data_TaSiHg3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.0
_cell_length_b   5.0
_cell_length_c   5.0
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   TaSiHg3
_chemical_formula_sum   'Ta1 Si1 Hg3'
_cell_volume   124.88
_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
  Ta  Ta4  1  0.5  0.5  0.5  1.0
  Si  Si0  1  0.0  0.0  0.0  1.0
  Hg  Hg1  1  0.0  0.5  0.0  1.0
  Hg  Hg2  1  0.0  0.0  0.5  1.0
  Hg  Hg3  1  0.5  0.0  0.0  1.0

data_TaSiHg3
_symmetry_space_group_name_H-M   Pm-3m
_cell_length_a   5.0
_cell_length_b   5.0
_cell_length_c   5.0
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   221
_chemical_formula_structural   TaSiHg3
_chemical_formula_sum   'Ta1 Si1 Hg3'
_cell_volume   124.88
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-x, -y, -z'
  3  '-y, x, z'
  4  'y, -x, -z'
  5  '-x, -y, z'
  6  'x, y, -z'
  7  'y, -x, z'
  8  '-y, x, -z'
  9  'x, -y, -z'
  10  '-x, y, z'
  11  '-y, -x, -z'
  12  'y, x, z'
  13  '-x, y, -z'
  14  'x, -y, z'
  15  'y, x, -z'
  16  '-y, -x, z'
  17  'z, x, y'
  18  '-z, -x, -y'
  19  'z, -y, x'
  20  '-z, y, -x'
  21  'z, -x, -y'
  22  '-z, x, y'
  23  'z, y, -x'
  24  '-z, -y, x'
  25  '-z, x, -y'
  26  'z, -x, y'
  27  '-z, -y, -x'
  28  'z, y, x'
  29  '-z, -x, y'
  30  'z, x, -y'
  31  '-z, y, x'
  32  'z, -y, -x'
  33  'y, z, x'
  34  '-y, -z, -x'
  35  'x, z, -y'
  36  '-x, -z, y'
  37  '-y, z, -x'
  38  'y, -z, x'
  39  '-x, z, y'
  40  'x, -z, -y'
  41  '-y, -z, x'
  42  'y, z, -x'
  43  '-x, -z, -y'
  44  'x, z, y'
  45  'y, -z, -x'
  46  '-y, z, x'
  47  'x, -z, y'
  48  '-x, z, -y'
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
  Ta  Ta0  1  0.0  0.0  0.0  1.0
  Si  Si1  1  0.5  0.5  0.5  1.0
  Hg  Hg2  3  0.0  0.5  0.5  1.0

Ta Si Hg Hg Hg
TaHg3Si is (Cubic) Perovskite structured and crystallizes in the trigonal R3m space group. Ta(1) is bonded to twelve equivalent Hg(1) atoms to form TaHg12 cuboctahedra that share corners with twelve equivalent Ta(1)Hg12 cuboctahedra, faces with six equivalent Ta(1)Hg12 cuboctahedra, and faces with eight equivalent Si(1)Hg6 octahedra. There are nine shorter (3.53 Å) and three longer (3.54 Å) Ta(1)-Hg(1) bond lengths. Hg(1) is bonded to four equivalent Ta(1) and two equivalent Si(1) atoms to form a mixture of distorted corner, edge, and face-sharing HgTa4Si2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. Both Hg(1)-Si(1) bond lengths are 2.50 Å. Si(1) is bonded to six equivalent Hg(1) atoms to form SiHg6 octahedra that share corners with six equivalent Si(1)Hg6 octahedra and faces with eight equivalent Ta(1)Hg12 cuboctahedra. The corner-sharing octahedra are not tilted.