The structure described by Mg2Si3 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to one Si(1), one Si(10), two equivalent Si(11), 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 one Si(2), one Si(9), two equivalent Si(12), and two equivalent Si(4) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(1), one Si(3), two equivalent Si(11), 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(4), two equivalent Si(1), and two equivalent Si(12) atoms. In the fifth Mg site, Mg(5) is bonded in a 5-coordinate geometry to one Si(4), two equivalent Si(12), two equivalent Si(5), and two equivalent Si(9) atoms. In the sixth Mg site, Mg(6) is bonded in a 8-coordinate geometry to one Si(3), one Si(8), two equivalent Si(10), two equivalent Si(11), and two equivalent Si(6) atoms. In the seventh Mg site, Mg(7) is bonded in a 6-coordinate geometry to two equivalent Si(7), two equivalent Si(8), and two equivalent Si(9) atoms. In the eighth Mg site, Mg(8) is bonded in a 5-coordinate geometry to one Si(10), one Si(8), two equivalent Si(6), and two equivalent Si(7) atoms. There are twelve 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(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), 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 8-coordinate geometry to one Mg(3), one Mg(6), two equivalent Mg(1), two equivalent Si(1), and two equivalent Si(11) atoms. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one Mg(4), one Mg(5), two equivalent Mg(2), two equivalent Si(12), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 6-coordinate geometry to two equivalent Mg(5), one Si(12), one Si(7), and two equivalent Si(9) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(6), two equivalent Mg(8), one Si(11), and two equivalent Si(10) atoms. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to two equivalent Mg(7), two equivalent Mg(8), one Si(5), and one Si(8) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(6), one Mg(8), two equivalent Mg(7), one Si(7), and two equivalent Si(10) atoms. In the ninth Si site, Si(9) is bonded in a 7-coordinate geometry to one Mg(2), two equivalent Mg(5), two equivalent Mg(7), and two equivalent Si(5) atoms. In the tenth Si site, Si(10) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(8), two equivalent Mg(6), two equivalent Si(6), and two equivalent Si(8) atoms. In the eleventh Si site, Si(11) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(6), one Si(6), and two equivalent Si(3) atoms. In the twelfth Si site, Si(12) is bonded in a 9-coordinate geometry to two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), one Si(5), and two equivalent Si(4) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.552
_cell_length_b   6.069
_cell_length_c   17.980
_cell_angle_alpha   94.849
_cell_angle_beta   94.400
_cell_angle_gamma   106.999
_symmetry_Int_Tables_number   1
_cell_volume   367.287
_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  0.725  0.137  0.202  1.0
  Mg  Mg1  1  0.827  0.738  0.805  1.0
  Mg  Mg2  1  0.467  0.816  0.055  1.0
  Mg  Mg3  1  0.087  0.068  0.947  1.0
  Mg  Mg4  1  0.069  0.345  0.697  1.0
  Mg  Mg5  1  0.463  0.538  0.298  1.0
  Mg  Mg6  1  0.093  0.562  0.546  1.0
  Mg  Mg7  1  0.736  0.875  0.454  1.0
  Si  Si8  1  0.736  0.304  0.052  1.0
  Si  Si9  1  0.802  0.567  0.950  1.0
  Si  Si10  1  0.348  0.448  0.142  1.0
  Si  Si11  1  0.196  0.423  0.857  1.0
  Si  Si12  1  0.350  0.962  0.678  1.0
  Si  Si13  1  0.169  0.918  0.316  1.0
  Si  Si14  1  0.403  0.137  0.554  1.0
  Si  Si15  1  0.453  0.373  0.441  1.0
  Si  Si16  1  0.707  0.693  0.657  1.0
  Si  Si17  1  0.833  0.218  0.355  1.0
  Si  Si18  1  0.012  0.750  0.182  1.0
  Si  Si19  1  0.524  0.131  0.813  1.0
[/CIF]
.
The structure described by Mg2Si3 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to one Si(1), one Si(10), two equivalent Si(11), 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 one Si(2), one Si(9), two equivalent Si(12), and two equivalent Si(4) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(1), one Si(3), two equivalent Si(11), 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(4), two equivalent Si(1), and two equivalent Si(12) atoms. In the fifth Mg site, Mg(5) is bonded in a 5-coordinate geometry to one Si(4), two equivalent Si(12), two equivalent Si(5), and two equivalent Si(9) atoms. In the sixth Mg site, Mg(6) is bonded in a 8-coordinate geometry to one Si(3), one Si(8), two equivalent Si(10), two equivalent Si(11), and two equivalent Si(6) atoms. In the seventh Mg site, Mg(7) is bonded in a 6-coordinate geometry to two equivalent Si(7), two equivalent Si(8), and two equivalent Si(9) atoms. In the eighth Mg site, Mg(8) is bonded in a 5-coordinate geometry to one Si(10), one Si(8), two equivalent Si(6), and two equivalent Si(7) atoms. There are twelve 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(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), 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 8-coordinate geometry to one Mg(3), one Mg(6), two equivalent Mg(1), two equivalent Si(1), and two equivalent Si(11) atoms. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one Mg(4), one Mg(5), two equivalent Mg(2), two equivalent Si(12), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 6-coordinate geometry to two equivalent Mg(5), one Si(12), one Si(7), and two equivalent Si(9) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(6), two equivalent Mg(8), one Si(11), and two equivalent Si(10) atoms. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to two equivalent Mg(7), two equivalent Mg(8), one Si(5), and one Si(8) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(6), one Mg(8), two equivalent Mg(7), one Si(7), and two equivalent Si(10) atoms. In the ninth Si site, Si(9) is bonded in a 7-coordinate geometry to one Mg(2), two equivalent Mg(5), two equivalent Mg(7), and two equivalent Si(5) atoms. In the tenth Si site, Si(10) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(8), two equivalent Mg(6), two equivalent Si(6), and two equivalent Si(8) atoms. In the eleventh Si site, Si(11) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(6), one Si(6), and two equivalent Si(3) atoms. In the twelfth Si site, Si(12) is bonded in a 9-coordinate geometry to two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), one Si(5), and two equivalent Si(4) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.552
_cell_length_b   6.069
_cell_length_c   17.980
_cell_angle_alpha   94.849
_cell_angle_beta   94.400
_cell_angle_gamma   106.999
_symmetry_Int_Tables_number   1
_cell_volume   367.287
_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  0.725  0.137  0.202  1.0
  Mg  Mg1  1  0.827  0.738  0.805  1.0
  Mg  Mg2  1  0.467  0.816  0.055  1.0
  Mg  Mg3  1  0.087  0.068  0.947  1.0
  Mg  Mg4  1  0.069  0.345  0.697  1.0
  Mg  Mg5  1  0.463  0.538  0.298  1.0
  Mg  Mg6  1  0.093  0.562  0.546  1.0
  Mg  Mg7  1  0.736  0.875  0.454  1.0
  Si  Si8  1  0.736  0.304  0.052  1.0
  Si  Si9  1  0.802  0.567  0.950  1.0
  Si  Si10  1  0.348  0.448  0.142  1.0
  Si  Si11  1  0.196  0.423  0.857  1.0
  Si  Si12  1  0.350  0.962  0.678  1.0
  Si  Si13  1  0.169  0.918  0.316  1.0
  Si  Si14  1  0.403  0.137  0.554  1.0
  Si  Si15  1  0.453  0.373  0.441  1.0
  Si  Si16  1  0.707  0.693  0.657  1.0
  Si  Si17  1  0.833  0.218  0.355  1.0
  Si  Si18  1  0.012  0.750  0.182  1.0
  Si  Si19  1  0.524  0.131  0.813  1.0
[/CIF]
.