Hf4FeS8 crystallizes in the monoclinic C2/m space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one S(1), one S(2), and four equivalent S(3) atoms to form HfS6 octahedra that share corners with two equivalent Fe(1)S6 octahedra, edges with two equivalent Hf(1)S6 octahedra, edges with four equivalent Hf(2)S6 octahedra, and  a faceface with one Fe(1)S6 octahedra. The corner-sharing octahedral tilt angles are 48°. In the second Hf site, Hf(2) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form HfS6 octahedra that share corners with four equivalent Fe(1)S6 octahedra, edges with two equivalent Hf(2)S6 octahedra, and edges with four equivalent Hf(1)S6 octahedra. The corner-sharing octahedral tilt angles are 48°. Fe(1) is bonded to two equivalent S(1) and four equivalent S(3) atoms to form FeS6 octahedra that share corners with four equivalent Hf(1)S6 octahedra, corners with eight equivalent Hf(2)S6 octahedra, and faces with two equivalent Hf(1)S6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are three inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Hf(1), two equivalent Hf(2), and one Fe(1) atom. In the second S site, S(2) is bonded in a distorted T-shaped geometry to one Hf(1) and two equivalent Hf(2) atoms. In the third S site, S(3) is bonded in a rectangular see-saw-like geometry to one Hf(2), two equivalent Hf(1), and one Fe(1) atom.
Hf4FeS8 crystallizes in the monoclinic C2/m space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one S(1), one S(2), and four equivalent S(3) atoms to form HfS6 octahedra that share corners with two equivalent Fe(1)S6 octahedra, edges with two equivalent Hf(1)S6 octahedra, edges with four equivalent Hf(2)S6 octahedra, and  a faceface with one Fe(1)S6 octahedra. The corner-sharing octahedral tilt angles are 48°. The Hf(1)-S(1) bond length is 2.56 Å. The Hf(1)-S(2) bond length is 2.53 Å. There are two shorter (2.56 Å) and two longer (2.57 Å) Hf(1)-S(3) bond lengths. In the second Hf site, Hf(2) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form HfS6 octahedra that share corners with four equivalent Fe(1)S6 octahedra, edges with two equivalent Hf(2)S6 octahedra, and edges with four equivalent Hf(1)S6 octahedra. The corner-sharing octahedral tilt angles are 48°. Both Hf(2)-S(1) bond lengths are 2.58 Å. Both Hf(2)-S(2) bond lengths are 2.53 Å. Both Hf(2)-S(3) bond lengths are 2.57 Å. Fe(1) is bonded to two equivalent S(1) and four equivalent S(3) atoms to form FeS6 octahedra that share corners with four equivalent Hf(1)S6 octahedra, corners with eight equivalent Hf(2)S6 octahedra, and faces with two equivalent Hf(1)S6 octahedra. The corner-sharing octahedral tilt angles are 48°. Both Fe(1)-S(1) bond lengths are 2.51 Å. All Fe(1)-S(3) bond lengths are 2.49 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Hf(1), two equivalent Hf(2), and one Fe(1) atom. In the second S site, S(2) is bonded in a distorted T-shaped geometry to one Hf(1) and two equivalent Hf(2) atoms. In the third S site, S(3) is bonded in a rectangular see-saw-like geometry to one Hf(2), two equivalent Hf(1), and one Fe(1) atom.