The crystal structure described by Na4Mg(SiSe3)2 crystallizes in the monoclinic C2 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form NaSe6 octahedra that share corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with two equivalent Na(4)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, edges with two equivalent Na(4)Se6 octahedra, and edges with three equivalent Mg(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 6-13°. In the second Na site, Na(2) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Mg(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Mg(1)Se6 octahedra, edges with three equivalent Na(3)Se6 octahedra, and edges with three equivalent Na(4)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-13°. In the third Na site, Na(3) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Mg(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Mg(1)Se6 octahedra, edges with three equivalent Na(2)Se6 octahedra, and edges with three equivalent Na(4)Se6 octahedra. The corner-sharing octahedral tilt angles are 6°. In the fourth Na site, Na(4) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Mg(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Mg(1)Se6 octahedra, edges with three equivalent Na(2)Se6 octahedra, and edges with three equivalent Na(3)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-8°. Mg(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form MgSe6 octahedra that share corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with two equivalent Na(4)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, edges with two equivalent Na(4)Se6 octahedra, and edges with three equivalent Na(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 6-8°. Si(1) is bonded in a distorted trigonal non-coplanar geometry to one Se(1), one Se(2), and one Se(3) atom. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Mg(1), and one Si(1) atom to form a mixture of edge and corner-sharing SeNa4MgSi octahedra. The corner-sharing octahedral tilt angles range from 3-89°. In the second Se site, Se(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Mg(1), and one Si(1) atom to form a mixture of edge and corner-sharing SeNa4MgSi octahedra. The corner-sharing octahedral tilt angles range from 3-89°. In the third Se site, Se(3) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Mg(1), and one Si(1) atom to form a mixture of edge and corner-sharing SeNa4MgSi octahedra. The corner-sharing octahedral tilt angles range from 3-88°. is represented by the CIF card [CIF]
data_Na4Mg(SiSe3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.047
_cell_length_b   7.047
_cell_length_c   7.035
_cell_angle_alpha   81.017
_cell_angle_beta   81.017
_cell_angle_gamma   114.235
_symmetry_Int_Tables_number   1
_cell_volume   305.066
_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
  Na  Na0  1  0.512  0.488  0.500  1.0
  Na  Na1  1  0.359  0.641  0.000  1.0
  Na  Na2  1  0.682  0.318  0.000  1.0
  Na  Na3  1  0.047  0.953  0.000  1.0
  Mg  Mg4  1  0.872  0.128  0.500  1.0
  Si  Si5  1  0.355  0.961  0.445  1.0
  Si  Si6  1  0.039  0.645  0.555  1.0
  Se  Se7  1  0.262  0.198  0.269  1.0
  Se  Se8  1  0.802  0.738  0.731  1.0
  Se  Se9  1  0.471  0.058  0.716  1.0
  Se  Se10  1  0.942  0.529  0.284  1.0
  Se  Se11  1  0.619  0.918  0.254  1.0
  Se  Se12  1  0.082  0.381  0.746  1.0
[/CIF]
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The crystal structure described by Na4Mg(SiSe3)2 crystallizes in the monoclinic C2 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form NaSe6 octahedra that share corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with two equivalent Na(4)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, edges with two equivalent Na(4)Se6 octahedra, and edges with three equivalent Mg(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 6-13°. In the second Na site, Na(2) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Mg(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Mg(1)Se6 octahedra, edges with three equivalent Na(3)Se6 octahedra, and edges with three equivalent Na(4)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-13°. In the third Na site, Na(3) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Mg(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Mg(1)Se6 octahedra, edges with three equivalent Na(2)Se6 octahedra, and edges with three equivalent Na(4)Se6 octahedra. The corner-sharing octahedral tilt angles are 6°. In the fourth Na site, Na(4) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Mg(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Mg(1)Se6 octahedra, edges with three equivalent Na(2)Se6 octahedra, and edges with three equivalent Na(3)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-8°. Mg(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form MgSe6 octahedra that share corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with two equivalent Na(4)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, edges with two equivalent Na(4)Se6 octahedra, and edges with three equivalent Na(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 6-8°. Si(1) is bonded in a distorted trigonal non-coplanar geometry to one Se(1), one Se(2), and one Se(3) atom. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Mg(1), and one Si(1) atom to form a mixture of edge and corner-sharing SeNa4MgSi octahedra. The corner-sharing octahedral tilt angles range from 3-89°. In the second Se site, Se(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Mg(1), and one Si(1) atom to form a mixture of edge and corner-sharing SeNa4MgSi octahedra. The corner-sharing octahedral tilt angles range from 3-89°. In the third Se site, Se(3) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Mg(1), and one Si(1) atom to form a mixture of edge and corner-sharing SeNa4MgSi octahedra. The corner-sharing octahedral tilt angles range from 3-88°. is represented by the CIF card [CIF]
data_Na4Mg(SiSe3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.047
_cell_length_b   7.047
_cell_length_c   7.035
_cell_angle_alpha   81.017
_cell_angle_beta   81.017
_cell_angle_gamma   114.235
_symmetry_Int_Tables_number   1
_cell_volume   305.066
_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
  Na  Na0  1  0.512  0.488  0.500  1.0
  Na  Na1  1  0.359  0.641  0.000  1.0
  Na  Na2  1  0.682  0.318  0.000  1.0
  Na  Na3  1  0.047  0.953  0.000  1.0
  Mg  Mg4  1  0.872  0.128  0.500  1.0
  Si  Si5  1  0.355  0.961  0.445  1.0
  Si  Si6  1  0.039  0.645  0.555  1.0
  Se  Se7  1  0.262  0.198  0.269  1.0
  Se  Se8  1  0.802  0.738  0.731  1.0
  Se  Se9  1  0.471  0.058  0.716  1.0
  Se  Se10  1  0.942  0.529  0.284  1.0
  Se  Se11  1  0.619  0.918  0.254  1.0
  Se  Se12  1  0.082  0.381  0.746  1.0
[/CIF]
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