data_CuSiAu2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.36
_cell_length_b   3.36
_cell_length_c   5.65
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CuSiAu2
_chemical_formula_sum   'Cu1 Si1 Au2'
_cell_volume   63.61
_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
  Cu  Cu2  1  0.0  0.0  0.82  1.0
  Si  Si3  1  0.0  0.0  0.0  1.0
  Au  Au0  1  0.68  0.68  0.43  1.0
  Au  Au1  1  0.68  0.68  0.22  1.0

data_CuSiAu2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.75
_cell_length_b   4.75
_cell_length_c   5.65
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   CuSiAu2
_chemical_formula_sum   'Cu2 Si2 Au4'
_cell_volume   127.22
_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
  Si  Si0  2  0.0  0.0  0.0  1.0
  Cu  Cu1  2  0.0  0.0  0.82  1.0
  Au  Au2  2  0.18  0.5  0.22  1.0
  Au  Au3  2  0.18  0.5  0.43  1.0

Cu Si Au Au
Cu Si Au Au 0 1 o o + 2 3 o o o 
Au2CuSi crystallizes in the monoclinic Cm space group. There are two inequivalent Au sites. In the first Au site, Au(1) is bonded in a distorted bent 150 degrees geometry to one Au(2) and one Cu(1) atom. The Au(1)-Au(2) bond length is 1.14 Å. The Au(1)-Cu(1) bond length is 2.72 Å. In the second Au site, Au(2) is bonded in a 4-coordinate geometry to one Au(1) and three equivalent Si(1) atoms. There is one shorter (1.98 Å) and two longer (2.82 Å) Au(2)-Si(1) bond lengths. Cu(1) is bonded in a distorted bent 150 degrees geometry to one Au(1) and one Si(1) atom. The Cu(1)-Si(1) bond length is 0.99 Å. Si(1) is bonded in a 4-coordinate geometry to three equivalent Au(2) and one Cu(1) atom.