UCu4Al8 crystallizes in the tetragonal I4/mmm space group. U(1) is bonded in a 20-coordinate geometry to eight equivalent Cu(1), four equivalent Al(1), and eight equivalent Al(2) atoms. Cu(1) is bonded in a 12-coordinate geometry to two equivalent U(1), two equivalent Cu(1), four equivalent Al(1), and four equivalent Al(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 10-coordinate geometry to one U(1), four equivalent Cu(1), one Al(1), and four equivalent Al(2) atoms. In the second Al site, Al(2) is bonded in a 4-coordinate geometry to two equivalent U(1), four equivalent Cu(1), and four equivalent Al(1) atoms.
UCu4Al8 crystallizes in the tetragonal I4/mmm space group. U(1) is bonded in a 20-coordinate geometry to eight equivalent Cu(1), four equivalent Al(1), and eight equivalent Al(2) atoms. All U(1)-Cu(1) bond lengths are 3.34 Å. All U(1)-Al(1) bond lengths are 3.04 Å. All U(1)-Al(2) bond lengths are 3.20 Å. Cu(1) is bonded in a 12-coordinate geometry to two equivalent U(1), two equivalent Cu(1), four equivalent Al(1), and four equivalent Al(2) atoms. Both Cu(1)-Cu(1) bond lengths are 2.56 Å. All Cu(1)-Al(1) bond lengths are 2.67 Å. All Cu(1)-Al(2) bond lengths are 2.55 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 10-coordinate geometry to one U(1), four equivalent Cu(1), one Al(1), and four equivalent Al(2) atoms. The Al(1)-Al(1) bond length is 2.67 Å. There are two shorter (2.79 Å) and two longer (2.80 Å) Al(1)-Al(2) bond lengths. In the second Al site, Al(2) is bonded in a 4-coordinate geometry to two equivalent U(1), four equivalent Cu(1), and four equivalent Al(1) atoms.