The compound described by Mg2Si crystallizes in the monoclinic P2_1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Si(2) and two equivalent Si(1) atoms. In the second Mg site, Mg(2) is bonded in a 3-coordinate geometry to two equivalent Si(1) and two equivalent Si(2) atoms. In the third Mg site, Mg(3) is bonded to two equivalent Si(1) and two equivalent Si(2) atoms to form distorted corner-sharing MgSi4 tetrahedra. In the fourth Mg site, Mg(4) is bonded in a 4-coordinate geometry to two equivalent Si(1) and two equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and one Si(2) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and one Si(1) atom. is represented by the CIF card [CIF]
data_Mg2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.757
_cell_length_b   6.187
_cell_length_c   7.213
_cell_angle_alpha   74.109
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   247.111
_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  0.883  0.390  0.053  1.0
  Mg  Mg1  1  0.300  0.318  0.374  1.0
  Mg  Mg2  1  0.302  0.758  0.498  1.0
  Mg  Mg3  1  0.407  0.053  0.088  1.0
  Mg  Mg4  1  0.802  0.242  0.502  1.0
  Mg  Mg5  1  0.907  0.947  0.912  1.0
  Mg  Mg6  1  0.383  0.610  0.947  1.0
  Mg  Mg7  1  0.800  0.682  0.626  1.0
  Si  Si8  1  0.160  0.343  0.735  1.0
  Si  Si9  1  0.660  0.657  0.265  1.0
  Si  Si10  1  0.945  0.966  0.280  1.0
  Si  Si11  1  0.445  0.034  0.720  1.0
[/CIF]
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The compound described by Mg2Si crystallizes in the monoclinic P2_1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Si(2) and two equivalent Si(1) atoms. In the second Mg site, Mg(2) is bonded in a 3-coordinate geometry to two equivalent Si(1) and two equivalent Si(2) atoms. In the third Mg site, Mg(3) is bonded to two equivalent Si(1) and two equivalent Si(2) atoms to form distorted corner-sharing MgSi4 tetrahedra. In the fourth Mg site, Mg(4) is bonded in a 4-coordinate geometry to two equivalent Si(1) and two equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and one Si(2) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and one Si(1) atom. is represented by the CIF card [CIF]
data_Mg2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.757
_cell_length_b   6.187
_cell_length_c   7.213
_cell_angle_alpha   74.109
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   247.111
_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  0.883  0.390  0.053  1.0
  Mg  Mg1  1  0.300  0.318  0.374  1.0
  Mg  Mg2  1  0.302  0.758  0.498  1.0
  Mg  Mg3  1  0.407  0.053  0.088  1.0
  Mg  Mg4  1  0.802  0.242  0.502  1.0
  Mg  Mg5  1  0.907  0.947  0.912  1.0
  Mg  Mg6  1  0.383  0.610  0.947  1.0
  Mg  Mg7  1  0.800  0.682  0.626  1.0
  Si  Si8  1  0.160  0.343  0.735  1.0
  Si  Si9  1  0.660  0.657  0.265  1.0
  Si  Si10  1  0.945  0.966  0.280  1.0
  Si  Si11  1  0.445  0.034  0.720  1.0
[/CIF]
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