data_NaSe2Br
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.14
_cell_length_b   5.14
_cell_length_c   5.14
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaSe2Br
_chemical_formula_sum   'Na1 Se2 Br1'
_cell_volume   95.94
_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  Na1  1  0.0  0.0  0.0  1.0
  Se  Se2  1  0.45  0.45  0.45  1.0
  Se  Se3  1  0.63  0.63  0.63  1.0
  Br  Br0  1  0.82  0.82  0.82  1.0

data_NaSe2Br
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.14
_cell_length_b   5.14
_cell_length_c   12.59
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   NaSe2Br
_chemical_formula_sum   'Na3 Se6 Br3'
_cell_volume   287.82
_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
  Na  Na0  3  0.0  0.0  0.0  1.0
  Se  Se1  3  0.0  0.0  0.37  1.0
  Se  Se2  3  0.0  0.0  0.55  1.0
  Br  Br3  3  0.0  0.0  0.18  1.0

Na Se Se Br
Na Se Se Br 0 3 - - - 1 2 o o o 2 3 o o o 
NaSe2Br crystallizes in the trigonal R3m space group. Na(1) is bonded in a distorted single-bond geometry to three equivalent Se(1), three equivalent Se(2), and one Br(1) atom. All Na(1)-Se(1) bond lengths are 3.31 Å. All Na(1)-Se(2) bond lengths are 3.00 Å. The Na(1)-Br(1) bond length is 2.31 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Na(1), one Se(2), and three equivalent Br(1) atoms to form distorted SeNa3SeBr3 hexagonal pyramids that share corners with three equivalent Se(2)Na3SeBr trigonal bipyramids, edges with six equivalent Se(1)Na3SeBr3 hexagonal pyramids, and faces with three equivalent Se(2)Na3SeBr trigonal bipyramids. The Se(1)-Se(2) bond length is 2.31 Å. All Se(1)-Br(1) bond lengths are 3.00 Å. In the second Se site, Se(2) is bonded to three equivalent Na(1), one Se(1), and one Br(1) atom to form distorted SeNa3SeBr trigonal bipyramids that share corners with three equivalent Se(1)Na3SeBr3 hexagonal pyramids, corners with six equivalent Se(2)Na3SeBr trigonal bipyramids, and faces with three equivalent Se(1)Na3SeBr3 hexagonal pyramids. The Se(2)-Br(1) bond length is 2.31 Å. Br(1) is bonded in a distorted linear geometry to one Na(1), one Se(2), and three equivalent Se(1) atoms.