The material structure described by Mg5Se crystallizes in the monoclinic Cm space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted L-shaped geometry to two equivalent Mg(3), three equivalent Mg(2), and two equivalent Se(1) atoms. In the second Mg site, Mg(2) is bonded in a 11-coordinate geometry to one Mg(5), two equivalent Mg(2), two equivalent Mg(4), three equivalent Mg(1), and three equivalent Mg(3) atoms. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(5), three equivalent Mg(2), and three equivalent Mg(4) atoms to form a mixture of corner, face, and edge-sharing MgMg12 cuboctahedra. In the fourth Mg site, Mg(4) is bonded in a distorted L-shaped geometry to two equivalent Mg(2), three equivalent Mg(3), and two equivalent Se(1) atoms. In the fifth Mg site, Mg(5) is bonded in a 2-coordinate geometry to one Mg(2), two equivalent Mg(3), and two equivalent Se(1) atoms. Se(1) is bonded in a 6-coordinate geometry to two equivalent Mg(1), two equivalent Mg(4), and two equivalent Mg(5) atoms. is represented by the CIF card [CIF]
data_Mg5Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.687
_cell_length_b   5.687
_cell_length_c   7.921
_cell_angle_alpha   73.282
_cell_angle_beta   73.282
_cell_angle_gamma   35.220
_symmetry_Int_Tables_number   1
_cell_volume   140.849
_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  0.024  0.024  0.061  1.0
  Mg  Mg1  1  0.340  0.340  0.895  1.0
  Mg  Mg2  1  0.657  0.657  0.708  1.0
  Mg  Mg3  1  0.950  0.950  0.546  1.0
  Mg  Mg4  1  0.280  0.280  0.327  1.0
  Se  Se5  1  0.583  0.583  0.296  1.0
[/CIF]
.
The material structure described by Mg5Se crystallizes in the monoclinic Cm space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted L-shaped geometry to two equivalent Mg(3), three equivalent Mg(2), and two equivalent Se(1) atoms. In the second Mg site, Mg(2) is bonded in a 11-coordinate geometry to one Mg(5), two equivalent Mg(2), two equivalent Mg(4), three equivalent Mg(1), and three equivalent Mg(3) atoms. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(5), three equivalent Mg(2), and three equivalent Mg(4) atoms to form a mixture of corner, face, and edge-sharing MgMg12 cuboctahedra. In the fourth Mg site, Mg(4) is bonded in a distorted L-shaped geometry to two equivalent Mg(2), three equivalent Mg(3), and two equivalent Se(1) atoms. In the fifth Mg site, Mg(5) is bonded in a 2-coordinate geometry to one Mg(2), two equivalent Mg(3), and two equivalent Se(1) atoms. Se(1) is bonded in a 6-coordinate geometry to two equivalent Mg(1), two equivalent Mg(4), and two equivalent Mg(5) atoms. is represented by the CIF card [CIF]
data_Mg5Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.687
_cell_length_b   5.687
_cell_length_c   7.921
_cell_angle_alpha   73.282
_cell_angle_beta   73.282
_cell_angle_gamma   35.220
_symmetry_Int_Tables_number   1
_cell_volume   140.849
_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  0.024  0.024  0.061  1.0
  Mg  Mg1  1  0.340  0.340  0.895  1.0
  Mg  Mg2  1  0.657  0.657  0.708  1.0
  Mg  Mg3  1  0.950  0.950  0.546  1.0
  Mg  Mg4  1  0.280  0.280  0.327  1.0
  Se  Se5  1  0.583  0.583  0.296  1.0
[/CIF]
.