data_Cr2Hg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.32
_cell_length_b   5.32
_cell_length_c   5.32
_cell_angle_alpha   146.99
_cell_angle_beta   146.99
_cell_angle_gamma   47.38
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Cr2Hg
_chemical_formula_sum   'Cr2 Hg1'
_cell_volume   44.56
_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
  Cr  Cr0  1  0.0  0.0  0.82  1.0
  Cr  Cr1  1  0.0  0.0  0.92  1.0
  Hg  Hg2  1  0.0  0.0  0.0  1.0

data_Cr2Hg
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.28
_cell_length_b   4.28
_cell_length_c   5.32
_cell_angle_alpha   90.0
_cell_angle_beta   113.69
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Cr2Hg
_chemical_formula_sum   'Cr4 Hg2'
_cell_volume   89.12
_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
  Cr  Cr0  2  0.0  0.0  0.08  1.0
  Cr  Cr1  2  0.0  0.0  0.18  1.0
  Hg  Hg2  2  0.0  0.0  0.0  1.0

Cr Cr Hg
HgCr2 crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two HgCr2 clusters. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a single-bond geometry to one Cr(2) atom. The Cr(1)-Cr(2) bond length is 0.54 Å. In the second Cr site, Cr(2) is bonded in a distorted linear geometry to one Cr(1) and one Hg(1) atom. The Cr(2)-Hg(1) bond length is 0.40 Å. Hg(1) is bonded in a single-bond geometry to one Cr(2) atom.