data_MgPb2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.11
_cell_length_b   9.11
_cell_length_c   9.11
_cell_angle_alpha   24.72
_cell_angle_beta   24.72
_cell_angle_gamma   24.72
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgPb2Se
_chemical_formula_sum   'Mg1 Pb2 Se1'
_cell_volume   116.18
_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
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Pb  Pb1  1  0.0  0.0  0.43  1.0
  Pb  Pb2  1  0.0  0.0  0.04  1.0
  Se  Se3  1  0.0  0.0  0.24  1.0

data_MgPb2Se
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.75
_cell_length_b   3.9
_cell_length_c   9.11
_cell_angle_alpha   90.0
_cell_angle_beta   104.31
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   MgPb2Se
_chemical_formula_sum   'Mg2 Pb4 Se2'
_cell_volume   232.35
_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
  Mg  Mg0  2  0.0  0.0  0.0  1.0
  Pb  Pb1  2  0.0  0.0  0.57  1.0
  Pb  Pb2  2  0.0  0.0  0.96  1.0
  Se  Se3  2  0.0  0.0  0.76  1.0

Mg Pb Pb Se
Mg Pb Pb Se 0 2 o o o 1 3 o o o 2 3 o o o 
MgPb2Se is Cyanogen Chloride-like structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two MgPb2Se clusters. Mg(1) is bonded in a single-bond geometry to one Pb(2) atom. The Mg(1)-Pb(2) bond length is 0.41 Å. There are two inequivalent Pb sites. In the first Pb site, Pb(1) is bonded in a single-bond geometry to one Se(1) atom. The Pb(1)-Se(1) bond length is 1.76 Å. In the second Pb site, Pb(2) is bonded in a single-bond geometry to one Mg(1) and one Se(1) atom. The Pb(2)-Se(1) bond length is 1.76 Å. Se(1) is bonded in a linear geometry to one Pb(1) and one Pb(2) atom.