctahedra, faces with two equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, faces with three equivalent Mg(2)Mg12 cuboctahedra, and faces with three equivalent Cu(1)Mg10Al2 cuboctahedra. Both Mg(6)-Mg(7) bond lengths are 3.12 Å. The Mg(6)-Al(1) bond length is 3.06 Å. In the seventh Mg site, Mg(7) is bonded in a distorted single-bond geometry to one Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(6), four equivalent Mg(5), and one Cu(1) atom. The Mg(7)-Cu(1) bond length is 3.01 Å. Cu(1) is bonded to two equivalent Mg(7), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Al(1) atoms to form CuMg10Al2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra, corners with six equivalent Cu(1)Mg10Al2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Al(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Al(1)Mg10Cu2 cuboctahedra, faces with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, and faces with six equivalent Mg(6)Mg11Al cuboctahedra. Both Cu(1)-Al(1) bond lengths are 3.12 Å. Al(1) is bonded to two equivalent Mg(6), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Cu(1) atoms to form AlMg10Cu2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Al(1)Mg10Cu2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Cu(1)Mg10Al2 cuboctahedra, edges with four equivalent Mg(6)Mg11Al cuboctahedra, edges with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra, faces with two equivalent Mg(6)Mg11Al cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Cu(1)Mg10Al2 cuboctahedra, and faces with four equivalent Mg(3)Mg8Al2Cu2 cuboctahedra.