data_MgCu2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.68
_cell_length_b   4.68
_cell_length_c   6.59
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   85.6
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgCu2Se
_chemical_formula_sum   'Mg2 Cu4 Se2'
_cell_volume   143.99
_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
  Mg  Mg4  1  0.0  0.0  0.0  1.0
  Mg  Mg5  1  0.0  0.0  0.3  1.0
  Cu  Cu0  1  0.62  0.38  0.95  1.0
  Cu  Cu1  1  0.25  0.62  0.65  1.0
  Cu  Cu2  1  0.25  0.38  0.95  1.0
  Cu  Cu3  1  0.62  0.62  0.65  1.0
  Se  Se6  1  0.43  0.04  0.95  1.0
  Se  Se7  1  0.43  0.96  0.65  1.0

data_MgCu2Se
_symmetry_space_group_name_H-M   P1
_cell_length_a   4.68
_cell_length_b   4.68
_cell_length_c   6.59
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   94.4
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgCu2Se
_chemical_formula_sum   'Mg2 Cu4 Se2'
_cell_volume   143.99
_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
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Mg  Mg1  1  0.0  0.0  0.7  1.0
  Cu  Cu2  1  0.25  0.38  0.35  1.0
  Cu  Cu3  1  0.25  0.62  0.05  1.0
  Cu  Cu4  1  0.62  0.38  0.35  1.0
  Cu  Cu5  1  0.62  0.62  0.05  1.0
  Se  Se6  1  0.43  0.04  0.35  1.0
  Se  Se7  1  0.43  0.96  0.05  1.0

Mg Mg Cu Cu Cu Cu Se Se
MgCu2Se is Indium-like structured and crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one MgCu2Se cluster. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 1-coordinate geometry to one Mg(2) and one Se(1) atom. The Mg(1)-Mg(2) bond length is 1.96 Å. The Mg(1)-Se(1) bond length is 2.09 Å. In the second Mg site, Mg(2) is bonded in a 3-coordinate geometry to one Mg(1), one Cu(2), and one Se(2) atom. The Mg(2)-Cu(2) bond length is 3.09 Å. The Mg(2)-Se(2) bond length is 3.08 Å. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 1-coordinate geometry to one Se(1) atom. The Cu(1)-Se(1) bond length is 1.86 Å. In the second Cu site, Cu(2) is bonded in a distorted single-bond geometry to one Mg(2) and one Se(2) atom. The Cu(2)-Se(2) bond length is 1.86 Å. In the third Cu site, Cu(3) is bonded in a 1-coordinate geometry to one Se(1) atom. The Cu(3)-Se(1) bond length is 1.75 Å. In the fourth Cu site, Cu(4) is bonded in a distorted single-bond geometry to one Se(2) atom. The Cu(4)-Se(2) bond length is 1.75 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 3-coordinate geometry to one Mg(1), one Cu(1), and one Cu(3) atom. In the second Se site, Se(2) is bonded in a 2-coordinate geometry to one Mg(2), one Cu(2), and one Cu(4) atom.