data_NbPbSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.76
_cell_length_b   4.76
_cell_length_c   4.76
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NbPbSe
_chemical_formula_sum   'Nb1 Pb1 Se1'
_cell_volume   76.18
_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
  Nb  Nb0  1  0.05  0.05  0.05  1.0
  Pb  Pb1  1  0.36  0.36  0.36  1.0
  Se  Se2  1  0.0  0.0  0.0  1.0

data_NbPbSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.76
_cell_length_b   4.76
_cell_length_c   11.66
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   NbPbSe
_chemical_formula_sum   'Nb3 Pb3 Se3'
_cell_volume   228.55
_cell_formula_units_Z   3
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  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+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  0.95  1.0
  Pb  Pb1  3  0.0  0.0  0.64  1.0
  Se  Se2  3  0.0  0.0  0.0  1.0

Nb Pb Se
Nb Pb Se 0 2 o o o 0 1 o o - 0 1 o - o 0 1 - o o 1 2 o o + 1 2 o + o 1 2 + o o 
NbPbSe crystallizes in the trigonal R3m space group. Nb(1) is bonded in a single-bond geometry to four equivalent Pb(1) and one Se(1) atom. There are three shorter (2.75 Å) and one longer (3.70 Å) Nb(1)-Pb(1) bond length. The Nb(1)-Se(1) bond length is 0.55 Å. Pb(1) is bonded to four equivalent Nb(1) and three equivalent Se(1) atoms to form a mixture of corner and edge-sharing PbNb4Se3 hexagonal pyramids. All Pb(1)-Se(1) bond lengths are 2.77 Å. Se(1) is bonded in a single-bond geometry to one Nb(1) and three equivalent Pb(1) atoms.