data_Nb2C
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.0
_cell_length_b   3.11
_cell_length_c   5.0
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Nb2C
_chemical_formula_sum   'Nb8 C4'
_cell_volume   170.83
_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  Nb4  1  0.74  0.78  0.32  1.0
  Nb  Nb5  1  0.24  0.78  0.18  1.0
  Nb  Nb6  1  1.0  0.78  0.76  1.0
  Nb  Nb7  1  0.5  0.78  0.73  1.0
  Nb  Nb8  1  0.5  0.33  0.27  1.0
  Nb  Nb9  1  1.0  0.33  0.23  1.0
  Nb  Nb10  1  0.76  0.33  0.82  1.0
  Nb  Nb11  1  0.26  0.33  0.68  1.0
  C  C0  1  0.62  0.78  0.54  1.0
  C  C1  1  0.12  0.78  0.96  1.0
  C  C2  1  0.37  0.33  0.46  1.0
  C  C3  1  0.87  0.33  0.04  1.0

data_Nb2C
_symmetry_space_group_name_H-M   P2_1/c
_cell_length_a   3.11
_cell_length_b   5.0
_cell_length_c   11.0
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   14
_chemical_formula_structural   Nb2C
_chemical_formula_sum   'Nb8 C4'
_cell_volume   170.83
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-x, -y, -z'
  3  '-x, y+1/2, -z+1/2'
  4  'x, -y+1/2, z+1/2'
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  4  0.28  0.24  0.5  1.0
  Nb  Nb1  4  0.28  0.68  0.76  1.0
  C  C2  4  0.28  0.04  0.37  1.0

Nb Nb Nb Nb Nb Nb Nb Nb C C C C
Nb2C crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of four Nb2C clusters. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted single-bond geometry to one C(1) atom. The Nb(1)-C(1) bond length is 1.67 Å. In the second Nb site, Nb(4) is bonded in a distorted single-bond geometry to one C(1) atom. The Nb(4)-C(1) bond length is 1.67 Å. C(1) is bonded in a distorted linear geometry to one Nb(1) and one Nb(4) atom.