data_PmSiSn2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.25
_cell_length_b   5.25
_cell_length_c   5.25
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   PmSiSn2
_chemical_formula_sum   'Pm1 Si1 Sn2'
_cell_volume   102.03
_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
  Pm  Pm0  1  0.71  0.71  0.71  1.0
  Si  Si1  1  0.0  0.0  0.0  1.0
  Sn  Sn2  1  0.85  0.85  0.85  1.0
  Sn  Sn3  1  0.56  0.56  0.56  1.0

data_PmSiSn2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.25
_cell_length_b   5.25
_cell_length_c   12.85
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   PmSiSn2
_chemical_formula_sum   'Pm3 Si3 Sn6'
_cell_volume   306.1
_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
  Pm  Pm0  3  0.0  0.0  0.29  1.0
  Si  Si1  3  0.0  0.0  0.0  1.0
  Sn  Sn2  3  0.0  0.0  0.15  1.0
  Sn  Sn3  3  0.0  0.0  0.44  1.0

Pm Si Sn Sn
Pm Si Sn Sn 0 3 o o o 0 2 o o o 1 2 - - - 
PmSn2Si crystallizes in the trigonal R3m space group. Pm(1) is bonded in a distorted linear geometry to one Sn(1), one Sn(2), and three equivalent Si(1) atoms. The Pm(1)-Sn(1) bond length is 1.87 Å. The Pm(1)-Sn(2) bond length is 1.87 Å. All Pm(1)-Si(1) bond lengths are 3.08 Å. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a distorted linear geometry to one Pm(1) and one Si(1) atom. The Sn(1)-Si(1) bond length is 1.87 Å. In the second Sn site, Sn(2) is bonded in a single-bond geometry to one Pm(1) atom. Si(1) is bonded to three equivalent Pm(1) and one Sn(1) atom to form distorted corner-sharing SiPm3Sn trigonal pyramids.