data_NbPb3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.93
_cell_length_b   5.93
_cell_length_c   5.93
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NbPb3
_chemical_formula_sum   'Nb2 Pb6'
_cell_volume   208.46
_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  0.96  0.96  0.96  1.0
  Nb  Nb1  1  0.0  0.0  0.0  1.0
  Pb  Pb2  1  0.48  0.0  0.96  1.0
  Pb  Pb3  1  0.45  0.0  0.96  1.0
  Pb  Pb4  1  0.96  0.48  0.0  1.0
  Pb  Pb5  1  0.96  0.45  0.0  1.0
  Pb  Pb6  1  0.0  0.96  0.45  1.0
  Pb  Pb7  1  0.0  0.96  0.48  1.0

data_NbPb3
_symmetry_space_group_name_H-M   R3
_cell_length_a   8.39
_cell_length_b   8.39
_cell_length_c   10.27
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   NbPb3
_chemical_formula_sum   'Nb6 Pb18'
_cell_volume   625.38
_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  3  0.0  0.0  0.0  1.0
  Nb  Nb1  3  0.0  0.0  0.96  1.0
  Pb  Pb2  9  0.0  0.52  0.48  1.0
  Pb  Pb3  9  0.16  0.8  0.8  1.0

Nb Nb Pb Pb Pb Pb Pb Pb
NbPb3 crystallizes in the trigonal R3 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted single-bond geometry to one Nb(2) and three equivalent Pb(1) atoms. The Nb(1)-Nb(2) bond length is 0.36 Å. All Nb(1)-Pb(1) bond lengths are 2.87 Å. In the second Nb site, Nb(2) is bonded in a distorted single-bond geometry to one Nb(1) and three equivalent Pb(2) atoms. All Nb(2)-Pb(2) bond lengths are 2.66 Å. There are two inequivalent Pb sites. In the first Pb site, Pb(1) is bonded in a linear geometry to one Nb(1) and one Pb(2) atom. The Pb(1)-Pb(2) bond length is 0.21 Å. In the second Pb site, Pb(2) is bonded in a linear geometry to one Nb(2) and one Pb(1) atom.