CuAl3 crystallizes in the tetragonal P4/mmm space group. Cu(1) is bonded in a distorted body-centered cubic geometry to eight equivalent Al(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to four equivalent Al(1) and eight equivalent Al(2) atoms to form AlAl12 cuboctahedra that share corners with four equivalent Al(1)Al12 cuboctahedra, corners with sixteen equivalent Al(2)Al4Cu4 cuboctahedra, edges with eight equivalent Al(2)Al4Cu4 cuboctahedra, and faces with eight equivalent Al(1)Al12 cuboctahedra. In the second Al site, Al(2) is bonded to four equivalent Cu(1) and four equivalent Al(1) atoms to form distorted AlAl4Cu4 cuboctahedra that share corners with eight equivalent Al(1)Al12 cuboctahedra, corners with eight equivalent Al(2)Al4Cu4 cuboctahedra, edges with four equivalent Al(1)Al12 cuboctahedra, edges with twelve equivalent Al(2)Al4Cu4 cuboctahedra, and faces with six equivalent Al(2)Al4Cu4 cuboctahedra.
CuAl3 crystallizes in the tetragonal P4/mmm space group. Cu(1) is bonded in a distorted body-centered cubic geometry to eight equivalent Al(2) atoms. All Cu(1)-Al(2) bond lengths are 2.60 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to four equivalent Al(1) and eight equivalent Al(2) atoms to form AlAl12 cuboctahedra that share corners with four equivalent Al(1)Al12 cuboctahedra, corners with sixteen equivalent Al(2)Al4Cu4 cuboctahedra, edges with eight equivalent Al(2)Al4Cu4 cuboctahedra, and faces with eight equivalent Al(1)Al12 cuboctahedra. All Al(1)-Al(1) bond lengths are 2.78 Å. All Al(1)-Al(2) bond lengths are 2.85 Å. In the second Al site, Al(2) is bonded to four equivalent Cu(1) and four equivalent Al(1) atoms to form distorted AlAl4Cu4 cuboctahedra that share corners with eight equivalent Al(1)Al12 cuboctahedra, corners with eight equivalent Al(2)Al4Cu4 cuboctahedra, edges with four equivalent Al(1)Al12 cuboctahedra, edges with twelve equivalent Al(2)Al4Cu4 cuboctahedra, and faces with six equivalent Al(2)Al4Cu4 cuboctahedra.