data_Na2Nb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.88
_cell_length_b   5.88
_cell_length_c   5.88
_cell_angle_alpha   154.83
_cell_angle_beta   123.11
_cell_angle_gamma   63.17
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2Nb
_chemical_formula_sum   'Na2 Nb1'
_cell_volume   71.97
_cell_formula_units_Z   1
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
  Na  Na0  1  0.0  0.0  0.34  1.0
  Na  Na1  1  0.0  0.0  0.68  1.0
  Nb  Nb2  1  0.0  0.0  0.0  1.0

data_Na2Nb
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.56
_cell_length_b   5.6
_cell_length_c   5.88
_cell_angle_alpha   118.45
_cell_angle_beta   102.58
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2Nb
_chemical_formula_sum   'Na2 Nb1'
_cell_volume   71.97
_cell_formula_units_Z   1
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
  Na  Na0  1  0.0  0.34  0.34  1.0
  Na  Na1  1  0.0  0.68  0.68  1.0
  Nb  Nb2  1  0.0  0.0  0.0  1.0

Na Na Nb
Na2Nb crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one Na2Nb cluster. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted single-bond geometry to one Nb(1) atom. The Na(1)-Nb(1) bond length is 2.02 Å. In the second Na site, Na(2) is bonded in a distorted single-bond geometry to one Nb(1) atom. The Na(2)-Nb(1) bond length is 1.90 Å. Nb(1) is bonded in a linear geometry to one Na(1) and one Na(2) atom.