data_Si3SnPb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.17
_cell_length_b   5.17
_cell_length_c   5.17
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si3SnPb
_chemical_formula_sum   'Si3 Sn1 Pb1'
_cell_volume   138.05
_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
  Si  Si1  1  0.0  0.58  0.0  1.0
  Si  Si2  1  0.0  0.0  0.58  1.0
  Si  Si3  1  0.58  0.0  0.0  1.0
  Sn  Sn4  1  0.0  0.0  0.0  1.0
  Pb  Pb0  1  0.58  0.58  0.58  1.0

data_Si3SnPb
_symmetry_space_group_name_H-M   R3m
_cell_length_a   7.31
_cell_length_b   7.31
_cell_length_c   8.95
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Si3SnPb
_chemical_formula_sum   'Si9 Sn3 Pb3'
_cell_volume   414.16
_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
  Si  Si0  9  0.06  0.53  0.53  1.0
  Sn  Sn1  3  0.0  0.0  0.0  1.0
  Pb  Pb2  3  0.0  0.0  0.58  1.0

Si Si Si Sn Pb
Si Si Si Sn Pb 0 3 o + o 0 4 o o - 0 4 - o o 0 4 - o - 1 3 o o + 1 4 o - o 1 4 - o o 1 4 - - o 2 3 + o o 2 4 o o - 2 4 o - o 2 4 o - - 3 4 - - - 
PbSnSi3 crystallizes in the trigonal R3m space group. Pb(1) is bonded in a 3-coordinate geometry to three equivalent Si(1) atoms. All Pb(1)-Si(1) bond lengths are 3.04 Å. Sn(1) is bonded to six equivalent Si(1) atoms to form distorted corner-sharing SnSi6 octahedra. The corner-sharing octahedra are not tilted. There are three shorter (2.15 Å) and three longer (3.02 Å) Sn(1)-Si(1) bond lengths. Si(1) is bonded in a distorted T-shaped geometry to one Pb(1) and two equivalent Sn(1) atoms.