data_Ba2MgCu
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.89
_cell_length_b   3.89
_cell_length_c   9.55
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ba2MgCu
_chemical_formula_sum   'Ba2 Mg1 Cu1'
_cell_volume   144.89
_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
  Ba  Ba0  1  0.95  0.95  0.91  1.0
  Ba  Ba1  1  0.0  0.0  0.17  1.0
  Mg  Mg3  1  0.0  0.0  0.46  1.0
  Cu  Cu2  1  0.95  0.95  0.35  1.0

data_Ba2MgCu
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.51
_cell_length_b   5.51
_cell_length_c   9.55
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Ba2MgCu
_chemical_formula_sum   'Ba4 Mg2 Cu2'
_cell_volume   289.79
_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
  Ba  Ba0  2  0.0  0.0  0.17  1.0
  Ba  Ba1  2  0.45  0.5  0.91  1.0
  Mg  Mg2  2  0.0  0.0  0.46  1.0
  Cu  Cu3  2  0.45  0.5  0.35  1.0

Ba Ba Mg Cu
Ba2MgCu crystallizes in the monoclinic Cm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to one Ba(2), four equivalent Ba(1), and one Mg(1) atom to form a mixture of distorted corner and edge-sharing BaBa5Mg octahedra. The corner-sharing octahedra are not tilted. The Ba(1)-Ba(2) bond length is 2.49 Å. All Ba(1)-Ba(1) bond lengths are 3.89 Å. The Ba(1)-Mg(1) bond length is 4.25 Å. In the second Ba site, Ba(2) is bonded in a single-bond geometry to one Ba(1) and one Cu(1) atom. The Ba(2)-Cu(1) bond length is 1.77 Å. Mg(1) is bonded in a single-bond geometry to one Ba(1) and one Cu(1) atom. The Mg(1)-Cu(1) bond length is 1.13 Å. Cu(1) is bonded in a bent 150 degrees geometry to one Ba(2) and one Mg(1) atom.