data_Nb2TlSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.84
_cell_length_b   4.84
_cell_length_c   4.84
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Nb2TlSe
_chemical_formula_sum   'Nb2 Tl1 Se1'
_cell_volume   80.09
_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  0.42  0.42  0.42  1.0
  Nb  Nb1  1  0.71  0.71  0.71  1.0
  Tl  Tl3  1  0.13  0.13  0.13  1.0
  Se  Se2  1  0.0  0.0  0.0  1.0

data_Nb2TlSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.84
_cell_length_b   4.84
_cell_length_c   11.85
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Nb2TlSe
_chemical_formula_sum   'Nb6 Tl3 Se3'
_cell_volume   240.28
_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  0.29  1.0
  Nb  Nb1  3  0.0  0.0  0.58  1.0
  Tl  Tl2  3  0.0  0.0  0.87  1.0
  Se  Se3  3  0.0  0.0  0.0  1.0

Nb Nb Tl Se
Nb Nb Tl Se 0 3 o o + 0 3 o + o 0 3 + o o 0 2 o o + 0 2 o + o 0 2 + o o 0 1 - o o 0 1 o - o 0 1 o o - 1 3 o + + 1 3 + o + 1 3 + + o 1 2 o + + 1 2 + o + 1 2 + + o 2 3 o o o 
Nb2TlSe crystallizes in the trigonal R3m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 11-coordinate geometry to four equivalent Nb(2), four equivalent Tl(1), and three equivalent Se(1) atoms. There are three shorter (2.84 Å) and one longer (3.43 Å) Nb(1)-Nb(2) bond length. There are three shorter (2.84 Å) and one longer (3.43 Å) Nb(1)-Tl(1) bond length. All Nb(1)-Se(1) bond lengths are 2.98 Å. In the second Nb site, Nb(2) is bonded in a 11-coordinate geometry to four equivalent Nb(1), three equivalent Tl(1), and four equivalent Se(1) atoms. All Nb(2)-Tl(1) bond lengths are 2.98 Å. There are three shorter (2.84 Å) and one longer (3.43 Å) Nb(2)-Se(1) bond length. Tl(1) is bonded in a single-bond geometry to three equivalent Nb(2), four equivalent Nb(1), and one Se(1) atom. The Tl(1)-Se(1) bond length is 1.56 Å. Se(1) is bonded in a single-bond geometry to three equivalent Nb(1), four equivalent Nb(2), and one Tl(1) atom.