U2Cu7Al3 crystallizes in the monoclinic P2/m space group. U(1) is bonded in a 6-coordinate geometry to two equivalent Cu(3), two equivalent Cu(4), two equivalent Cu(5), three equivalent Cu(1), and three equivalent Cu(2) atoms. There are five inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 9-coordinate geometry to three equivalent U(1), one Cu(2), two equivalent Cu(4), two equivalent Al(1), and two equivalent Al(2) atoms. In the second Cu site, Cu(2) is bonded in a 12-coordinate geometry to three equivalent U(1), one Cu(1), two equivalent Cu(2), two equivalent Cu(3), two equivalent Cu(5), and two equivalent Al(1) atoms. In the third Cu site, Cu(3) is bonded to four equivalent U(1), two equivalent Cu(5), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuU4Al2Cu6 cuboctahedra that share corners with two equivalent Cu(3)U4Al2Cu6 cuboctahedra, corners with four equivalent Cu(4)U4Al4Cu4 cuboctahedra, edges with four equivalent Cu(5)U4Al2Cu6 cuboctahedra, faces with two equivalent Cu(3)U4Al2Cu6 cuboctahedra, faces with two equivalent Cu(5)U4Al2Cu6 cuboctahedra, and faces with two equivalent Cu(4)U4Al4Cu4 cuboctahedra. In the fourth Cu site, Cu(4) is bonded to four equivalent U(1), four equivalent Cu(1), two equivalent Al(1), and two equivalent Al(2) atoms to form distorted CuU4Al4Cu4 cuboctahedra that share corners with two equivalent Cu(4)U4Al4Cu4 cuboctahedra, corners with four equivalent Cu(3)U4Al2Cu6 cuboctahedra, corners with four equivalent Al(2)Cu6 cuboctahedra, corners with six equivalent Cu(5)U4Al2Cu6 cuboctahedra, edges with two equivalent Cu(5)U4Al2Cu6 cuboctahedra, edges with two equivalent Al(2)Cu6 cuboctahedra, faces with two equivalent Cu(3)U4Al2Cu6 cuboctahedra, and faces with two equivalent Cu(4)U4Al4Cu4 cuboctahedra. In the fifth Cu site, Cu(5) is bonded to four equivalent U(1), two equivalent Cu(3), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuU4Al2Cu6 cuboctahedra that share corners with two equivalent Cu(5)U4Al2Cu6 cuboctahedra, corners with six equivalent Cu(4)U4Al4Cu4 cuboctahedra, edges with two equivalent Cu(4)U4Al4Cu4 cuboctahedra, edges with four equivalent Cu(3)U4Al2Cu6 cuboctahedra, faces with two equivalent Cu(3)U4Al2Cu6 cuboctahedra, and faces with two equivalent Cu(5)U4Al2Cu6 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 7-coordinate geometry to one Cu(3), one Cu(4), one Cu(5), two equivalent Cu(1), and two equivalent Cu(2) atoms. In the second Al site, Al(2) is bonded to two equivalent Cu(4) and four equivalent Cu(1) atoms to form distorted AlCu6 cuboctahedra that share corners with two equivalent Al(2)Cu6 cuboctahedra, corners with four equivalent Cu(4)U4Al4Cu4 cuboctahedra, edges with two equivalent Cu(4)U4Al4Cu4 cuboctahedra, and edges with two equivalent Al(2)Cu6 cuboctahedra.
U2Cu7Al3 crystallizes in the monoclinic P2/m space group. U(1) is bonded in a 6-coordinate geometry to two equivalent Cu(3), two equivalent Cu(4), two equivalent Cu(5), three equivalent Cu(1), and three equivalent Cu(2) atoms. Both U(1)-Cu(3) bond lengths are 3.26 Å. Both U(1)-Cu(4) bond lengths are 3.31 Å. Both U(1)-Cu(5) bond lengths are 3.29 Å. There is one shorter (2.91 Å) and two longer (2.95 Å) U(1)-Cu(1) bond lengths. There are a spread of U(1)-Cu(2) bond distances ranging from 2.90-2.95 Å. There are five inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 9-coordinate geometry to three equivalent U(1), one Cu(2), two equivalent Cu(4), two equivalent Al(1), and two equivalent Al(2) atoms. The Cu(1)-Cu(2) bond length is 2.96 Å. Both Cu(1)-Cu(4) bond lengths are 2.52 Å. Both Cu(1)-Al(1) bond lengths are 2.57 Å. Both Cu(1)-Al(2) bond lengths are 2.57 Å. In the second Cu site, Cu(2) is bonded in a 12-coordinate geometry to three equivalent U(1), one Cu(1), two equivalent Cu(2), two equivalent Cu(3), two equivalent Cu(5), and two equivalent Al(1) atoms. There is one shorter (2.86 Å) and one longer (2.94 Å) Cu(2)-Cu(2) bond length. Both Cu(2)-Cu(3) bond lengths are 2.54 Å. Both Cu(2)-Cu(5) bond lengths are 2.52 Å. Both Cu(2)-Al(1) bond lengths are 2.53 Å. In the third Cu site, Cu(3) is bonded to four equivalent U(1), two equivalent Cu(5), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuU4Al2Cu6 cuboctahedra that share corners with two equivalent Cu(3)U4Al2Cu6 cuboctahedra, corners with four equivalent Cu(4)U4Al4Cu4 cuboctahedra, edges with four equivalent Cu(5)U4Al2Cu6 cuboctahedra, faces with two equivalent Cu(3)U4Al2Cu6 cuboctahedra, faces with two equivalent Cu(5)U4Al2Cu6 cuboctahedra, and faces with two equivalent Cu(4)U4Al4Cu4 cuboctahedra. Both Cu(3)-Cu(5) bond lengths are 2.54 Å. Both Cu(3)-Al(1) bond lengths are 2.49 Å. In the fourth Cu site, Cu(4) is bonded to four equivalent U(1), four equivalent Cu(1), two equivalent Al(1), and two equivalent Al(2) atoms to form distorted CuU4Al4Cu4 cuboctahedra that share corners with two equivalent Cu(4)U4Al4Cu4 cuboctahedra, corners with four equivalent Cu(3)U4Al2Cu6 cuboctahedra, corners with four equivalent Al(2)Cu6 cuboctahedra, corners with six equivalent Cu(5)U4Al2Cu6 cuboctahedra, edges with two equivalent Cu(5)U4Al2Cu6 cuboctahedra, edges with two equivalent Al(2)Cu6 cuboctahedra, faces with two equivalent Cu(3)U4Al2Cu6 cuboctahedra, and faces with two equivalent Cu(4)U4Al4Cu4 cuboctahedra. Both Cu(4)-Al(1) bond lengths are 2.54 Å. Both Cu(4)-Al(2) bond lengths are 2.54 Å. In the fifth Cu site, Cu(5) is bonded to four equivalent U(1), two equivalent Cu(3), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuU4Al2Cu6 cuboctahedra that share corners with two equivalent Cu(5)U4Al2Cu6 cuboctahedra, corners with six equivalent Cu(4)U4Al4Cu4 cuboctahedra, edges with two equivalent Cu(4)U4Al4Cu4 cuboctahedra, edges with four equivalent Cu(3)U4Al2Cu6 cuboctahedra, faces with two equivalent Cu(3)U4Al2Cu6 cuboctahedra, and faces with two equivalent Cu(5)U4Al2Cu6 cuboctahedra. Both Cu(5)-Al(1) bond lengths are 2.49 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 7-coordinate geometry to one Cu(3), one Cu(4), one Cu(5), two equivalent Cu(1), and two equivalent Cu(2) atoms. In the second Al site, Al(2) is bonded to two equivalent Cu(4) and four equivalent Cu(1) atoms to form distorted AlCu6 cuboctahedra that share corners with two equivalent Al(2)Cu6 cuboctahedra, corners with four equivalent Cu(4)U4Al4Cu4 cuboctahedra, edges with two equivalent Cu(4)U4Al4Cu4 cuboctahedra, and edges with two equivalent Al(2)Cu6 cuboctahedra.