The crystal structure described by Mg2Si3 is Magnesium tetraboride-like structured and 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 6-coordinate geometry to one Si(1), one Si(5), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 3-coordinate geometry to one Si(6) and five equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a 8-coordinate geometry to one Si(2), one Si(4), two equivalent Si(3), two equivalent Si(5), and two equivalent Si(6) atoms. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one Si(5), two equivalent Si(3), and three equivalent Si(4) atoms. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(1), five equivalent Mg(2), one Si(1), and two equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(3), two equivalent Mg(1), two equivalent Si(1), and two equivalent Si(6) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(4), one Si(6), and two equivalent Si(5) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(3), three equivalent Mg(4), one Si(4), and two equivalent Si(5) atoms. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(4), two equivalent Mg(3), two equivalent Si(3), and two equivalent Si(4) atoms. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), one Si(3), and two equivalent Si(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.993
_cell_length_b   5.993
_cell_length_c   17.814
_cell_angle_alpha   88.246
_cell_angle_beta   88.246
_cell_angle_gamma   34.768
_symmetry_Int_Tables_number   1
_cell_volume   364.633
_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  0.979  0.979  0.802  1.0
  Mg  Mg1  1  0.021  0.021  0.198  1.0
  Mg  Mg2  1  0.341  0.341  0.948  1.0
  Mg  Mg3  1  0.659  0.659  0.052  1.0
  Mg  Mg4  1  0.330  0.330  0.296  1.0
  Mg  Mg5  1  0.670  0.670  0.704  1.0
  Mg  Mg6  1  0.182  0.182  0.445  1.0
  Mg  Mg7  1  0.818  0.818  0.555  1.0
  Si  Si8  1  0.073  0.073  0.948  1.0
  Si  Si9  1  0.927  0.927  0.052  1.0
  Si  Si10  1  0.653  0.653  0.859  1.0
  Si  Si11  1  0.347  0.347  0.141  1.0
  Si  Si12  1  0.634  0.634  0.323  1.0
  Si  Si13  1  0.366  0.366  0.677  1.0
  Si  Si14  1  0.427  0.427  0.450  1.0
  Si  Si15  1  0.573  0.573  0.550  1.0
  Si  Si16  1  0.986  0.986  0.358  1.0
  Si  Si17  1  0.014  0.014  0.642  1.0
  Si  Si18  1  0.284  0.284  0.805  1.0
  Si  Si19  1  0.716  0.716  0.195  1.0
[/CIF]
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The crystal structure described by Mg2Si3 is Magnesium tetraboride-like structured and 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 6-coordinate geometry to one Si(1), one Si(5), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 3-coordinate geometry to one Si(6) and five equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a 8-coordinate geometry to one Si(2), one Si(4), two equivalent Si(3), two equivalent Si(5), and two equivalent Si(6) atoms. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one Si(5), two equivalent Si(3), and three equivalent Si(4) atoms. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(1), five equivalent Mg(2), one Si(1), and two equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(3), two equivalent Mg(1), two equivalent Si(1), and two equivalent Si(6) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(4), one Si(6), and two equivalent Si(5) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(3), three equivalent Mg(4), one Si(4), and two equivalent Si(5) atoms. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(4), two equivalent Mg(3), two equivalent Si(3), and two equivalent Si(4) atoms. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), one Si(3), and two equivalent Si(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.993
_cell_length_b   5.993
_cell_length_c   17.814
_cell_angle_alpha   88.246
_cell_angle_beta   88.246
_cell_angle_gamma   34.768
_symmetry_Int_Tables_number   1
_cell_volume   364.633
_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  0.979  0.979  0.802  1.0
  Mg  Mg1  1  0.021  0.021  0.198  1.0
  Mg  Mg2  1  0.341  0.341  0.948  1.0
  Mg  Mg3  1  0.659  0.659  0.052  1.0
  Mg  Mg4  1  0.330  0.330  0.296  1.0
  Mg  Mg5  1  0.670  0.670  0.704  1.0
  Mg  Mg6  1  0.182  0.182  0.445  1.0
  Mg  Mg7  1  0.818  0.818  0.555  1.0
  Si  Si8  1  0.073  0.073  0.948  1.0
  Si  Si9  1  0.927  0.927  0.052  1.0
  Si  Si10  1  0.653  0.653  0.859  1.0
  Si  Si11  1  0.347  0.347  0.141  1.0
  Si  Si12  1  0.634  0.634  0.323  1.0
  Si  Si13  1  0.366  0.366  0.677  1.0
  Si  Si14  1  0.427  0.427  0.450  1.0
  Si  Si15  1  0.573  0.573  0.550  1.0
  Si  Si16  1  0.986  0.986  0.358  1.0
  Si  Si17  1  0.014  0.014  0.642  1.0
  Si  Si18  1  0.284  0.284  0.805  1.0
  Si  Si19  1  0.716  0.716  0.195  1.0
[/CIF]
.