The compound described by Mg2Si3 crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to one Si(3), two equivalent Si(10), two equivalent Si(11), and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(12), one Si(4), two equivalent Si(5), and two equivalent Si(9) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(2), one Si(3), two equivalent Si(1), and two equivalent Si(11) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(4), and two equivalent Si(12) atoms. In the fifth Mg site, Mg(5) is bonded in a 5-coordinate geometry to one Si(9), two equivalent Si(12), and two equivalent Si(5) atoms. In the sixth Mg site, Mg(6) is bonded in a 7-coordinate geometry to one Si(10), two equivalent Si(11), two equivalent Si(3), and two equivalent Si(6) atoms. In the seventh Mg site, Mg(7) is bonded in a 6-coordinate geometry to one Si(8), one Si(9), two equivalent Si(5), and two equivalent Si(7) atoms. In the eighth Mg site, Mg(8) is bonded in a 6-coordinate geometry to one Si(10), one Si(7), two equivalent Si(6), and two equivalent Si(8) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to one Mg(4), two equivalent Mg(3), one Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to one Mg(3), one Mg(4), one Si(1), one Si(12), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(6), one Si(11), 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 Mg(4), one Si(12), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to two equivalent Mg(2), two equivalent Mg(5), two equivalent Mg(7), and one Si(9) atom. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(6), two equivalent Mg(8), one Si(10), and one Si(11) atom. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to one Mg(8), two equivalent Mg(7), one Si(8), and two equivalent Si(9) atoms. In the eighth Si site, Si(8) is bonded in a 6-coordinate geometry to one Mg(7), two equivalent Mg(8), 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(5), one Mg(7), two equivalent Mg(2), one Si(5), and two equivalent Si(7) atoms. In the tenth Si site, Si(10) is bonded in a 7-coordinate geometry to one Mg(6), one Mg(8), two equivalent Mg(1), one Si(6), and two equivalent Si(8) atoms. In the eleventh Si site, Si(11) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(6), one Si(3), and one Si(6) atom. In the twelfth Si site, Si(12) is bonded in a 7-coordinate geometry to one Mg(2), two equivalent Mg(4), two equivalent Mg(5), one Si(2), and one Si(4) atom. is represented by the CIF file [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.860
_cell_length_b   6.230
_cell_length_c   17.453
_cell_angle_alpha   82.579
_cell_angle_beta   86.598
_cell_angle_gamma   72.365
_symmetry_Int_Tables_number   1
_cell_volume   396.467
_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  0.206  0.009  0.247  1.0
  Mg  Mg1  1  0.092  0.906  0.749  1.0
  Mg  Mg2  1  0.292  0.948  0.070  1.0
  Mg  Mg3  1  0.879  0.231  0.911  1.0
  Mg  Mg4  1  0.804  0.447  0.735  1.0
  Mg  Mg5  1  0.480  0.458  0.252  1.0
  Mg  Mg6  1  0.918  0.374  0.568  1.0
  Mg  Mg7  1  0.394  0.516  0.422  1.0
  Si  Si8  1  0.597  0.321  0.058  1.0
  Si  Si9  1  0.403  0.645  0.962  1.0
  Si  Si10  1  0.043  0.379  0.138  1.0
  Si  Si11  1  0.830  0.817  0.905  1.0
  Si  Si12  1  0.482  0.172  0.671  1.0
  Si  Si13  1  0.831  0.716  0.319  1.0
  Si  Si14  1  0.229  0.780  0.539  1.0
  Si  Si15  1  0.091  0.115  0.447  1.0
  Si  Si16  1  0.693  0.809  0.621  1.0
  Si  Si17  1  0.628  0.089  0.365  1.0
  Si  Si18  1  0.854  0.757  0.176  1.0
  Si  Si19  1  0.255  0.510  0.844  1.0
[/CIF]
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The compound described by Mg2Si3 crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to one Si(3), two equivalent Si(10), two equivalent Si(11), and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(12), one Si(4), two equivalent Si(5), and two equivalent Si(9) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(2), one Si(3), two equivalent Si(1), and two equivalent Si(11) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(4), and two equivalent Si(12) atoms. In the fifth Mg site, Mg(5) is bonded in a 5-coordinate geometry to one Si(9), two equivalent Si(12), and two equivalent Si(5) atoms. In the sixth Mg site, Mg(6) is bonded in a 7-coordinate geometry to one Si(10), two equivalent Si(11), two equivalent Si(3), and two equivalent Si(6) atoms. In the seventh Mg site, Mg(7) is bonded in a 6-coordinate geometry to one Si(8), one Si(9), two equivalent Si(5), and two equivalent Si(7) atoms. In the eighth Mg site, Mg(8) is bonded in a 6-coordinate geometry to one Si(10), one Si(7), two equivalent Si(6), and two equivalent Si(8) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to one Mg(4), two equivalent Mg(3), one Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to one Mg(3), one Mg(4), one Si(1), one Si(12), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(6), one Si(11), 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 Mg(4), one Si(12), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to two equivalent Mg(2), two equivalent Mg(5), two equivalent Mg(7), and one Si(9) atom. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(6), two equivalent Mg(8), one Si(10), and one Si(11) atom. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to one Mg(8), two equivalent Mg(7), one Si(8), and two equivalent Si(9) atoms. In the eighth Si site, Si(8) is bonded in a 6-coordinate geometry to one Mg(7), two equivalent Mg(8), 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(5), one Mg(7), two equivalent Mg(2), one Si(5), and two equivalent Si(7) atoms. In the tenth Si site, Si(10) is bonded in a 7-coordinate geometry to one Mg(6), one Mg(8), two equivalent Mg(1), one Si(6), and two equivalent Si(8) atoms. In the eleventh Si site, Si(11) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(6), one Si(3), and one Si(6) atom. In the twelfth Si site, Si(12) is bonded in a 7-coordinate geometry to one Mg(2), two equivalent Mg(4), two equivalent Mg(5), one Si(2), and one Si(4) atom. is represented by the CIF file [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.860
_cell_length_b   6.230
_cell_length_c   17.453
_cell_angle_alpha   82.579
_cell_angle_beta   86.598
_cell_angle_gamma   72.365
_symmetry_Int_Tables_number   1
_cell_volume   396.467
_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  0.206  0.009  0.247  1.0
  Mg  Mg1  1  0.092  0.906  0.749  1.0
  Mg  Mg2  1  0.292  0.948  0.070  1.0
  Mg  Mg3  1  0.879  0.231  0.911  1.0
  Mg  Mg4  1  0.804  0.447  0.735  1.0
  Mg  Mg5  1  0.480  0.458  0.252  1.0
  Mg  Mg6  1  0.918  0.374  0.568  1.0
  Mg  Mg7  1  0.394  0.516  0.422  1.0
  Si  Si8  1  0.597  0.321  0.058  1.0
  Si  Si9  1  0.403  0.645  0.962  1.0
  Si  Si10  1  0.043  0.379  0.138  1.0
  Si  Si11  1  0.830  0.817  0.905  1.0
  Si  Si12  1  0.482  0.172  0.671  1.0
  Si  Si13  1  0.831  0.716  0.319  1.0
  Si  Si14  1  0.229  0.780  0.539  1.0
  Si  Si15  1  0.091  0.115  0.447  1.0
  Si  Si16  1  0.693  0.809  0.621  1.0
  Si  Si17  1  0.628  0.089  0.365  1.0
  Si  Si18  1  0.854  0.757  0.176  1.0
  Si  Si19  1  0.255  0.510  0.844  1.0
[/CIF]
.