The compound described by MgSi2 is Magnesium tetraboride-like structured and crystallizes in the triclinic P-1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 13-coordinate geometry to one Mg(1), one Mg(4), one Si(1), one Si(2), one Si(3), one Si(5), one Si(8), two equivalent Si(4), two equivalent Si(6), and two equivalent Si(7) atoms. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Si(3), one Si(8), two equivalent Si(2), and two equivalent Si(5) atoms. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Si(1), one Si(2), one Si(4), one Si(5), one Si(7), and two equivalent Si(3) atoms. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one Mg(1), one Si(4), one Si(5), one Si(8), two equivalent Si(2), and two equivalent Si(3) atoms. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(3), one Si(1), one Si(4), one Si(5), one Si(8), and two equivalent Si(7) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(2), two equivalent Mg(4), one Si(3), one Si(4), one Si(7), and one Si(8) atom. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Mg(1), one Mg(2), two equivalent Mg(3), two equivalent Mg(4), one Si(2), one Si(3), and one Si(5) atom. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(1), one Si(1), one Si(2), one Si(7), and two equivalent Si(6) atoms. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), two equivalent Mg(2), one Si(1), one Si(3), and one Si(8) atom. In the sixth Si site, Si(6) is bonded in a 6-coordinate geometry to two equivalent Mg(1), one Si(7), one Si(8), and two equivalent Si(4) atoms. In the seventh Si site, Si(7) is bonded in a 10-coordinate geometry to one Mg(3), two equivalent Mg(1), one Si(2), one Si(4), one Si(6), one Si(7), one Si(8), and two equivalent Si(1) atoms. In the eighth Si site, Si(8) is bonded in a 2-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Si(1), one Si(2), one Si(5), one Si(6), and one Si(7) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.376
_cell_length_b   7.236
_cell_length_c   9.620
_cell_angle_alpha   92.862
_cell_angle_beta   105.522
_cell_angle_gamma   97.347
_symmetry_Int_Tables_number   1
_cell_volume   422.503
_cell_formula_units_Z   8
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  0.864  0.399  0.857  1.0
  Mg  Mg1  1  0.136  0.601  0.143  1.0
  Mg  Mg2  1  0.213  0.938  0.463  1.0
  Mg  Mg3  1  0.467  0.239  0.304  1.0
  Mg  Mg4  1  0.168  0.403  0.631  1.0
  Mg  Mg5  1  0.832  0.597  0.369  1.0
  Mg  Mg6  1  0.533  0.761  0.696  1.0
  Mg  Mg7  1  0.787  0.062  0.537  1.0
  Si  Si8  1  0.664  0.054  0.954  1.0
  Si  Si9  1  0.049  0.268  0.334  1.0
  Si  Si10  1  0.342  0.574  0.424  1.0
  Si  Si11  1  0.705  0.347  0.121  1.0
  Si  Si12  1  0.503  0.147  0.704  1.0
  Si  Si13  1  0.688  0.652  0.028  1.0
  Si  Si14  1  0.295  0.653  0.879  1.0
  Si  Si15  1  0.060  0.162  0.091  1.0
  Si  Si16  1  0.951  0.732  0.666  1.0
  Si  Si17  1  0.312  0.348  0.972  1.0
  Si  Si18  1  0.940  0.838  0.909  1.0
  Si  Si19  1  0.497  0.853  0.296  1.0
  Si  Si20  1  0.162  0.089  0.778  1.0
  Si  Si21  1  0.658  0.426  0.576  1.0
  Si  Si22  1  0.838  0.911  0.222  1.0
  Si  Si23  1  0.336  0.946  0.046  1.0
[/CIF]
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The compound described by MgSi2 is Magnesium tetraboride-like structured and crystallizes in the triclinic P-1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 13-coordinate geometry to one Mg(1), one Mg(4), one Si(1), one Si(2), one Si(3), one Si(5), one Si(8), two equivalent Si(4), two equivalent Si(6), and two equivalent Si(7) atoms. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Si(3), one Si(8), two equivalent Si(2), and two equivalent Si(5) atoms. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Si(1), one Si(2), one Si(4), one Si(5), one Si(7), and two equivalent Si(3) atoms. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one Mg(1), one Si(4), one Si(5), one Si(8), two equivalent Si(2), and two equivalent Si(3) atoms. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(3), one Si(1), one Si(4), one Si(5), one Si(8), and two equivalent Si(7) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(2), two equivalent Mg(4), one Si(3), one Si(4), one Si(7), and one Si(8) atom. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Mg(1), one Mg(2), two equivalent Mg(3), two equivalent Mg(4), one Si(2), one Si(3), and one Si(5) atom. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(1), one Si(1), one Si(2), one Si(7), and two equivalent Si(6) atoms. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), two equivalent Mg(2), one Si(1), one Si(3), and one Si(8) atom. In the sixth Si site, Si(6) is bonded in a 6-coordinate geometry to two equivalent Mg(1), one Si(7), one Si(8), and two equivalent Si(4) atoms. In the seventh Si site, Si(7) is bonded in a 10-coordinate geometry to one Mg(3), two equivalent Mg(1), one Si(2), one Si(4), one Si(6), one Si(7), one Si(8), and two equivalent Si(1) atoms. In the eighth Si site, Si(8) is bonded in a 2-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Si(1), one Si(2), one Si(5), one Si(6), and one Si(7) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.376
_cell_length_b   7.236
_cell_length_c   9.620
_cell_angle_alpha   92.862
_cell_angle_beta   105.522
_cell_angle_gamma   97.347
_symmetry_Int_Tables_number   1
_cell_volume   422.503
_cell_formula_units_Z   8
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  0.864  0.399  0.857  1.0
  Mg  Mg1  1  0.136  0.601  0.143  1.0
  Mg  Mg2  1  0.213  0.938  0.463  1.0
  Mg  Mg3  1  0.467  0.239  0.304  1.0
  Mg  Mg4  1  0.168  0.403  0.631  1.0
  Mg  Mg5  1  0.832  0.597  0.369  1.0
  Mg  Mg6  1  0.533  0.761  0.696  1.0
  Mg  Mg7  1  0.787  0.062  0.537  1.0
  Si  Si8  1  0.664  0.054  0.954  1.0
  Si  Si9  1  0.049  0.268  0.334  1.0
  Si  Si10  1  0.342  0.574  0.424  1.0
  Si  Si11  1  0.705  0.347  0.121  1.0
  Si  Si12  1  0.503  0.147  0.704  1.0
  Si  Si13  1  0.688  0.652  0.028  1.0
  Si  Si14  1  0.295  0.653  0.879  1.0
  Si  Si15  1  0.060  0.162  0.091  1.0
  Si  Si16  1  0.951  0.732  0.666  1.0
  Si  Si17  1  0.312  0.348  0.972  1.0
  Si  Si18  1  0.940  0.838  0.909  1.0
  Si  Si19  1  0.497  0.853  0.296  1.0
  Si  Si20  1  0.162  0.089  0.778  1.0
  Si  Si21  1  0.658  0.426  0.576  1.0
  Si  Si22  1  0.838  0.911  0.222  1.0
  Si  Si23  1  0.336  0.946  0.046  1.0
[/CIF]
.