The crystal structure described by Mg2Si3 crystallizes in the monoclinic C2/m space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to one Si(1), three equivalent Si(3), and four equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to one Si(4), three equivalent Si(2), and four equivalent Si(5) atoms. In the third Mg site, Mg(3) is bonded to one Si(1), one Si(2), one Si(3), and two equivalent Si(6) atoms to form distorted corner-sharing MgSi5 trigonal bipyramids. In the fourth Mg site, Mg(4) is bonded in a 7-coordinate geometry to one Si(3), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(5) atoms. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(4), one Si(4), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(3), two equivalent Mg(4), three equivalent Mg(2), one Si(5), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(4), three equivalent Mg(1), one Si(6), and two equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 5-coordinate geometry to one Mg(2), one Si(1), one Si(5), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent Mg(4), four equivalent Mg(2), one Si(2), one Si(4), and one Si(5) atom. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to two equivalent Mg(3), four equivalent Mg(1), one Si(3), and one Si(6) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.071
_cell_length_b   6.071
_cell_length_c   15.706
_cell_angle_alpha   82.268
_cell_angle_beta   82.268
_cell_angle_gamma   40.134
_symmetry_Int_Tables_number   1
_cell_volume   369.330
_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  0.138  0.138  0.508  1.0
  Mg  Mg1  1  0.362  0.362  1.000  1.0
  Mg  Mg2  1  0.896  0.896  0.689  1.0
  Mg  Mg3  1  0.520  0.520  0.801  1.0
  Mg  Mg4  1  0.638  0.638  0.000  1.0
  Mg  Mg5  1  0.862  0.862  0.492  1.0
  Mg  Mg6  1  0.480  0.480  0.199  1.0
  Mg  Mg7  1  0.104  0.104  0.311  1.0
  Si  Si8  1  0.149  0.149  0.708  1.0
  Si  Si9  1  0.834  0.834  0.868  1.0
  Si  Si10  1  0.678  0.678  0.625  1.0
  Si  Si11  1  0.232  0.232  0.839  1.0
  Si  Si12  1  0.980  0.980  0.078  1.0
  Si  Si13  1  0.521  0.521  0.420  1.0
  Si  Si14  1  0.768  0.768  0.161  1.0
  Si  Si15  1  0.851  0.851  0.292  1.0
  Si  Si16  1  0.166  0.166  0.132  1.0
  Si  Si17  1  0.322  0.322  0.375  1.0
  Si  Si18  1  0.479  0.479  0.580  1.0
  Si  Si19  1  0.020  0.020  0.922  1.0
[/CIF]
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The crystal structure described by Mg2Si3 crystallizes in the monoclinic C2/m space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to one Si(1), three equivalent Si(3), and four equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to one Si(4), three equivalent Si(2), and four equivalent Si(5) atoms. In the third Mg site, Mg(3) is bonded to one Si(1), one Si(2), one Si(3), and two equivalent Si(6) atoms to form distorted corner-sharing MgSi5 trigonal bipyramids. In the fourth Mg site, Mg(4) is bonded in a 7-coordinate geometry to one Si(3), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(5) atoms. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(4), one Si(4), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(3), two equivalent Mg(4), three equivalent Mg(2), one Si(5), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(4), three equivalent Mg(1), one Si(6), and two equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 5-coordinate geometry to one Mg(2), one Si(1), one Si(5), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent Mg(4), four equivalent Mg(2), one Si(2), one Si(4), and one Si(5) atom. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to two equivalent Mg(3), four equivalent Mg(1), one Si(3), and one Si(6) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.071
_cell_length_b   6.071
_cell_length_c   15.706
_cell_angle_alpha   82.268
_cell_angle_beta   82.268
_cell_angle_gamma   40.134
_symmetry_Int_Tables_number   1
_cell_volume   369.330
_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  0.138  0.138  0.508  1.0
  Mg  Mg1  1  0.362  0.362  1.000  1.0
  Mg  Mg2  1  0.896  0.896  0.689  1.0
  Mg  Mg3  1  0.520  0.520  0.801  1.0
  Mg  Mg4  1  0.638  0.638  0.000  1.0
  Mg  Mg5  1  0.862  0.862  0.492  1.0
  Mg  Mg6  1  0.480  0.480  0.199  1.0
  Mg  Mg7  1  0.104  0.104  0.311  1.0
  Si  Si8  1  0.149  0.149  0.708  1.0
  Si  Si9  1  0.834  0.834  0.868  1.0
  Si  Si10  1  0.678  0.678  0.625  1.0
  Si  Si11  1  0.232  0.232  0.839  1.0
  Si  Si12  1  0.980  0.980  0.078  1.0
  Si  Si13  1  0.521  0.521  0.420  1.0
  Si  Si14  1  0.768  0.768  0.161  1.0
  Si  Si15  1  0.851  0.851  0.292  1.0
  Si  Si16  1  0.166  0.166  0.132  1.0
  Si  Si17  1  0.322  0.322  0.375  1.0
  Si  Si18  1  0.479  0.479  0.580  1.0
  Si  Si19  1  0.020  0.020  0.922  1.0
[/CIF]
.