The compound described by Mg4Si3 crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to one Mg(2), one Mg(3), one Si(2), one Si(4), and one Si(5) atom. In the second Mg site, Mg(2) is bonded in a 3-coordinate geometry to one Mg(1), one Si(1), one Si(3), one Si(4), and one Si(5) atom. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(6), one Si(2), one Si(5), and one Si(6) atom. In the fourth Mg site, Mg(4) is bonded in a 1-coordinate geometry to one Mg(6), one Si(1), one Si(3), and one Si(5) atom. In the fifth Mg site, Mg(5) is bonded in a 2-coordinate geometry to one Mg(6), one Si(2), and one Si(5) atom. In the sixth Mg site, Mg(6) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(4), one Mg(5), one Mg(7), one Si(1), one Si(4), and one Si(5) atom. In the seventh Mg site, Mg(7) is bonded in a distorted bent 150 degrees geometry to one Mg(6), one Si(1), one Si(2), and one Si(5) atom. In the eighth Mg site, Mg(8) is bonded in a 3-coordinate geometry to one Si(3), one Si(4), and one Si(6) atom. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 2-coordinate geometry to one Mg(2), one Mg(4), one Mg(6), and one Mg(7) atom. In the second Si site, Si(2) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(3), one Mg(5), and one Mg(7) atom. In the third Si site, Si(3) is bonded in a 4-coordinate geometry to one Mg(2), one Mg(4), one Mg(8), and one Si(6) atom. In the fourth Si site, Si(4) is bonded in a distorted single-bond geometry to one Mg(1), one Mg(2), one Mg(6), one Mg(8), and one Si(5) atom. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Mg(4), one Mg(5), one Mg(6), one Mg(7), and one Si(4) atom. In the sixth Si site, Si(6) is bonded in a 1-coordinate geometry to one Mg(3), one Mg(8), and one Si(3) atom. is represented by the CIF card [CIF]
data_Mg4Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.313
_cell_length_b   7.084
_cell_length_c   7.608
_cell_angle_alpha   115.294
_cell_angle_beta   105.074
_cell_angle_gamma   97.729
_symmetry_Int_Tables_number   1
_cell_volume   285.011
_cell_formula_units_Z   2
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  0.783  0.382  0.459  1.0
  Mg  Mg1  1  0.917  0.155  0.154  1.0
  Mg  Mg2  1  0.031  0.582  0.786  1.0
  Mg  Mg3  1  0.571  0.907  0.458  1.0
  Mg  Mg4  1  0.267  0.191  0.541  1.0
  Mg  Mg5  1  0.226  0.683  0.174  1.0
  Mg  Mg6  1  0.564  0.603  0.944  1.0
  Mg  Mg7  1  0.333  0.152  0.949  1.0
  Si  Si8  1  0.689  0.806  0.198  1.0
  Si  Si9  1  0.630  0.404  0.739  1.0
  Si  Si10  1  0.674  0.020  0.845  1.0
  Si  Si11  1  0.337  0.309  0.194  1.0
  Si  Si12  1  0.254  0.589  0.555  1.0
  Si  Si13  1  0.975  0.967  0.755  1.0
[/CIF]
.
The compound described by Mg4Si3 crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to one Mg(2), one Mg(3), one Si(2), one Si(4), and one Si(5) atom. In the second Mg site, Mg(2) is bonded in a 3-coordinate geometry to one Mg(1), one Si(1), one Si(3), one Si(4), and one Si(5) atom. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(6), one Si(2), one Si(5), and one Si(6) atom. In the fourth Mg site, Mg(4) is bonded in a 1-coordinate geometry to one Mg(6), one Si(1), one Si(3), and one Si(5) atom. In the fifth Mg site, Mg(5) is bonded in a 2-coordinate geometry to one Mg(6), one Si(2), and one Si(5) atom. In the sixth Mg site, Mg(6) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(4), one Mg(5), one Mg(7), one Si(1), one Si(4), and one Si(5) atom. In the seventh Mg site, Mg(7) is bonded in a distorted bent 150 degrees geometry to one Mg(6), one Si(1), one Si(2), and one Si(5) atom. In the eighth Mg site, Mg(8) is bonded in a 3-coordinate geometry to one Si(3), one Si(4), and one Si(6) atom. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 2-coordinate geometry to one Mg(2), one Mg(4), one Mg(6), and one Mg(7) atom. In the second Si site, Si(2) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(3), one Mg(5), and one Mg(7) atom. In the third Si site, Si(3) is bonded in a 4-coordinate geometry to one Mg(2), one Mg(4), one Mg(8), and one Si(6) atom. In the fourth Si site, Si(4) is bonded in a distorted single-bond geometry to one Mg(1), one Mg(2), one Mg(6), one Mg(8), and one Si(5) atom. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Mg(4), one Mg(5), one Mg(6), one Mg(7), and one Si(4) atom. In the sixth Si site, Si(6) is bonded in a 1-coordinate geometry to one Mg(3), one Mg(8), and one Si(3) atom. is represented by the CIF card [CIF]
data_Mg4Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.313
_cell_length_b   7.084
_cell_length_c   7.608
_cell_angle_alpha   115.294
_cell_angle_beta   105.074
_cell_angle_gamma   97.729
_symmetry_Int_Tables_number   1
_cell_volume   285.011
_cell_formula_units_Z   2
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  0.783  0.382  0.459  1.0
  Mg  Mg1  1  0.917  0.155  0.154  1.0
  Mg  Mg2  1  0.031  0.582  0.786  1.0
  Mg  Mg3  1  0.571  0.907  0.458  1.0
  Mg  Mg4  1  0.267  0.191  0.541  1.0
  Mg  Mg5  1  0.226  0.683  0.174  1.0
  Mg  Mg6  1  0.564  0.603  0.944  1.0
  Mg  Mg7  1  0.333  0.152  0.949  1.0
  Si  Si8  1  0.689  0.806  0.198  1.0
  Si  Si9  1  0.630  0.404  0.739  1.0
  Si  Si10  1  0.674  0.020  0.845  1.0
  Si  Si11  1  0.337  0.309  0.194  1.0
  Si  Si12  1  0.254  0.589  0.555  1.0
  Si  Si13  1  0.975  0.967  0.755  1.0
[/CIF]
.