Hf2CuAl3 crystallizes in the trigonal R-3m space group. Hf(1) is bonded in a 16-coordinate geometry to four equivalent Hf(1), three equivalent Cu(1), and nine equivalent Al(1) atoms. Cu(1) is bonded to six equivalent Hf(1) and six equivalent Al(1) atoms to form CuHf6Al6 cuboctahedra that share corners with six equivalent Cu(1)Hf6Al6 cuboctahedra, corners with twelve equivalent Al(1)Hf6Al4Cu2 cuboctahedra, edges with six equivalent Cu(1)Hf6Al6 cuboctahedra, and faces with eighteen equivalent Al(1)Hf6Al4Cu2 cuboctahedra. Al(1) is bonded to six equivalent Hf(1), two equivalent Cu(1), and four equivalent Al(1) atoms to form distorted AlHf6Al4Cu2 cuboctahedra that share corners with four equivalent Cu(1)Hf6Al6 cuboctahedra, corners with fourteen equivalent Al(1)Hf6Al4Cu2 cuboctahedra, edges with six equivalent Al(1)Hf6Al4Cu2 cuboctahedra, faces with six equivalent Cu(1)Hf6Al6 cuboctahedra, and faces with twelve equivalent Al(1)Hf6Al4Cu2 cuboctahedra.
Hf2CuAl3 crystallizes in the trigonal R-3m space group. Hf(1) is bonded in a 16-coordinate geometry to four equivalent Hf(1), three equivalent Cu(1), and nine equivalent Al(1) atoms. There is one shorter (3.10 Å) and three longer (3.19 Å) Hf(1)-Hf(1) bond lengths. All Hf(1)-Cu(1) bond lengths are 3.07 Å. There are three shorter (2.99 Å) and six longer (3.04 Å) Hf(1)-Al(1) bond lengths. Cu(1) is bonded to six equivalent Hf(1) and six equivalent Al(1) atoms to form CuHf6Al6 cuboctahedra that share corners with six equivalent Cu(1)Hf6Al6 cuboctahedra, corners with twelve equivalent Al(1)Hf6Al4Cu2 cuboctahedra, edges with six equivalent Cu(1)Hf6Al6 cuboctahedra, and faces with eighteen equivalent Al(1)Hf6Al4Cu2 cuboctahedra. All Cu(1)-Al(1) bond lengths are 2.56 Å. Al(1) is bonded to six equivalent Hf(1), two equivalent Cu(1), and four equivalent Al(1) atoms to form distorted AlHf6Al4Cu2 cuboctahedra that share corners with four equivalent Cu(1)Hf6Al6 cuboctahedra, corners with fourteen equivalent Al(1)Hf6Al4Cu2 cuboctahedra, edges with six equivalent Al(1)Hf6Al4Cu2 cuboctahedra, faces with six equivalent Cu(1)Hf6Al6 cuboctahedra, and faces with twelve equivalent Al(1)Hf6Al4Cu2 cuboctahedra. All Al(1)-Al(1) bond lengths are 2.62 Å.