The crystal 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 9-coordinate geometry to one Si(1), two equivalent Si(10), three equivalent Si(11), and three equivalent Si(3) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(2), two equivalent Si(4), two equivalent Si(5), and three equivalent Si(12) atoms. In the third Mg site, Mg(3) is bonded in a 8-coordinate geometry to one Si(11), two equivalent Si(2), two equivalent Si(3), and three equivalent Si(1) atoms. In the fourth Mg site, Mg(4) is bonded in a 8-coordinate geometry to one Si(12), two equivalent Si(1), two equivalent Si(4), and three equivalent Si(2) atoms. In the fifth Mg site, Mg(5) is bonded in a 8-coordinate geometry to one Si(4), two equivalent Si(12), two equivalent Si(9), and three equivalent Si(5) atoms. In the sixth Mg site, Mg(6) is bonded in a 8-coordinate geometry to one Si(11), one Si(8), three equivalent Si(10), and three equivalent Si(6) atoms. In the seventh Mg site, Mg(7) is bonded in a 7-coordinate geometry to one Si(9), two equivalent Si(5), two equivalent Si(8), and three equivalent Si(7) atoms. In the eighth Mg site, Mg(8) is bonded in a 7-coordinate geometry to two equivalent Si(6), two equivalent Si(7), and three equivalent Si(8) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(1), two equivalent Mg(4), three equivalent Mg(3), one Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(2), two equivalent Mg(3), three equivalent Mg(4), one Si(1), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a distorted q6 geometry to two equivalent Mg(3), three equivalent Mg(1), two equivalent Si(1), and two equivalent Si(11) atoms. In the fourth Si site, Si(4) is bonded in a distorted q6 geometry to one Mg(5), two equivalent Mg(2), two equivalent Mg(4), two equivalent Si(12), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 11-coordinate geometry to two equivalent Mg(2), two equivalent Mg(7), three 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 8-coordinate geometry to two equivalent Mg(8), three equivalent Mg(6), one Si(8), and two equivalent Si(10) atoms. In the seventh Si site, Si(7) is bonded in a 9-coordinate geometry to two equivalent Mg(8), three equivalent Mg(7), one Si(5), one Si(8), and two equivalent Si(9) atoms. In the eighth Si site, Si(8) is bonded in a 8-coordinate geometry to one Mg(6), two equivalent Mg(7), three equivalent Mg(8), one Si(6), and one Si(7) atom. In the ninth Si site, Si(9) is bonded in a 6-coordinate geometry to one Mg(7), two equivalent Mg(5), two equivalent Si(5), and two equivalent Si(7) atoms. In the tenth Si site, Si(10) is bonded in a 8-coordinate geometry to two equivalent Mg(1), three equivalent Mg(6), one Si(11), and two equivalent Si(6) atoms. In the eleventh Si site, Si(11) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(6), three equivalent Mg(1), one Si(10), and two equivalent Si(3) atoms. In the twelfth Si site, Si(12) is bonded in a 9-coordinate geometry to one Mg(4), two equivalent Mg(5), three equivalent Mg(2), 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   3.841
_cell_length_b   5.254
_cell_length_c   19.558
_cell_angle_alpha   93.139
_cell_angle_beta   94.693
_cell_angle_gamma   110.971
_symmetry_Int_Tables_number   1
_cell_volume   365.778
_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  0.525  0.032  0.174  1.0
  Mg  Mg1  1  0.335  0.006  0.803  1.0
  Mg  Mg2  1  0.833  0.758  0.046  1.0
  Mg  Mg3  1  0.053  0.307  0.943  1.0
  Mg  Mg4  1  0.576  0.575  0.717  1.0
  Mg  Mg5  1  0.774  0.379  0.320  1.0
  Mg  Mg6  1  0.352  0.319  0.566  1.0
  Mg  Mg7  1  0.998  0.698  0.465  1.0
  Si  Si8  1  0.547  0.193  0.044  1.0
  Si  Si9  1  0.340  0.877  0.942  1.0
  Si  Si10  1  0.203  0.432  0.120  1.0
  Si  Si11  1  0.693  0.656  0.873  1.0
  Si  Si12  1  0.869  0.152  0.683  1.0
  Si  Si13  1  0.512  0.812  0.360  1.0
  Si  Si14  1  0.619  0.874  0.560  1.0
  Si  Si15  1  0.722  0.142  0.461  1.0
  Si  Si16  1  0.135  0.811  0.635  1.0
  Si  Si17  1  0.049  0.951  0.290  1.0
  Si  Si18  1  0.823  0.608  0.192  1.0
  Si  Si19  1  0.041  0.418  0.805  1.0
[/CIF]
.
The crystal 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 9-coordinate geometry to one Si(1), two equivalent Si(10), three equivalent Si(11), and three equivalent Si(3) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(2), two equivalent Si(4), two equivalent Si(5), and three equivalent Si(12) atoms. In the third Mg site, Mg(3) is bonded in a 8-coordinate geometry to one Si(11), two equivalent Si(2), two equivalent Si(3), and three equivalent Si(1) atoms. In the fourth Mg site, Mg(4) is bonded in a 8-coordinate geometry to one Si(12), two equivalent Si(1), two equivalent Si(4), and three equivalent Si(2) atoms. In the fifth Mg site, Mg(5) is bonded in a 8-coordinate geometry to one Si(4), two equivalent Si(12), two equivalent Si(9), and three equivalent Si(5) atoms. In the sixth Mg site, Mg(6) is bonded in a 8-coordinate geometry to one Si(11), one Si(8), three equivalent Si(10), and three equivalent Si(6) atoms. In the seventh Mg site, Mg(7) is bonded in a 7-coordinate geometry to one Si(9), two equivalent Si(5), two equivalent Si(8), and three equivalent Si(7) atoms. In the eighth Mg site, Mg(8) is bonded in a 7-coordinate geometry to two equivalent Si(6), two equivalent Si(7), and three equivalent Si(8) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(1), two equivalent Mg(4), three equivalent Mg(3), one Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(2), two equivalent Mg(3), three equivalent Mg(4), one Si(1), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a distorted q6 geometry to two equivalent Mg(3), three equivalent Mg(1), two equivalent Si(1), and two equivalent Si(11) atoms. In the fourth Si site, Si(4) is bonded in a distorted q6 geometry to one Mg(5), two equivalent Mg(2), two equivalent Mg(4), two equivalent Si(12), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 11-coordinate geometry to two equivalent Mg(2), two equivalent Mg(7), three 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 8-coordinate geometry to two equivalent Mg(8), three equivalent Mg(6), one Si(8), and two equivalent Si(10) atoms. In the seventh Si site, Si(7) is bonded in a 9-coordinate geometry to two equivalent Mg(8), three equivalent Mg(7), one Si(5), one Si(8), and two equivalent Si(9) atoms. In the eighth Si site, Si(8) is bonded in a 8-coordinate geometry to one Mg(6), two equivalent Mg(7), three equivalent Mg(8), one Si(6), and one Si(7) atom. In the ninth Si site, Si(9) is bonded in a 6-coordinate geometry to one Mg(7), two equivalent Mg(5), two equivalent Si(5), and two equivalent Si(7) atoms. In the tenth Si site, Si(10) is bonded in a 8-coordinate geometry to two equivalent Mg(1), three equivalent Mg(6), one Si(11), and two equivalent Si(6) atoms. In the eleventh Si site, Si(11) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(6), three equivalent Mg(1), one Si(10), and two equivalent Si(3) atoms. In the twelfth Si site, Si(12) is bonded in a 9-coordinate geometry to one Mg(4), two equivalent Mg(5), three equivalent Mg(2), 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   3.841
_cell_length_b   5.254
_cell_length_c   19.558
_cell_angle_alpha   93.139
_cell_angle_beta   94.693
_cell_angle_gamma   110.971
_symmetry_Int_Tables_number   1
_cell_volume   365.778
_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  0.525  0.032  0.174  1.0
  Mg  Mg1  1  0.335  0.006  0.803  1.0
  Mg  Mg2  1  0.833  0.758  0.046  1.0
  Mg  Mg3  1  0.053  0.307  0.943  1.0
  Mg  Mg4  1  0.576  0.575  0.717  1.0
  Mg  Mg5  1  0.774  0.379  0.320  1.0
  Mg  Mg6  1  0.352  0.319  0.566  1.0
  Mg  Mg7  1  0.998  0.698  0.465  1.0
  Si  Si8  1  0.547  0.193  0.044  1.0
  Si  Si9  1  0.340  0.877  0.942  1.0
  Si  Si10  1  0.203  0.432  0.120  1.0
  Si  Si11  1  0.693  0.656  0.873  1.0
  Si  Si12  1  0.869  0.152  0.683  1.0
  Si  Si13  1  0.512  0.812  0.360  1.0
  Si  Si14  1  0.619  0.874  0.560  1.0
  Si  Si15  1  0.722  0.142  0.461  1.0
  Si  Si16  1  0.135  0.811  0.635  1.0
  Si  Si17  1  0.049  0.951  0.290  1.0
  Si  Si18  1  0.823  0.608  0.192  1.0
  Si  Si19  1  0.041  0.418  0.805  1.0
[/CIF]
.