data_AlCu
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.77
_cell_length_b   2.77
_cell_length_c   8.35
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   AlCu
_chemical_formula_sum   'Al2 Cu2'
_cell_volume   55.5
_cell_formula_units_Z   2
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  0.39  0.8  0.19  1.0
  Al  Al1  1  0.0  0.6  0.16  1.0
  Cu  Cu2  1  0.39  0.8  0.17  1.0
  Cu  Cu3  1  0.0  0.6  0.19  1.0

data_AlCu
_symmetry_space_group_name_H-M   C2/m
_cell_length_a   4.8
_cell_length_b   2.77
_cell_length_c   8.35
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   12
_chemical_formula_structural   AlCu
_chemical_formula_sum   'Al4 Cu4'
_cell_volume   111.01
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-x, -y, -z'
  3  '-x, y, -z'
  4  'x, -y, z'
  5  'x+1/2, y+1/2, z'
  6  '-x+1/2, -y+1/2, -z'
  7  '-x+1/2, y+1/2, -z'
  8  '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
  Al  Al0  4  0.09  0.0  0.02  1.0
  Cu  Cu1  4  0.09  0.0  0.99  1.0

Al Al Cu Cu
CuAl is alpha carbon monoxide-like structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two aluminium--copper (1/1) molecules. Cu(1) is bonded in a single-bond geometry to one Al(1) atom. The Cu(1)-Al(1) bond length is 0.23 Å. Al(1) is bonded in a single-bond geometry to one Cu(1) atom.