data_FeHg4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.21
_cell_length_b   6.21
_cell_length_c   6.21
_cell_angle_alpha   93.34
_cell_angle_beta   93.34
_cell_angle_gamma   152.05
_symmetry_Int_Tables_number   1
_chemical_formula_structural   FeHg4
_chemical_formula_sum   'Fe1 Hg4'
_cell_volume   108.74
_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
  Fe  Fe0  1  0.0  0.0  0.0  1.0
  Hg  Hg1  1  0.98  0.26  0.0  1.0
  Hg  Hg2  1  0.26  0.98  0.0  1.0
  Hg  Hg3  1  0.0  0.28  0.5  1.0
  Hg  Hg4  1  0.28  0.0  0.5  1.0

data_FeHg4
_symmetry_space_group_name_H-M   Cm
_cell_length_a   3.0
_cell_length_b   12.04
_cell_length_c   6.21
_cell_angle_alpha   90.0
_cell_angle_beta   103.98
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   FeHg4
_chemical_formula_sum   'Fe2 Hg8'
_cell_volume   217.47
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Fe  Fe0  2  0.0  0.0  0.0  1.0
  Hg  Hg1  4  0.36  0.14  0.5  1.0
  Hg  Hg2  4  0.38  0.36  -0.0  1.0

Fe Hg Hg Hg Hg
Fe Hg Hg Hg Hg 0 1 - o o 0 2 o - o 0 3 o o o 0 3 o o - 0 4 o o o 0 4 o o - 1 3 + o o 1 3 + o - 2 4 o + o 2 4 o + - 3 4 - o o 3 4 o + o 3 4 o o o 3 3 + + o 4 4 + + o 
FeHg4 crystallizes in the monoclinic Cm space group. Fe(1) is bonded in a bent 150 degrees geometry to two equivalent Hg(1) and two equivalent Hg(2) atoms. Both Fe(1)-Hg(1) bond lengths are 1.71 Å. Both Fe(1)-Hg(2) bond lengths are 3.46 Å. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a single-bond geometry to one Fe(1) and two equivalent Hg(2) atoms. There is one shorter (3.08 Å) and one longer (3.12 Å) Hg(1)-Hg(2) bond length. In the second Hg site, Hg(2) is bonded to one Fe(1), two equivalent Hg(1), and five equivalent Hg(2) atoms to form a mixture of distorted corner and edge-sharing HgFeHg7 hexagonal bipyramids. There are a spread of Hg(2)-Hg(2) bond distances ranging from 3.00-3.35 Å.