data_NbO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.88
_cell_length_b   6.88
_cell_length_c   6.91
_cell_angle_alpha   106.2
_cell_angle_beta   106.2
_cell_angle_gamma   33.44
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NbO2
_chemical_formula_sum   'Nb4 O8'
_cell_volume   172.51
_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
  Nb  Nb0  1  0.88  0.0  0.67  1.0
  Nb  Nb1  1  0.0  0.0  0.89  1.0
  Nb  Nb2  1  0.17  0.0  0.71  1.0
  Nb  Nb3  1  0.29  0.0  0.94  1.0
  O  O4  1  0.03  0.0  0.42  1.0
  O  O5  1  0.01  0.0  0.61  1.0
  O  O6  1  0.81  0.0  0.02  1.0
  O  O7  1  0.12  0.0  0.29  1.0
  O  O8  1  0.05  0.0  0.32  1.0
  O  O9  1  0.36  0.0  0.59  1.0
  O  O10  1  0.16  0.0  1.0  1.0
  O  O11  1  0.14  0.0  0.18  1.0

data_NbO2
_symmetry_space_group_name_H-M   P-1
_cell_length_a   3.96
_cell_length_b   6.88
_cell_length_c   6.91
_cell_angle_alpha   106.2
_cell_angle_beta   90.0
_cell_angle_gamma   106.72
_symmetry_Int_Tables_number   2
_chemical_formula_structural   NbO2
_chemical_formula_sum   'Nb4 O8'
_cell_volume   172.51
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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
  Nb  Nb0  2  0.0  0.3  0.86  1.0
  Nb  Nb1  2  0.0  0.41  0.09  1.0
  O  O2  2  0.0  0.22  0.22  1.0
  O  O3  2  0.0  0.43  0.81  1.0
  O  O4  2  0.0  0.45  0.62  1.0
  O  O5  2  0.0  0.46  0.52  1.0

Nb Nb Nb Nb O O O O O O O O
NbO2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one NbO2 cluster. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a single-bond geometry to one O(2) atom. The Nb(1)-O(2) bond length is 1.08 Å. In the second Nb site, Nb(2) is bonded in a 2-coordinate geometry to one O(2) and one O(3) atom. The Nb(2)-O(2) bond length is 1.13 Å. The Nb(2)-O(3) bond length is 1.79 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one O(2) and one O(4) atom. The O(1)-O(2) bond length is 1.33 Å. The O(1)-O(4) bond length is 0.73 Å. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Nb(1), one Nb(2), and one O(1) atom. In the third O site, O(3) is bonded in a single-bond geometry to one Nb(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one O(1) and one O(4) atom. The O(4)-O(4) bond length is 0.64 Å.