Ho2Se3 crystallizes in the orthorhombic Fddd space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form a mixture of corner and edge-sharing HoSe6 octahedra. The corner-sharing octahedral tilt angles range from 3-5°. In the second Ho site, Ho(2) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form a mixture of corner and edge-sharing HoSe6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to two equivalent Ho(1) and two equivalent Ho(2) atoms. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to two equivalent Ho(1) and two equivalent Ho(2) atoms.
Ho2Se3 crystallizes in the orthorhombic Fddd space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form a mixture of corner and edge-sharing HoSe6 octahedra. The corner-sharing octahedral tilt angles range from 3-5°. Both Ho(1)-Se(2) bond lengths are 2.86 Å. All Ho(1)-Se(1) bond lengths are 2.84 Å. In the second Ho site, Ho(2) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form a mixture of corner and edge-sharing HoSe6 octahedra. The corner-sharing octahedral tilt angles are 5°. Both Ho(2)-Se(2) bond lengths are 2.84 Å. There are two shorter (2.83 Å) and two longer (2.86 Å) Ho(2)-Se(1) bond lengths. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to two equivalent Ho(1) and two equivalent Ho(2) atoms. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to two equivalent Ho(1) and two equivalent Ho(2) atoms.