The material described by Mg5Si6 is Magnesium tetraboride-like structured and crystallizes in the monoclinic P2_1 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to one Mg(3), one Si(3), one Si(4), one Si(5), one Si(6), two equivalent Si(1), and two equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to one Si(1), one Si(2), one Si(3), one Si(5), two equivalent Si(4), and two equivalent Si(6) atoms. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to one Mg(1), one Mg(5), two equivalent Mg(4), one Si(2), one Si(3), one Si(4), one Si(6), two equivalent Si(1), and two equivalent Si(5) atoms. In the fourth Mg site, Mg(4) is bonded in a 7-coordinate geometry to two equivalent Mg(3), one Si(1), one Si(2), one Si(4), one Si(5), one Si(6), and two equivalent Si(3) atoms. In the fifth Mg site, Mg(5) is bonded in a 4-coordinate geometry to one Mg(3), one Si(2), one Si(4), two equivalent Si(1), and two equivalent Si(6) atoms. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 11-coordinate geometry to one Mg(2), one Mg(4), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(5), one Si(2), one Si(3), and one Si(6) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Mg(5), two equivalent Mg(1), one Si(1), and one Si(3) atom. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), two equivalent Mg(4), one Si(1), one Si(2), one Si(4), and one Si(5) atom. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), one Mg(5), two equivalent Mg(2), one Si(3), one Si(5), and one Si(6) atom. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), two equivalent Mg(3), one Si(3), one Si(4), and one Si(6) atom. In the sixth Si site, Si(6) is bonded in a 10-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), two equivalent Mg(2), two equivalent Mg(5), one Si(1), one Si(4), and one Si(5) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg5Si6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.672
_cell_length_b   5.263
_cell_length_c   5.509
_cell_angle_alpha   83.735
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   394.047
_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  0.993  0.981  0.709  1.0
  Mg  Mg1  1  0.493  0.019  0.291  1.0
  Mg  Mg2  1  0.351  0.464  0.456  1.0
  Mg  Mg3  1  0.613  0.823  0.779  1.0
  Mg  Mg4  1  0.851  0.536  0.544  1.0
  Mg  Mg5  1  0.192  0.700  0.009  1.0
  Mg  Mg6  1  0.391  0.846  0.829  1.0
  Mg  Mg7  1  0.692  0.300  0.991  1.0
  Mg  Mg8  1  0.891  0.154  0.171  1.0
  Mg  Mg9  1  0.113  0.177  0.221  1.0
  Si  Si10  1  0.002  0.696  0.225  1.0
  Si  Si11  1  0.017  0.469  0.858  1.0
  Si  Si12  1  0.502  0.304  0.775  1.0
  Si  Si13  1  0.517  0.531  0.142  1.0
  Si  Si14  1  0.141  0.603  0.526  1.0
  Si  Si15  1  0.788  0.043  0.624  1.0
  Si  Si16  1  0.641  0.397  0.474  1.0
  Si  Si17  1  0.194  0.158  0.697  1.0
  Si  Si18  1  0.288  0.957  0.376  1.0
  Si  Si19  1  0.820  0.712  0.996  1.0
  Si  Si20  1  0.694  0.842  0.303  1.0
  Si  Si21  1  0.320  0.288  0.004  1.0
[/CIF]
.
The material described by Mg5Si6 is Magnesium tetraboride-like structured and crystallizes in the monoclinic P2_1 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to one Mg(3), one Si(3), one Si(4), one Si(5), one Si(6), two equivalent Si(1), and two equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to one Si(1), one Si(2), one Si(3), one Si(5), two equivalent Si(4), and two equivalent Si(6) atoms. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to one Mg(1), one Mg(5), two equivalent Mg(4), one Si(2), one Si(3), one Si(4), one Si(6), two equivalent Si(1), and two equivalent Si(5) atoms. In the fourth Mg site, Mg(4) is bonded in a 7-coordinate geometry to two equivalent Mg(3), one Si(1), one Si(2), one Si(4), one Si(5), one Si(6), and two equivalent Si(3) atoms. In the fifth Mg site, Mg(5) is bonded in a 4-coordinate geometry to one Mg(3), one Si(2), one Si(4), two equivalent Si(1), and two equivalent Si(6) atoms. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 11-coordinate geometry to one Mg(2), one Mg(4), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(5), one Si(2), one Si(3), and one Si(6) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Mg(5), two equivalent Mg(1), one Si(1), and one Si(3) atom. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), two equivalent Mg(4), one Si(1), one Si(2), one Si(4), and one Si(5) atom. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), one Mg(5), two equivalent Mg(2), one Si(3), one Si(5), and one Si(6) atom. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), two equivalent Mg(3), one Si(3), one Si(4), and one Si(6) atom. In the sixth Si site, Si(6) is bonded in a 10-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), two equivalent Mg(2), two equivalent Mg(5), one Si(1), one Si(4), and one Si(5) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg5Si6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.672
_cell_length_b   5.263
_cell_length_c   5.509
_cell_angle_alpha   83.735
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   394.047
_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  0.993  0.981  0.709  1.0
  Mg  Mg1  1  0.493  0.019  0.291  1.0
  Mg  Mg2  1  0.351  0.464  0.456  1.0
  Mg  Mg3  1  0.613  0.823  0.779  1.0
  Mg  Mg4  1  0.851  0.536  0.544  1.0
  Mg  Mg5  1  0.192  0.700  0.009  1.0
  Mg  Mg6  1  0.391  0.846  0.829  1.0
  Mg  Mg7  1  0.692  0.300  0.991  1.0
  Mg  Mg8  1  0.891  0.154  0.171  1.0
  Mg  Mg9  1  0.113  0.177  0.221  1.0
  Si  Si10  1  0.002  0.696  0.225  1.0
  Si  Si11  1  0.017  0.469  0.858  1.0
  Si  Si12  1  0.502  0.304  0.775  1.0
  Si  Si13  1  0.517  0.531  0.142  1.0
  Si  Si14  1  0.141  0.603  0.526  1.0
  Si  Si15  1  0.788  0.043  0.624  1.0
  Si  Si16  1  0.641  0.397  0.474  1.0
  Si  Si17  1  0.194  0.158  0.697  1.0
  Si  Si18  1  0.288  0.957  0.376  1.0
  Si  Si19  1  0.820  0.712  0.996  1.0
  Si  Si20  1  0.694  0.842  0.303  1.0
  Si  Si21  1  0.320  0.288  0.004  1.0
[/CIF]
.