Hf5CuSb3 crystallizes in the hexagonal P6_3/mcm space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 6-coordinate geometry to six equivalent Sb(1) atoms. In the second Hf site, Hf(2) is bonded to two equivalent Cu(1) and five equivalent Sb(1) atoms to form a mixture of distorted corner, edge, and face-sharing HfCu2Sb5 pentagonal bipyramids. Cu(1) is bonded to six equivalent Hf(2) atoms to form face-sharing CuHf6 octahedra. Sb(1) is bonded in a 9-coordinate geometry to four equivalent Hf(1) and five equivalent Hf(2) atoms.
Hf5CuSb3 crystallizes in the hexagonal P6_3/mcm space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 6-coordinate geometry to six equivalent Sb(1) atoms. All Hf(1)-Sb(1) bond lengths are 3.00 Å. In the second Hf site, Hf(2) is bonded to two equivalent Cu(1) and five equivalent Sb(1) atoms to form a mixture of distorted corner, edge, and face-sharing HfCu2Sb5 pentagonal bipyramids. Both Hf(2)-Cu(1) bond lengths are 2.65 Å. There are a spread of Hf(2)-Sb(1) bond distances ranging from 2.91-3.05 Å. Cu(1) is bonded to six equivalent Hf(2) atoms to form face-sharing CuHf6 octahedra. Sb(1) is bonded in a 9-coordinate geometry to four equivalent Hf(1) and five equivalent Hf(2) atoms.