HfNi2Al5 crystallizes in the tetragonal I4/mmm space group. Hf(1) is bonded to four equivalent Al(2) and eight Al(1,1) atoms to form HfAl12 cuboctahedra that share corners with four equivalent Hf(1)Al12 cuboctahedra, faces with four equivalent Hf(1)Al12 cuboctahedra, and faces with four equivalent Al(2)Hf4Al8 cuboctahedra. Ni(1) is bonded in a body-centered cubic geometry to eight equivalent Al(1) atoms. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a 6-coordinate geometry to two equivalent Hf(1), four equivalent Ni(1), and two equivalent Al(2) atoms. In the second Al site, Al(2) is bonded to four equivalent Hf(1) and eight Al(1,1) atoms to form distorted AlHf4Al8 cuboctahedra that share corners with four equivalent Al(2)Hf4Al8 cuboctahedra, faces with four equivalent Hf(1)Al12 cuboctahedra, and faces with four equivalent Al(2)Hf4Al8 cuboctahedra. In the third Al site, Al(1) is bonded in a 6-coordinate geometry to two equivalent Hf(1), four equivalent Ni(1), and two equivalent Al(2) atoms.
HfNi2Al5 crystallizes in the tetragonal I4/mmm space group. Hf(1) is bonded to four equivalent Al(2) and eight Al(1,1) atoms to form HfAl12 cuboctahedra that share corners with four equivalent Hf(1)Al12 cuboctahedra, faces with four equivalent Hf(1)Al12 cuboctahedra, and faces with four equivalent Al(2)Hf4Al8 cuboctahedra. All Hf(1)-Al(2) bond lengths are 2.81 Å. All Hf(1)-Al(1,1) bond lengths are 2.91 Å. Ni(1) is bonded in a body-centered cubic geometry to eight equivalent Al(1) atoms. There are four shorter (2.40 Å) and four longer (2.57 Å) Ni(1)-Al(1) bond lengths. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a 6-coordinate geometry to two equivalent Hf(1), four equivalent Ni(1), and two equivalent Al(2) atoms. Both Al(1)-Al(2) bond lengths are 2.91 Å. In the second Al site, Al(2) is bonded to four equivalent Hf(1) and eight Al(1,1) atoms to form distorted AlHf4Al8 cuboctahedra that share corners with four equivalent Al(2)Hf4Al8 cuboctahedra, faces with four equivalent Hf(1)Al12 cuboctahedra, and faces with four equivalent Al(2)Hf4Al8 cuboctahedra. All Al(2)-Al(1) bond lengths are 2.91 Å. In the third Al site, Al(1) is bonded in a 6-coordinate geometry to two equivalent Hf(1), four equivalent Ni(1), and two equivalent Al(2) atoms. There are two shorter (2.40 Å) and two longer (2.57 Å) Al(1)-Ni(1) bond lengths.