data_Mg5Cu
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.69
_cell_length_b   5.69
_cell_length_c   7.35
_cell_angle_alpha   109.14
_cell_angle_beta   109.14
_cell_angle_gamma   33.11
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg5Cu
_chemical_formula_sum   'Mg5 Cu1'
_cell_volume   122.13
_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
  Mg  Mg1  1  0.64  0.0  0.45  1.0
  Mg  Mg2  1  0.75  0.0  0.49  1.0
  Mg  Mg3  1  0.47  0.0  0.95  1.0
  Mg  Mg4  1  0.39  0.0  0.77  1.0
  Mg  Mg5  1  0.32  0.0  0.52  1.0
  Cu  Cu0  1  0.29  0.0  0.67  1.0

data_Mg5Cu
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.24
_cell_length_b   5.69
_cell_length_c   7.35
_cell_angle_alpha   109.14
_cell_angle_beta   90.0
_cell_angle_gamma   106.56
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg5Cu
_chemical_formula_sum   'Mg5 Cu1'
_cell_volume   122.13
_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
  Mg  Mg0  1  0.0  0.25  0.51  1.0
  Mg  Mg1  1  0.0  0.36  0.55  1.0
  Mg  Mg2  1  0.0  0.53  0.05  1.0
  Mg  Mg3  1  0.0  0.61  0.23  1.0
  Mg  Mg4  1  0.0  0.68  0.48  1.0
  Cu  Cu5  1  0.0  0.71  0.33  1.0

Mg Mg Mg Mg Mg Cu
Mg Mg Mg Mg Mg Cu 0 1 o o o 2 3 o o o 3 5 o o o 4 5 o o o 
(Mg)2MgMg2Cu crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one magnesiomagnesium molecule and one MgMg2Cu cluster. In the MgMg2Cu cluster, there are three inequivalent Mg sites. In the first Mg site, Mg(3) is bonded in a single-bond geometry to one Mg(4) atom. The Mg(3)-Mg(4) bond length is 1.27 Å. In the second Mg site, Mg(4) is bonded in a single-bond geometry to one Mg(3) and one Cu(1) atom. The Mg(4)-Cu(1) bond length is 0.77 Å. In the third Mg site, Mg(5) is bonded in a single-bond geometry to one Cu(1) atom. The Mg(5)-Cu(1) bond length is 1.22 Å. Cu(1) is bonded in a bent 120 degrees geometry to one Mg(4) and one Mg(5) atom.