data_MgSi2Bi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.38
_cell_length_b   3.38
_cell_length_c   7.47
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgSi2Bi
_chemical_formula_sum   'Mg1 Si2 Bi1'
_cell_volume   85.33
_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  Mg1  1  0.0  0.0  0.93  1.0
  Si  Si2  1  0.69  0.69  0.36  1.0
  Si  Si3  1  0.0  0.0  0.2  1.0
  Bi  Bi0  1  0.69  0.69  0.71  1.0

data_MgSi2Bi
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.78
_cell_length_b   4.78
_cell_length_c   7.47
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   MgSi2Bi
_chemical_formula_sum   'Mg2 Si4 Bi2'
_cell_volume   170.65
_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  0.93  1.0
  Si  Si1  2  0.0  0.0  0.2  1.0
  Si  Si2  2  0.19  0.5  0.36  1.0
  Bi  Bi3  2  0.19  0.5  0.71  1.0

Mg Si Si Bi
MgSi2Bi crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 2-coordinate geometry to one Si(2) and one Bi(1) atom. The Mg(1)-Si(2) bond length is 2.05 Å. The Mg(1)-Bi(1) bond length is 2.24 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted bent 120 degrees geometry to three equivalent Si(2) and one Bi(1) atom. There is one shorter (1.89 Å) and two longer (2.81 Å) Si(1)-Si(2) bond lengths. The Si(1)-Bi(1) bond length is 2.58 Å. In the second Si site, Si(2) is bonded in a 2-coordinate geometry to one Mg(1) and three equivalent Si(1) atoms. Bi(1) is bonded in a 1-coordinate geometry to one Mg(1) and one Si(1) atom.