data_HgPbBr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.22
_cell_length_b   5.22
_cell_length_c   4.35
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HgPbBr2
_chemical_formula_sum   'Hg1 Pb1 Br2'
_cell_volume   118.64
_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
  Hg  Hg2  1  0.0  0.0  0.0  1.0
  Pb  Pb3  1  0.61  0.61  0.0  1.0
  Br  Br0  1  0.61  0.0  0.18  1.0
  Br  Br1  1  0.0  0.61  0.18  1.0

data_HgPbBr2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   7.38
_cell_length_b   7.38
_cell_length_c   4.35
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   HgPbBr2
_chemical_formula_sum   'Hg2 Pb2 Br4'
_cell_volume   237.29
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Hg  Hg0  2  0.0  0.0  0.0  1.0
  Pb  Pb1  2  0.11  0.5  -0.0  1.0
  Br  Br2  4  0.31  0.31  0.18  1.0

Hg Pb Br Br
Hg Pb Br Br 0 2 - o o 0 3 o - o 1 2 o + o 1 3 + o o 
HgPbBr2 is alpha Po structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two HgPbBr2 clusters. Hg(1) is bonded in an L-shaped geometry to two equivalent Br(1) atoms. Both Hg(1)-Br(1) bond lengths are 2.17 Å. Pb(1) is bonded in a distorted L-shaped geometry to two equivalent Br(1) atoms. Both Pb(1)-Br(1) bond lengths are 2.17 Å. Br(1) is bonded in a distorted L-shaped geometry to one Hg(1) and one Pb(1) atom.