ThCr4Al8 crystallizes in the tetragonal I4/mmm space group. Th(1) is bonded in a 20-coordinate geometry to eight equivalent Cr(1), four equivalent Al(2), and eight equivalent Al(1) atoms. Cr(1) is bonded to two equivalent Th(1), two equivalent Cr(1), four equivalent Al(1), and four equivalent Al(2) atoms to form distorted CrTh2Al8Cr2 cuboctahedra that share corners with eight equivalent Al(1)Th2Al6Cr4 cuboctahedra, corners with ten equivalent Cr(1)Th2Al8Cr2 cuboctahedra, edges with four equivalent Cr(1)Th2Al8Cr2 cuboctahedra, edges with four equivalent Al(1)Th2Al6Cr4 cuboctahedra, faces with six equivalent Cr(1)Th2Al8Cr2 cuboctahedra, and faces with eight equivalent Al(1)Th2Al6Cr4 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent Th(1), four equivalent Cr(1), two equivalent Al(1), and four equivalent Al(2) atoms to form distorted AlTh2Al6Cr4 cuboctahedra that share corners with eight equivalent Cr(1)Th2Al8Cr2 cuboctahedra, corners with ten equivalent Al(1)Th2Al6Cr4 cuboctahedra, edges with three equivalent Al(1)Th2Al6Cr4 cuboctahedra, edges with four equivalent Cr(1)Th2Al8Cr2 cuboctahedra, faces with seven equivalent Al(1)Th2Al6Cr4 cuboctahedra, and faces with eight equivalent Cr(1)Th2Al8Cr2 cuboctahedra. In the second Al site, Al(2) is bonded in a 10-coordinate geometry to one Th(1), four equivalent Cr(1), one Al(2), and four equivalent Al(1) atoms.
ThCr4Al8 crystallizes in the tetragonal I4/mmm space group. Th(1) is bonded in a 20-coordinate geometry to eight equivalent Cr(1), four equivalent Al(2), and eight equivalent Al(1) atoms. All Th(1)-Cr(1) bond lengths are 3.43 Å. All Th(1)-Al(2) bond lengths are 3.11 Å. All Th(1)-Al(1) bond lengths are 3.22 Å. Cr(1) is bonded to two equivalent Th(1), two equivalent Cr(1), four equivalent Al(1), and four equivalent Al(2) atoms to form distorted CrTh2Al8Cr2 cuboctahedra that share corners with eight equivalent Al(1)Th2Al6Cr4 cuboctahedra, corners with ten equivalent Cr(1)Th2Al8Cr2 cuboctahedra, edges with four equivalent Cr(1)Th2Al8Cr2 cuboctahedra, edges with four equivalent Al(1)Th2Al6Cr4 cuboctahedra, faces with six equivalent Cr(1)Th2Al8Cr2 cuboctahedra, and faces with eight equivalent Al(1)Th2Al6Cr4 cuboctahedra. Both Cr(1)-Cr(1) bond lengths are 2.51 Å. All Cr(1)-Al(1) bond lengths are 2.59 Å. All Cr(1)-Al(2) bond lengths are 2.72 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent Th(1), four equivalent Cr(1), two equivalent Al(1), and four equivalent Al(2) atoms to form distorted AlTh2Al6Cr4 cuboctahedra that share corners with eight equivalent Cr(1)Th2Al8Cr2 cuboctahedra, corners with ten equivalent Al(1)Th2Al6Cr4 cuboctahedra, edges with three equivalent Al(1)Th2Al6Cr4 cuboctahedra, edges with four equivalent Cr(1)Th2Al8Cr2 cuboctahedra, faces with seven equivalent Al(1)Th2Al6Cr4 cuboctahedra, and faces with eight equivalent Cr(1)Th2Al8Cr2 cuboctahedra. Both Al(1)-Al(1) bond lengths are 2.86 Å. There are two shorter (2.74 Å) and two longer (2.86 Å) Al(1)-Al(2) bond lengths. In the second Al site, Al(2) is bonded in a 10-coordinate geometry to one Th(1), four equivalent Cr(1), one Al(2), and four equivalent Al(1) atoms. The Al(2)-Al(2) bond length is 2.80 Å.