The structure described by Mg2Si3 crystallizes in the triclinic P-1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to two equivalent Si(3) and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to three equivalent Si(4) and three equivalent Si(5) atoms. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Si(3), one Si(4), two equivalent Si(1), and two equivalent Si(2) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(2), one Si(3), one Si(5), and two equivalent Si(1) atoms. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to two equivalent Mg(3), two equivalent Mg(4), one Si(2), one Si(3), and one Si(6) atom. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to one Mg(4), two equivalent Mg(3), one Si(1), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(1), one Si(1), and two equivalent Si(6) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(3), three equivalent Mg(2), one Si(5), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 6-coordinate geometry to one Mg(4), three equivalent Mg(2), one Si(4), and one Si(5) atom. In the sixth Si site, Si(6) is bonded in a 2-coordinate geometry to two equivalent Mg(1), one Si(1), and two equivalent Si(3) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.079
_cell_length_b   6.221
_cell_length_c   16.454
_cell_angle_alpha   80.562
_cell_angle_beta   87.529
_cell_angle_gamma   78.908
_symmetry_Int_Tables_number   1
_cell_volume   404.176
_cell_formula_units_Z   4
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  0.819  0.267  0.957  1.0
  Mg  Mg1  1  0.042  0.731  0.527  1.0
  Mg  Mg2  1  0.392  0.306  0.798  1.0
  Mg  Mg3  1  0.652  0.758  0.722  1.0
  Mg  Mg4  1  0.958  0.269  0.473  1.0
  Mg  Mg5  1  0.181  0.733  0.043  1.0
  Mg  Mg6  1  0.348  0.242  0.278  1.0
  Mg  Mg7  1  0.608  0.694  0.202  1.0
  Si  Si8  1  0.054  0.999  0.778  1.0
  Si  Si9  1  0.865  0.350  0.680  1.0
  Si  Si10  1  0.350  0.644  0.883  1.0
  Si  Si11  1  0.374  0.343  0.604  1.0
  Si  Si12  1  0.550  0.018  0.427  1.0
  Si  Si13  1  0.224  0.140  0.097  1.0
  Si  Si14  1  0.135  0.650  0.320  1.0
  Si  Si15  1  0.946  0.001  0.222  1.0
  Si  Si16  1  0.626  0.657  0.396  1.0
  Si  Si17  1  0.650  0.356  0.117  1.0
  Si  Si18  1  0.776  0.860  0.903  1.0
  Si  Si19  1  0.450  0.982  0.573  1.0
[/CIF]
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The structure described by Mg2Si3 crystallizes in the triclinic P-1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to two equivalent Si(3) and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to three equivalent Si(4) and three equivalent Si(5) atoms. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Si(3), one Si(4), two equivalent Si(1), and two equivalent Si(2) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(2), one Si(3), one Si(5), and two equivalent Si(1) atoms. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to two equivalent Mg(3), two equivalent Mg(4), one Si(2), one Si(3), and one Si(6) atom. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to one Mg(4), two equivalent Mg(3), one Si(1), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(1), one Si(1), and two equivalent Si(6) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(3), three equivalent Mg(2), one Si(5), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 6-coordinate geometry to one Mg(4), three equivalent Mg(2), one Si(4), and one Si(5) atom. In the sixth Si site, Si(6) is bonded in a 2-coordinate geometry to two equivalent Mg(1), one Si(1), and two equivalent Si(3) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.079
_cell_length_b   6.221
_cell_length_c   16.454
_cell_angle_alpha   80.562
_cell_angle_beta   87.529
_cell_angle_gamma   78.908
_symmetry_Int_Tables_number   1
_cell_volume   404.176
_cell_formula_units_Z   4
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  0.819  0.267  0.957  1.0
  Mg  Mg1  1  0.042  0.731  0.527  1.0
  Mg  Mg2  1  0.392  0.306  0.798  1.0
  Mg  Mg3  1  0.652  0.758  0.722  1.0
  Mg  Mg4  1  0.958  0.269  0.473  1.0
  Mg  Mg5  1  0.181  0.733  0.043  1.0
  Mg  Mg6  1  0.348  0.242  0.278  1.0
  Mg  Mg7  1  0.608  0.694  0.202  1.0
  Si  Si8  1  0.054  0.999  0.778  1.0
  Si  Si9  1  0.865  0.350  0.680  1.0
  Si  Si10  1  0.350  0.644  0.883  1.0
  Si  Si11  1  0.374  0.343  0.604  1.0
  Si  Si12  1  0.550  0.018  0.427  1.0
  Si  Si13  1  0.224  0.140  0.097  1.0
  Si  Si14  1  0.135  0.650  0.320  1.0
  Si  Si15  1  0.946  0.001  0.222  1.0
  Si  Si16  1  0.626  0.657  0.396  1.0
  Si  Si17  1  0.650  0.356  0.117  1.0
  Si  Si18  1  0.776  0.860  0.903  1.0
  Si  Si19  1  0.450  0.982  0.573  1.0
[/CIF]
.