data_Si4SnHg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.43
_cell_length_b   5.43
_cell_length_c   5.43
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si4SnHg
_chemical_formula_sum   'Si4 Sn1 Hg1'
_cell_volume   113.49
_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  0.88  0.88  0.8  1.0
  Si  Si2  1  0.88  0.8  0.88  1.0
  Si  Si3  1  0.8  0.88  0.88  1.0
  Si  Si4  1  0.8  0.8  0.8  1.0
  Sn  Sn5  1  0.0  0.0  0.0  1.0
  Hg  Hg0  1  0.92  0.92  0.92  1.0

data_Si4SnHg
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.43
_cell_length_b   5.43
_cell_length_c   13.31
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Si4SnHg
_chemical_formula_sum   'Si12 Sn3 Hg3'
_cell_volume   340.47
_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  0.05  0.03  0.14  1.0
  Si  Si1  3  0.0  0.0  0.2  1.0
  Sn  Sn2  3  0.0  0.0  0.0  1.0
  Hg  Hg3  3  0.0  0.0  0.08  1.0

Si Si Si Si Sn Hg
HgSnSi4 is Copper structured and crystallizes in the trigonal R3m space group. The structure is zero-dimensional and consists of three HgSnSi4 clusters. Hg(1) is bonded in a distorted rectangular see-saw-like geometry to one Sn(1) and three equivalent Si(1) atoms. The Hg(1)-Sn(1) bond length is 1.05 Å. All Hg(1)-Si(1) bond lengths are 0.90 Å. Sn(1) is bonded in a single-bond geometry to one Hg(1) atom. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 2-coordinate geometry to one Hg(1), one Si(2), and two equivalent Si(1) atoms. The Si(1)-Si(2) bond length is 0.76 Å. Both Si(1)-Si(1) bond lengths are 0.44 Å. In the second Si site, Si(2) is bonded in a 3-coordinate geometry to three equivalent Si(1) atoms.