data_Nb3Sb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.31
_cell_length_b   5.31
_cell_length_c   5.31
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Nb3Sb
_chemical_formula_sum   'Nb6 Sb2'
_cell_volume   149.89
_cell_formula_units_Z   2
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  0.33  0.0  0.66  1.0
  Nb  Nb1  1  0.98  0.0  0.66  1.0
  Nb  Nb2  1  0.0  0.66  0.33  1.0
  Nb  Nb3  1  0.0  0.66  0.98  1.0
  Nb  Nb4  1  0.66  0.98  0.0  1.0
  Nb  Nb5  1  0.66  0.33  0.0  1.0
  Sb  Sb6  1  0.0  0.0  0.0  1.0
  Sb  Sb7  1  0.66  0.66  0.66  1.0

data_Nb3Sb
_symmetry_space_group_name_H-M   R3
_cell_length_a   7.51
_cell_length_b   7.51
_cell_length_c   9.2
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   Nb3Sb
_chemical_formula_sum   'Nb18 Sb6'
_cell_volume   449.67
_cell_formula_units_Z   6
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  'x+1/3, y+2/3, z+2/3'
  5  '-y+1/3, x-y+2/3, z+2/3'
  6  '-x+y+1/3, -x+2/3, z+2/3'
  7  'x+2/3, y+1/3, z+1/3'
  8  '-y+2/3, x-y+1/3, z+1/3'
  9  '-x+y+2/3, -x+1/3, z+1/3'
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  9  0.0  0.67  0.33  1.0
  Nb  Nb1  9  0.1  0.22  0.88  1.0
  Sb  Sb2  3  0.0  0.0  0.0  1.0
  Sb  Sb3  3  0.0  0.0  0.66  1.0

Nb Nb Nb Nb Nb Nb Sb Sb
Nb3Sb crystallizes in the trigonal R3 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 4-coordinate geometry to two equivalent Nb(2), one Sb(1), and one Sb(2) atom. There is one shorter (1.83 Å) and one longer (2.53 Å) Nb(1)-Nb(2) bond length. The Nb(1)-Sb(1) bond length is 2.52 Å. The Nb(1)-Sb(2) bond length is 2.52 Å. In the second Nb site, Nb(2) is bonded in a distorted single-bond geometry to two equivalent Nb(1), one Sb(1), and one Sb(2) atom. The Nb(2)-Sb(1) bond length is 1.83 Å. The Nb(2)-Sb(2) bond length is 2.52 Å. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 3-coordinate geometry to three equivalent Nb(1) and three equivalent Nb(2) atoms. In the second Sb site, Sb(2) is bonded in a 6-coordinate geometry to three equivalent Nb(1) and three equivalent Nb(2) atoms.