data_SeBr3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.18
_cell_length_b   5.18
_cell_length_c   5.18
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SeBr3
_chemical_formula_sum   'Se1 Br3'
_cell_volume   98.1
_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
  Se  Se3  1  0.0  0.0  0.0  1.0
  Br  Br0  1  0.83  0.83  0.83  1.0
  Br  Br1  1  0.66  0.66  0.66  1.0
  Br  Br2  1  0.49  0.49  0.49  1.0

data_SeBr3
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.18
_cell_length_b   5.18
_cell_length_c   12.68
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   SeBr3
_chemical_formula_sum   'Se3 Br9'
_cell_volume   294.3
_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
  Se  Se0  3  0.0  0.0  0.0  1.0
  Br  Br1  3  0.0  0.0  0.17  1.0
  Br  Br2  3  0.0  0.0  0.34  1.0
  Br  Br3  3  0.0  0.0  0.51  1.0

Se Br Br Br
Se Br Br Br 0 1 - - - 1 2 o o o 2 3 o o o 
SeBr3 crystallizes in the trigonal R3m space group. Se(1) is bonded to one Br(1) and three equivalent Br(2) atoms to form distorted SeBr4 trigonal pyramids that share  a cornercorner with one Br(2)Se3Br2 trigonal bipyramid, corners with six equivalent Se(1)Br4 trigonal pyramids, and edges with three equivalent Br(3)Br4 trigonal pyramids. The Se(1)-Br(1) bond length is 2.15 Å. All Se(1)-Br(2) bond lengths are 2.99 Å. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded in a 2-coordinate geometry to one Se(1), one Br(2), and three equivalent Br(3) atoms. The Br(1)-Br(2) bond length is 2.15 Å. All Br(1)-Br(3) bond lengths are 2.99 Å. In the second Br site, Br(2) is bonded to three equivalent Se(1), one Br(1), and one Br(3) atom to form BrSe3Br2 trigonal bipyramids that share corners with six equivalent Br(2)Se3Br2 trigonal bipyramids,  a cornercorner with one Se(1)Br4 trigonal pyramid, and corners with three equivalent Br(3)Br4 trigonal pyramids. The Br(2)-Br(3) bond length is 2.15 Å. In the third Br site, Br(3) is bonded to one Br(2) and three equivalent Br(1) atoms to form distorted BrBr4 trigonal pyramids that share corners with three equivalent Br(2)Se3Br2 trigonal bipyramids, corners with six equivalent Br(3)Br4 trigonal pyramids, and edges with three equivalent Se(1)Br4 trigonal pyramids.