data_AlCu2Hg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.12
_cell_length_b   3.35
_cell_length_c   5.91
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   AlCu2Hg
_chemical_formula_sum   'Al1 Cu2 Hg1'
_cell_volume   61.88
_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
  Al  Al0  1  0.0  0.0  0.69  1.0
  Cu  Cu1  1  0.56  0.68  0.03  1.0
  Cu  Cu2  1  0.0  0.0  0.26  1.0
  Hg  Hg3  1  0.56  0.68  0.88  1.0

data_AlCu2Hg
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.12
_cell_length_b   3.35
_cell_length_c   5.91
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   AlCu2Hg
_chemical_formula_sum   'Al1 Cu2 Hg1'
_cell_volume   61.88
_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
  Al  Al0  1  0.0  0.0  0.69  1.0
  Cu  Cu1  1  0.0  0.0  0.26  1.0
  Cu  Cu2  1  0.56  0.68  0.03  1.0
  Hg  Hg3  1  0.56  0.68  0.88  1.0

Al Cu Cu Hg
Al Cu Cu Hg 0 1 - - + 0 3 - - o 0 3 o - o 0 2 o o o 1 3 o o - 1 2 + + o 1 2 o + o 2 3 - - - 
Cu2HgAl crystallizes in the triclinic P1 space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a single-bond geometry to two equivalent Cu(2) and one Hg(1) atom. There is one shorter (2.25 Å) and one longer (2.50 Å) Cu(1)-Cu(2) bond length. The Cu(1)-Hg(1) bond length is 0.84 Å. In the second Cu site, Cu(2) is bonded in a 3-coordinate geometry to two equivalent Cu(1) and one Al(1) atom. The Cu(2)-Al(1) bond length is 2.54 Å. Hg(1) is bonded in a 1-coordinate geometry to one Cu(1) and four equivalent Al(1) atoms. There are a spread of Hg(1)-Al(1) bond distances ranging from 2.08-3.08 Å. Al(1) is bonded in a 5-coordinate geometry to one Cu(2) and four equivalent Hg(1) atoms.