data_SiSnHg2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.04
_cell_length_b   5.04
_cell_length_c   5.04
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SiSnHg2
_chemical_formula_sum   'Si1 Sn1 Hg2'
_cell_volume   90.6
_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  Si2  1  0.0  0.0  0.0  1.0
  Sn  Sn3  1  0.56  0.56  0.56  1.0
  Hg  Hg0  1  0.35  0.35  0.35  1.0
  Hg  Hg1  1  0.78  0.78  0.78  1.0

data_SiSnHg2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.04
_cell_length_b   5.04
_cell_length_c   12.35
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   SiSnHg2
_chemical_formula_sum   'Si3 Sn3 Hg6'
_cell_volume   271.79
_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  3  0.0  0.0  0.0  1.0
  Sn  Sn1  3  0.0  0.0  0.44  1.0
  Hg  Hg2  3  0.0  0.0  0.22  1.0
  Hg  Hg3  3  0.0  0.0  0.65  1.0

Si Sn Hg Hg
Hg2SnSi is Heusler structured and crystallizes in the trigonal R3m space group. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 10-coordinate geometry to three equivalent Hg(2), four equivalent Sn(1), and three equivalent Si(1) atoms. All Hg(1)-Hg(2) bond lengths are 3.17 Å. There is one shorter (2.69 Å) and three longer (3.24 Å) Hg(1)-Sn(1) bond lengths. All Hg(1)-Si(1) bond lengths are 2.92 Å. In the second Hg site, Hg(2) is bonded in a distorted linear geometry to three equivalent Hg(1), four equivalent Sn(1), and one Si(1) atom. There is one shorter (2.69 Å) and three longer (3.24 Å) Hg(2)-Sn(1) bond lengths. The Hg(2)-Si(1) bond length is 2.69 Å. Sn(1) is bonded in a distorted linear geometry to four equivalent Hg(1), four equivalent Hg(2), and three equivalent Si(1) atoms. All Sn(1)-Si(1) bond lengths are 3.17 Å. Si(1) is bonded to one Hg(2), three equivalent Hg(1), and three equivalent Sn(1) atoms to form distorted edge-sharing SiSn3Hg4 trigonal pyramids.