data_BeCuHg2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.14
_cell_length_b   3.14
_cell_length_c   6.52
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   BeCuHg2
_chemical_formula_sum   'Be1 Cu1 Hg2'
_cell_volume   64.3
_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
  Be  Be0  1  0.0  0.0  0.0  1.0
  Cu  Cu1  1  0.0  0.0  0.26  1.0
  Hg  Hg2  1  0.57  0.57  0.97  1.0
  Hg  Hg3  1  0.57  0.57  0.56  1.0

data_BeCuHg2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.44
_cell_length_b   4.44
_cell_length_c   6.52
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   BeCuHg2
_chemical_formula_sum   'Be2 Cu2 Hg4'
_cell_volume   128.59
_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
  Be  Be0  2  0.0  0.0  0.0  1.0
  Cu  Cu1  2  0.0  0.0  0.26  1.0
  Hg  Hg2  2  0.07  0.5  0.56  1.0
  Hg  Hg3  2  0.07  0.5  0.97  1.0

Be Cu Hg Hg
BeCuHg2 crystallizes in the monoclinic Cm space group. Be(1) is bonded to one Cu(1) and four equivalent Hg(1) atoms to form a mixture of distorted corner and edge-sharing BeCuHg4 square pyramids. The Be(1)-Cu(1) bond length is 1.71 Å. There are a spread of Be(1)-Hg(1) bond distances ranging from 1.92-2.54 Å. Cu(1) is bonded in a single-bond geometry to one Be(1) and four equivalent Hg(2) atoms. There are a spread of Cu(1)-Hg(2) bond distances ranging from 2.71-3.18 Å. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 4-coordinate geometry to four equivalent Be(1) and one Hg(2) atom. The Hg(1)-Hg(2) bond length is 2.67 Å. In the second Hg site, Hg(2) is bonded in a 9-coordinate geometry to four equivalent Cu(1), one Hg(1), and four equivalent Hg(2) atoms. All Hg(2)-Hg(2) bond lengths are 3.14 Å.