The structure described by Hf2ON2 is Ilmenite-like structured and crystallizes in the monoclinic P2/c space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one N(1), one N(2), one N(3), and three equivalent O(1) atoms to form distorted HfN3O3 octahedra that share corners with three equivalent Hf(1)N3O3 octahedra, corners with six equivalent Hf(2)N5O octahedra,  an edgeedge with one Hf(1)N3O3 octahedra, edges with two equivalent Hf(2)N5O octahedra, and  a faceface with one Hf(1)N3O3 octahedra. The corner-sharing octahedral tilt angles range from 47-63°. In the second Hf site, Hf(2) is bonded to one N(2), one N(3), three equivalent N(1), and one O(1) atom to form distorted HfN5O octahedra that share corners with three equivalent Hf(2)N5O octahedra, corners with six equivalent Hf(1)N3O3 octahedra,  an edgeedge with one Hf(2)N5O octahedra, edges with two equivalent Hf(1)N3O3 octahedra, and  a faceface with one Hf(2)N5O octahedra. The corner-sharing octahedral tilt angles range from 47-63°. There are three inequivalent N sites. In the first N site, N(1) is bonded to one Hf(1) and three equivalent Hf(2) atoms to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, corners with four equivalent N(2)Hf4 trigonal pyramids, corners with four equivalent O(1)Hf4 trigonal pyramids,  an edgeedge with one N(3)Hf4 trigonal pyramid,  an edgeedge with one O(1)Hf4 trigonal pyramid, and edges with two equivalent N(1)Hf4 trigonal pyramids. In the second N site, N(2) is bonded to two equivalent Hf(1) and two equivalent Hf(2) atoms to form distorted NHf4 trigonal pyramids that share corners with four equivalent O(1)Hf4 trigonal pyramids, corners with eight equivalent N(1)Hf4 trigonal pyramids, edges with two equivalent N(3)Hf4 trigonal pyramids, and edges with two equivalent O(1)Hf4 trigonal pyramids. In the third N site, N(3) is bonded to two equivalent Hf(1) and two equivalent Hf(2) atoms to form distorted NHf4 trigonal pyramids that share corners with four equivalent N(1)Hf4 trigonal pyramids, corners with eight equivalent O(1)Hf4 trigonal pyramids, edges with two equivalent N(1)Hf4 trigonal pyramids, and edges with two equivalent N(2)Hf4 trigonal pyramids. O(1) is bonded to one Hf(2) and three equivalent Hf(1) atoms to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent O(1)Hf4 trigonal pyramids, corners with four equivalent N(1)Hf4 trigonal pyramids, corners with four equivalent N(3)Hf4 trigonal pyramids,  an edgeedge with one N(1)Hf4 trigonal pyramid,  an edgeedge with one N(2)Hf4 trigonal pyramid, and edges with two equivalent O(1)Hf4 trigonal pyramids. is represented by the CIF file [CIF]
data_Hf2N2O
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.490
_cell_length_b   5.815
_cell_length_c   7.931
_cell_angle_alpha   85.301
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   252.336
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Hf  Hf0  1  1.000  0.279  0.143  1.0
  Hf  Hf1  1  0.000  0.279  0.643  1.0
  Hf  Hf2  1  0.488  0.211  0.354  1.0
  Hf  Hf3  1  0.512  0.211  0.854  1.0
  Hf  Hf4  1  0.488  0.789  0.146  1.0
  Hf  Hf5  1  0.512  0.789  0.646  1.0
  Hf  Hf6  1  1.000  0.721  0.357  1.0
  Hf  Hf7  1  0.000  0.721  0.857  1.0
  N  N8  1  0.652  0.152  0.100  1.0
  N  N9  1  0.348  0.152  0.600  1.0
  N  N10  1  0.284  0.500  0.250  1.0
  N  N11  1  0.716  0.500  0.750  1.0
  N  N12  1  0.652  0.848  0.400  1.0
  N  N13  1  0.348  0.848  0.900  1.0
  N  N14  1  0.192  0.000  0.250  1.0
  N  N15  1  0.808  0.000  0.750  1.0
  O  O16  1  0.847  0.351  0.399  1.0
  O  O17  1  0.153  0.351  0.899  1.0
  O  O18  1  0.847  0.649  0.101  1.0
  O  O19  1  0.153  0.649  0.601  1.0
[/CIF]
.
The structure described by Hf2ON2 is Ilmenite-like structured and crystallizes in the monoclinic P2/c space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one N(1), one N(2), one N(3), and three equivalent O(1) atoms to form distorted HfN3O3 octahedra that share corners with three equivalent Hf(1)N3O3 octahedra, corners with six equivalent Hf(2)N5O octahedra,  an edgeedge with one Hf(1)N3O3 octahedra, edges with two equivalent Hf(2)N5O octahedra, and  a faceface with one Hf(1)N3O3 octahedra. The corner-sharing octahedral tilt angles range from 47-63°. In the second Hf site, Hf(2) is bonded to one N(2), one N(3), three equivalent N(1), and one O(1) atom to form distorted HfN5O octahedra that share corners with three equivalent Hf(2)N5O octahedra, corners with six equivalent Hf(1)N3O3 octahedra,  an edgeedge with one Hf(2)N5O octahedra, edges with two equivalent Hf(1)N3O3 octahedra, and  a faceface with one Hf(2)N5O octahedra. The corner-sharing octahedral tilt angles range from 47-63°. There are three inequivalent N sites. In the first N site, N(1) is bonded to one Hf(1) and three equivalent Hf(2) atoms to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, corners with four equivalent N(2)Hf4 trigonal pyramids, corners with four equivalent O(1)Hf4 trigonal pyramids,  an edgeedge with one N(3)Hf4 trigonal pyramid,  an edgeedge with one O(1)Hf4 trigonal pyramid, and edges with two equivalent N(1)Hf4 trigonal pyramids. In the second N site, N(2) is bonded to two equivalent Hf(1) and two equivalent Hf(2) atoms to form distorted NHf4 trigonal pyramids that share corners with four equivalent O(1)Hf4 trigonal pyramids, corners with eight equivalent N(1)Hf4 trigonal pyramids, edges with two equivalent N(3)Hf4 trigonal pyramids, and edges with two equivalent O(1)Hf4 trigonal pyramids. In the third N site, N(3) is bonded to two equivalent Hf(1) and two equivalent Hf(2) atoms to form distorted NHf4 trigonal pyramids that share corners with four equivalent N(1)Hf4 trigonal pyramids, corners with eight equivalent O(1)Hf4 trigonal pyramids, edges with two equivalent N(1)Hf4 trigonal pyramids, and edges with two equivalent N(2)Hf4 trigonal pyramids. O(1) is bonded to one Hf(2) and three equivalent Hf(1) atoms to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent O(1)Hf4 trigonal pyramids, corners with four equivalent N(1)Hf4 trigonal pyramids, corners with four equivalent N(3)Hf4 trigonal pyramids,  an edgeedge with one N(1)Hf4 trigonal pyramid,  an edgeedge with one N(2)Hf4 trigonal pyramid, and edges with two equivalent O(1)Hf4 trigonal pyramids. is represented by the CIF file [CIF]
data_Hf2N2O
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.490
_cell_length_b   5.815
_cell_length_c   7.931
_cell_angle_alpha   85.301
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   252.336
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Hf  Hf0  1  1.000  0.279  0.143  1.0
  Hf  Hf1  1  0.000  0.279  0.643  1.0
  Hf  Hf2  1  0.488  0.211  0.354  1.0
  Hf  Hf3  1  0.512  0.211  0.854  1.0
  Hf  Hf4  1  0.488  0.789  0.146  1.0
  Hf  Hf5  1  0.512  0.789  0.646  1.0
  Hf  Hf6  1  1.000  0.721  0.357  1.0
  Hf  Hf7  1  0.000  0.721  0.857  1.0
  N  N8  1  0.652  0.152  0.100  1.0
  N  N9  1  0.348  0.152  0.600  1.0
  N  N10  1  0.284  0.500  0.250  1.0
  N  N11  1  0.716  0.500  0.750  1.0
  N  N12  1  0.652  0.848  0.400  1.0
  N  N13  1  0.348  0.848  0.900  1.0
  N  N14  1  0.192  0.000  0.250  1.0
  N  N15  1  0.808  0.000  0.750  1.0
  O  O16  1  0.847  0.351  0.399  1.0
  O  O17  1  0.153  0.351  0.899  1.0
  O  O18  1  0.847  0.649  0.101  1.0
  O  O19  1  0.153  0.649  0.601  1.0
[/CIF]
.