U3LaAl8 crystallizes in the trigonal R3m space group. There are three inequivalent U sites. In the first U site, U(1) is bonded in a 16-coordinate geometry to one U(3), three equivalent U(2), three equivalent Al(1), three equivalent Al(4), and six equivalent Al(2) atoms. In the second U site, U(2) is bonded in a 13-coordinate geometry to three equivalent U(1), one La(1), three equivalent Al(2), three equivalent Al(4), and six equivalent Al(1) atoms. In the third U site, U(3) is bonded in a 16-coordinate geometry to one U(1), three equivalent La(1), three equivalent Al(1), three equivalent Al(3), and six equivalent Al(2) atoms. La(1) is bonded in a 16-coordinate geometry to one U(2), three equivalent U(3), three equivalent Al(2), three equivalent Al(3), and six equivalent Al(1) atoms. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one U(1), one U(3), two equivalent U(2), two equivalent La(1), one Al(3), one Al(4), and four equivalent Al(1) atoms to form distorted AlLa2U4Al6 cuboctahedra that share corners with two equivalent Al(3)La3U3Al6 cuboctahedra, corners with two equivalent Al(4)U6Al6 cuboctahedra, corners with four equivalent Al(1)La2U4Al6 cuboctahedra, corners with ten equivalent Al(2)LaU5Al6 cuboctahedra, edges with two equivalent Al(1)La2U4Al6 cuboctahedra, edges with four equivalent Al(2)LaU5Al6 cuboctahedra, faces with three equivalent Al(3)La3U3Al6 cuboctahedra, faces with three equivalent Al(4)U6Al6 cuboctahedra, faces with four equivalent Al(2)LaU5Al6 cuboctahedra, and faces with eight equivalent Al(1)La2U4Al6 cuboctahedra. In the second Al site, Al(2) is bonded to one U(2), two equivalent U(1), two equivalent U(3), one La(1), one Al(3), one Al(4), and four equivalent Al(2) atoms to form AlLaU5Al6 cuboctahedra that share corners with two equivalent Al(3)La3U3Al6 cuboctahedra, corners with two equivalent Al(4)U6Al6 cuboctahedra, corners with four equivalent Al(2)LaU5Al6 cuboctahedra, corners with ten equivalent Al(1)La2U4Al6 cuboctahedra, edges with two equivalent Al(2)LaU5Al6 cuboctahedra, edges with four equivalent Al(1)La2U4Al6 cuboctahedra, faces with three equivalent Al(3)La3U3Al6 cuboctahedra, faces with three equivalent Al(4)U6Al6 cuboctahedra, faces with four equivalent Al(1)La2U4Al6 cuboctahedra, and faces with eight equivalent Al(2)LaU5Al6 cuboctahedra. In the third Al site, Al(3) is bonded to three equivalent U(3), three equivalent La(1), three equivalent Al(1), and three equivalent Al(2) atoms to form AlLa3U3Al6 cuboctahedra that share corners with six equivalent Al(1)La2U4Al6 cuboctahedra, corners with six equivalent Al(2)LaU5Al6 cuboctahedra, corners with six equivalent Al(4)U6Al6 cuboctahedra, edges with six equivalent Al(3)La3U3Al6 cuboctahedra, faces with nine equivalent Al(1)La2U4Al6 cuboctahedra, and faces with nine equivalent Al(2)LaU5Al6 cuboctahedra. In the fourth Al site, Al(4) is bonded to three equivalent U(1), three equivalent U(2), three equivalent Al(1), and three equivalent Al(2) atoms to form AlU6Al6 cuboctahedra that share corners with six equivalent Al(1)La2U4Al6 cuboctahedra, corners with six equivalent Al(3)La3U3Al6 cuboctahedra, corners with six equivalent Al(2)LaU5Al6 cuboctahedra, edges with six equivalent Al(4)U6Al6 cuboctahedra, faces with nine equivalent Al(1)La2U4Al6 cuboctahedra, and faces with nine equivalent Al(2)LaU5Al6 cuboctahedra.
U3LaAl8 crystallizes in the trigonal R3m space group. There are three inequivalent U sites. In the first U site, U(1) is bonded in a 16-coordinate geometry to one U(3), three equivalent U(2), three equivalent Al(1), three equivalent Al(4), and six equivalent Al(2) atoms. The U(1)-U(3) bond length is 2.51 Å. All U(1)-U(2) bond lengths are 3.51 Å. All U(1)-Al(1) bond lengths are 3.43 Å. All U(1)-Al(4) bond lengths are 3.33 Å. All U(1)-Al(2) bond lengths are 3.06 Å. In the second U site, U(2) is bonded in a 13-coordinate geometry to three equivalent U(1), one La(1), three equivalent Al(2), three equivalent Al(4), and six equivalent Al(1) atoms. The U(2)-La(1) bond length is 3.28 Å. All U(2)-Al(2) bond lengths are 3.14 Å. All U(2)-Al(4) bond lengths are 3.25 Å. All U(2)-Al(1) bond lengths are 3.21 Å. In the third U site, U(3) is bonded in a 16-coordinate geometry to one U(1), three equivalent La(1), three equivalent Al(1), three equivalent Al(3), and six equivalent Al(2) atoms. All U(3)-La(1) bond lengths are 3.60 Å. All U(3)-Al(1) bond lengths are 3.67 Å. All U(3)-Al(3) bond lengths are 3.36 Å. All U(3)-Al(2) bond lengths are 3.04 Å. La(1) is bonded in a 16-coordinate geometry to one U(2), three equivalent U(3), three equivalent Al(2), three equivalent Al(3), and six equivalent Al(1) atoms. All La(1)-Al(2) bond lengths are 3.29 Å. All La(1)-Al(3) bond lengths are 3.27 Å. All La(1)-Al(1) bond lengths are 3.24 Å. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one U(1), one U(3), two equivalent U(2), two equivalent La(1), one Al(3), one Al(4), and four equivalent Al(1) atoms to form distorted AlLa2U4Al6 cuboctahedra that share corners with two equivalent Al(3)La3U3Al6 cuboctahedra, corners with two equivalent Al(4)U6Al6 cuboctahedra, corners with four equivalent Al(1)La2U4Al6 cuboctahedra, corners with ten equivalent Al(2)LaU5Al6 cuboctahedra, edges with two equivalent Al(1)La2U4Al6 cuboctahedra, edges with four equivalent Al(2)LaU5Al6 cuboctahedra, faces with three equivalent Al(3)La3U3Al6 cuboctahedra, faces with three equivalent Al(4)U6Al6 cuboctahedra, faces with four equivalent Al(2)LaU5Al6 cuboctahedra, and faces with eight equivalent Al(1)La2U4Al6 cuboctahedra. The Al(1)-Al(3) bond length is 2.80 Å. The Al(1)-Al(4) bond length is 2.69 Å. There are two shorter (2.76 Å) and two longer (2.79 Å) Al(1)-Al(1) bond lengths. In the second Al site, Al(2) is bonded to one U(2), two equivalent U(1), two equivalent U(3), one La(1), one Al(3), one Al(4), and four equivalent Al(2) atoms to form AlLaU5Al6 cuboctahedra that share corners with two equivalent Al(3)La3U3Al6 cuboctahedra, corners with two equivalent Al(4)U6Al6 cuboctahedra, corners with four equivalent Al(2)LaU5Al6 cuboctahedra, corners with ten equivalent Al(1)La2U4Al6 cuboctahedra, edges with two equivalent Al(2)LaU5Al6 cuboctahedra, edges with four equivalent Al(1)La2U4Al6 cuboctahedra, faces with three equivalent Al(3)La3U3Al6 cuboctahedra, faces with three equivalent Al(4)U6Al6 cuboctahedra, faces with four equivalent Al(1)La2U4Al6 cuboctahedra, and faces with eight equivalent Al(2)LaU5Al6 cuboctahedra. The Al(2)-Al(3) bond length is 2.74 Å. The Al(2)-Al(4) bond length is 2.69 Å. There are two shorter (2.76 Å) and two longer (2.79 Å) Al(2)-Al(2) bond lengths. In the third Al site, Al(3) is bonded to three equivalent U(3), three equivalent La(1), three equivalent Al(1), and three equivalent Al(2) atoms to form AlLa3U3Al6 cuboctahedra that share corners with six equivalent Al(1)La2U4Al6 cuboctahedra, corners with six equivalent Al(2)LaU5Al6 cuboctahedra, corners with six equivalent Al(4)U6Al6 cuboctahedra, edges with six equivalent Al(3)La3U3Al6 cuboctahedra, faces with nine equivalent Al(1)La2U4Al6 cuboctahedra, and faces with nine equivalent Al(2)LaU5Al6 cuboctahedra. In the fourth Al site, Al(4) is bonded to three equivalent U(1), three equivalent U(2), three equivalent Al(1), and three equivalent Al(2) atoms to form AlU6Al6 cuboctahedra that share corners with six equivalent Al(1)La2U4Al6 cuboctahedra, corners with six equivalent Al(3)La3U3Al6 cuboctahedra, corners with six equivalent Al(2)LaU5Al6 cuboctahedra, edges with six equivalent Al(4)U6Al6 cuboctahedra, faces with nine equivalent Al(1)La2U4Al6 cuboctahedra, and faces with nine equivalent Al(2)LaU5Al6 cuboctahedra.