Ho3NSe3 crystallizes in the monoclinic C2/c space group. There are three inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 6-coordinate geometry to one N(1), one Se(1), two equivalent Se(2), and two equivalent Se(3) atoms. In the second Ho site, Ho(2) is bonded to one N(1), one Se(2), two equivalent Se(1), and two equivalent Se(3) atoms to form distorted HoSe5N octahedra that share  a cornercorner with one Ho(3)Se4N2 octahedra, edges with two equivalent Ho(2)Se5N octahedra, and edges with four equivalent Ho(3)Se4N2 octahedra. The corner-sharing octahedral tilt angles are 10°. In the third Ho site, Ho(3) is bonded to two equivalent N(1), one Se(2), one Se(3), and two equivalent Se(1) atoms to form distorted HoSe4N2 octahedra that share  a cornercorner with one Ho(2)Se5N octahedra, edges with two equivalent Ho(3)Se4N2 octahedra, and edges with four equivalent Ho(2)Se5N octahedra. The corner-sharing octahedral tilt angles are 10°. N(1) is bonded to one Ho(1), one Ho(2), and two equivalent Ho(3) atoms to form NHo4 tetrahedra that share corners with three equivalent Se(1)Ho5 square pyramids, corners with four equivalent Se(3)Ho5 square pyramids,  an edgeedge with one Se(3)Ho5 square pyramid, edges with two equivalent Se(1)Ho5 square pyramids, and  an edgeedge with one N(1)Ho4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one Ho(1), two equivalent Ho(2), and two equivalent Ho(3) atoms to form SeHo5 square pyramids that share corners with two equivalent Se(3)Ho5 square pyramids, corners with three equivalent N(1)Ho4 tetrahedra, edges with two equivalent Se(1)Ho5 square pyramids, edges with three equivalent Se(3)Ho5 square pyramids, and edges with two equivalent N(1)Ho4 tetrahedra. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Ho(2), one Ho(3), and two equivalent Ho(1) atoms. In the third Se site, Se(3) is bonded to one Ho(3), two equivalent Ho(1), and two equivalent Ho(2) atoms to form SeHo5 square pyramids that share corners with two equivalent Se(1)Ho5 square pyramids, corners with four equivalent N(1)Ho4 tetrahedra, edges with two equivalent Se(3)Ho5 square pyramids, edges with three equivalent Se(1)Ho5 square pyramids, and  an edgeedge with one N(1)Ho4 tetrahedra.
Ho3NSe3 crystallizes in the monoclinic C2/c space group. There are three inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 6-coordinate geometry to one N(1), one Se(1), two equivalent Se(2), and two equivalent Se(3) atoms. The Ho(1)-N(1) bond length is 2.22 Å. The Ho(1)-Se(1) bond length is 3.02 Å. There is one shorter (2.84 Å) and one longer (2.89 Å) Ho(1)-Se(2) bond length. There is one shorter (2.89 Å) and one longer (2.99 Å) Ho(1)-Se(3) bond length. In the second Ho site, Ho(2) is bonded to one N(1), one Se(2), two equivalent Se(1), and two equivalent Se(3) atoms to form distorted HoSe5N octahedra that share  a cornercorner with one Ho(3)Se4N2 octahedra, edges with two equivalent Ho(2)Se5N octahedra, and edges with four equivalent Ho(3)Se4N2 octahedra. The corner-sharing octahedral tilt angles are 10°. The Ho(2)-N(1) bond length is 2.23 Å. The Ho(2)-Se(2) bond length is 2.80 Å. There is one shorter (2.86 Å) and one longer (2.92 Å) Ho(2)-Se(1) bond length. There is one shorter (2.87 Å) and one longer (2.89 Å) Ho(2)-Se(3) bond length. In the third Ho site, Ho(3) is bonded to two equivalent N(1), one Se(2), one Se(3), and two equivalent Se(1) atoms to form distorted HoSe4N2 octahedra that share  a cornercorner with one Ho(2)Se5N octahedra, edges with two equivalent Ho(3)Se4N2 octahedra, and edges with four equivalent Ho(2)Se5N octahedra. The corner-sharing octahedral tilt angles are 10°. Both Ho(3)-N(1) bond lengths are 2.25 Å. The Ho(3)-Se(2) bond length is 2.98 Å. The Ho(3)-Se(3) bond length is 2.95 Å. There is one shorter (2.87 Å) and one longer (2.95 Å) Ho(3)-Se(1) bond length. N(1) is bonded to one Ho(1), one Ho(2), and two equivalent Ho(3) atoms to form NHo4 tetrahedra that share corners with three equivalent Se(1)Ho5 square pyramids, corners with four equivalent Se(3)Ho5 square pyramids,  an edgeedge with one Se(3)Ho5 square pyramid, edges with two equivalent Se(1)Ho5 square pyramids, and  an edgeedge with one N(1)Ho4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one Ho(1), two equivalent Ho(2), and two equivalent Ho(3) atoms to form SeHo5 square pyramids that share corners with two equivalent Se(3)Ho5 square pyramids, corners with three equivalent N(1)Ho4 tetrahedra, edges with two equivalent Se(1)Ho5 square pyramids, edges with three equivalent Se(3)Ho5 square pyramids, and edges with two equivalent N(1)Ho4 tetrahedra. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Ho(2), one Ho(3), and two equivalent Ho(1) atoms. In the third Se site, Se(3) is bonded to one Ho(3), two equivalent Ho(1), and two equivalent Ho(2) atoms to form SeHo5 square pyramids that share corners with two equivalent Se(1)Ho5 square pyramids, corners with four equivalent N(1)Ho4 tetrahedra, edges with two equivalent Se(3)Ho5 square pyramids, edges with three equivalent Se(1)Ho5 square pyramids, and  an edgeedge with one N(1)Ho4 tetrahedra.