The crystal structure described by Mg2Ir3 is Frank-Kasper $\mu$ Phase-like structured and crystallizes in the monoclinic C2/m space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 16-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(1), two equivalent Ir(6), three equivalent Ir(1), three equivalent Ir(4), and four equivalent Ir(2) atoms. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Ir(2), two equivalent Ir(3), two equivalent Ir(5), and four equivalent Ir(6) atoms. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to one Mg(1), two equivalent Ir(6), three equivalent Ir(4), three equivalent Ir(5), and four equivalent Ir(2) atoms. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one Mg(1), two equivalent Ir(1), two equivalent Ir(2), and two equivalent Ir(6) atoms. In the fifth Mg site, Mg(5) is bonded in a 8-coordinate geometry to one Ir(3), one Ir(5), two equivalent Ir(1), two equivalent Ir(2), and two equivalent Ir(6) atoms. There are six inequivalent Ir sites. In the first Ir site, Ir(1) is bonded to two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(1), one Ir(4), two equivalent Ir(2), and two equivalent Ir(6) atoms to form distorted IrMg7Ir5 cuboctahedra that share  a cornercorner with one Ir(3)Mg6Ir6 cuboctahedra,  a cornercorner with one Ir(5)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(4)Mg6Ir6 cuboctahedra, corners with four equivalent Ir(2)Mg7Ir5 cuboctahedra, edges with five equivalent Ir(1)Mg7Ir5 cuboctahedra,  a faceface with one Ir(3)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(5)Mg6Ir6 cuboctahedra, faces with three equivalent Ir(4)Mg6Ir6 cuboctahedra, and faces with six equivalent Ir(2)Mg7Ir5 cuboctahedra. In the second Ir site, Ir(2) is bonded to one Mg(2), one Mg(4), one Mg(5), two equivalent Mg(1), two equivalent Mg(3), one Ir(1), one Ir(4), one Ir(5), and two equivalent Ir(2) atoms to form distorted IrMg7Ir5 cuboctahedra that share  a cornercorner with one Ir(3)Mg6Ir6 cuboctahedra,  a cornercorner with one Ir(5)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(4)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(1)Mg7Ir5 cuboctahedra, corners with six equivalent Ir(2)Mg7Ir5 cuboctahedra, edges with two equivalent Ir(2)Mg7Ir5 cuboctahedra,  a faceface with one Ir(3)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(2)Mg7Ir5 cuboctahedra, faces with three equivalent Ir(5)Mg6Ir6 cuboctahedra, faces with three equivalent Ir(1)Mg7Ir5 cuboctahedra, and faces with four equivalent Ir(4)Mg6Ir6 cuboctahedra. In the third Ir site, Ir(3) is bonded to two equivalent Mg(5), four equivalent Mg(2), two equivalent Ir(5), and four equivalent Ir(6) atoms to form distorted IrMg6Ir6 cuboctahedra that share corners with two equivalent Ir(1)Mg7Ir5 cuboctahedra, corners with four equivalent Ir(5)Mg6Ir6 cuboctahedra, corners with four equivalent Ir(2)Mg7Ir5 cuboctahedra, edges with two equivalent Ir(3)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(4)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(5)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(1)Mg7Ir5 cuboctahedra, and faces with four equivalent Ir(2)Mg7Ir5 cuboctahedra. In the fourth Ir site, Ir(4) is bonded to three equivalent Mg(1), three equivalent Mg(3), one Ir(1), one Ir(5), two equivalent Ir(2), and two equivalent Ir(6) atoms to form IrMg6Ir6 cuboctahedra that share corners with two equivalent Ir(5)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(1)Mg7Ir5 cuboctahedra, corners with four equivalent Ir(2)Mg7Ir5 cuboctahedra, edges with six equivalent Ir(4)Mg6Ir6 cuboctahedra,  a faceface with one Ir(3)Mg6Ir6 cuboctahedra, faces with three equivalent Ir(5)Mg6Ir6 cuboctahedra, faces with three equivalent Ir(1)Mg7Ir5 cuboctahedra, and faces with eight equivalent Ir(2)Mg7Ir5 cuboctahedra. In the fifth Ir site, Ir(5) is bonded to one Mg(5), two equivalent Mg(2), three equivalent Mg(3), one Ir(3), one Ir(4), two equivalent Ir(2), and two equivalent Ir(6) atoms to form distorted IrMg6Ir6 cuboctahedra that share  a cornercorner with one Ir(5)Mg6Ir6 cuboctahedra,  a cornercorner with one Ir(1)Mg7Ir5 cuboctahedra, corners with two equivalent Ir(3)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(4)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(2)Mg7Ir5 cuboctahedra, edges with four equivalent Ir(5)Mg6Ir6 cuboctahedra,  a faceface with one Ir(3)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(1)Mg7Ir5 cuboctahedra, faces with three equivalent Ir(4)Mg6Ir6 cuboctahedra, and faces with six equivalent Ir(2)Mg7Ir5 cuboctahedra. In the sixth Ir site, Ir(6) is bonded in a 12-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), one Mg(5), two equivalent Mg(2), one Ir(1), one Ir(3), one Ir(4), one Ir(5), and two equivalent Ir(6) atoms. is represented by the CIF card [CIF]
data_Mg2Ir3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.184
_cell_length_b   8.522
_cell_length_c   9.656
_cell_angle_alpha   96.650
_cell_angle_beta   105.572
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   407.972
_cell_formula_units_Z   5
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  0.280  0.084  0.561  1.0
  Mg  Mg1  1  0.720  0.916  0.439  1.0
  Mg  Mg2  1  0.555  0.384  0.110  1.0
  Mg  Mg3  1  0.445  0.616  0.890  1.0
  Mg  Mg4  1  0.291  0.444  0.582  1.0
  Mg  Mg5  1  0.709  0.556  0.418  1.0
  Mg  Mg6  1  0.422  0.002  0.844  1.0
  Mg  Mg7  1  0.578  0.998  0.156  1.0
  Mg  Mg8  1  0.020  0.181  0.040  1.0
  Mg  Mg9  1  0.980  0.819  0.960  1.0
  Ir  Ir10  1  0.868  0.028  0.737  1.0
  Ir  Ir11  1  0.132  0.972  0.263  1.0
  Ir  Ir12  1  0.419  0.229  0.336  1.0
  Ir  Ir13  1  0.581  0.771  0.664  1.0
  Ir  Ir14  1  0.082  0.771  0.664  1.0
  Ir  Ir15  1  0.918  0.229  0.336  1.0
  Ir  Ir16  1  0.000  0.500  0.000  1.0
  Ir  Ir17  1  0.216  0.741  0.431  1.0
  Ir  Ir18  1  0.784  0.259  0.569  1.0
  Ir  Ir19  1  0.136  0.466  0.272  1.0
  Ir  Ir20  1  0.864  0.534  0.728  1.0
  Ir  Ir21  1  0.643  0.296  0.819  1.0
  Ir  Ir22  1  0.357  0.704  0.181  1.0
  Ir  Ir23  1  0.824  0.704  0.181  1.0
  Ir  Ir24  1  0.176  0.296  0.819  1.0
[/CIF]
.
The crystal structure described by Mg2Ir3 is Frank-Kasper $\mu$ Phase-like structured and crystallizes in the monoclinic C2/m space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 16-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(1), two equivalent Ir(6), three equivalent Ir(1), three equivalent Ir(4), and four equivalent Ir(2) atoms. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Ir(2), two equivalent Ir(3), two equivalent Ir(5), and four equivalent Ir(6) atoms. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to one Mg(1), two equivalent Ir(6), three equivalent Ir(4), three equivalent Ir(5), and four equivalent Ir(2) atoms. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one Mg(1), two equivalent Ir(1), two equivalent Ir(2), and two equivalent Ir(6) atoms. In the fifth Mg site, Mg(5) is bonded in a 8-coordinate geometry to one Ir(3), one Ir(5), two equivalent Ir(1), two equivalent Ir(2), and two equivalent Ir(6) atoms. There are six inequivalent Ir sites. In the first Ir site, Ir(1) is bonded to two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(1), one Ir(4), two equivalent Ir(2), and two equivalent Ir(6) atoms to form distorted IrMg7Ir5 cuboctahedra that share  a cornercorner with one Ir(3)Mg6Ir6 cuboctahedra,  a cornercorner with one Ir(5)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(4)Mg6Ir6 cuboctahedra, corners with four equivalent Ir(2)Mg7Ir5 cuboctahedra, edges with five equivalent Ir(1)Mg7Ir5 cuboctahedra,  a faceface with one Ir(3)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(5)Mg6Ir6 cuboctahedra, faces with three equivalent Ir(4)Mg6Ir6 cuboctahedra, and faces with six equivalent Ir(2)Mg7Ir5 cuboctahedra. In the second Ir site, Ir(2) is bonded to one Mg(2), one Mg(4), one Mg(5), two equivalent Mg(1), two equivalent Mg(3), one Ir(1), one Ir(4), one Ir(5), and two equivalent Ir(2) atoms to form distorted IrMg7Ir5 cuboctahedra that share  a cornercorner with one Ir(3)Mg6Ir6 cuboctahedra,  a cornercorner with one Ir(5)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(4)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(1)Mg7Ir5 cuboctahedra, corners with six equivalent Ir(2)Mg7Ir5 cuboctahedra, edges with two equivalent Ir(2)Mg7Ir5 cuboctahedra,  a faceface with one Ir(3)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(2)Mg7Ir5 cuboctahedra, faces with three equivalent Ir(5)Mg6Ir6 cuboctahedra, faces with three equivalent Ir(1)Mg7Ir5 cuboctahedra, and faces with four equivalent Ir(4)Mg6Ir6 cuboctahedra. In the third Ir site, Ir(3) is bonded to two equivalent Mg(5), four equivalent Mg(2), two equivalent Ir(5), and four equivalent Ir(6) atoms to form distorted IrMg6Ir6 cuboctahedra that share corners with two equivalent Ir(1)Mg7Ir5 cuboctahedra, corners with four equivalent Ir(5)Mg6Ir6 cuboctahedra, corners with four equivalent Ir(2)Mg7Ir5 cuboctahedra, edges with two equivalent Ir(3)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(4)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(5)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(1)Mg7Ir5 cuboctahedra, and faces with four equivalent Ir(2)Mg7Ir5 cuboctahedra. In the fourth Ir site, Ir(4) is bonded to three equivalent Mg(1), three equivalent Mg(3), one Ir(1), one Ir(5), two equivalent Ir(2), and two equivalent Ir(6) atoms to form IrMg6Ir6 cuboctahedra that share corners with two equivalent Ir(5)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(1)Mg7Ir5 cuboctahedra, corners with four equivalent Ir(2)Mg7Ir5 cuboctahedra, edges with six equivalent Ir(4)Mg6Ir6 cuboctahedra,  a faceface with one Ir(3)Mg6Ir6 cuboctahedra, faces with three equivalent Ir(5)Mg6Ir6 cuboctahedra, faces with three equivalent Ir(1)Mg7Ir5 cuboctahedra, and faces with eight equivalent Ir(2)Mg7Ir5 cuboctahedra. In the fifth Ir site, Ir(5) is bonded to one Mg(5), two equivalent Mg(2), three equivalent Mg(3), one Ir(3), one Ir(4), two equivalent Ir(2), and two equivalent Ir(6) atoms to form distorted IrMg6Ir6 cuboctahedra that share  a cornercorner with one Ir(5)Mg6Ir6 cuboctahedra,  a cornercorner with one Ir(1)Mg7Ir5 cuboctahedra, corners with two equivalent Ir(3)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(4)Mg6Ir6 cuboctahedra, corners with two equivalent Ir(2)Mg7Ir5 cuboctahedra, edges with four equivalent Ir(5)Mg6Ir6 cuboctahedra,  a faceface with one Ir(3)Mg6Ir6 cuboctahedra, faces with two equivalent Ir(1)Mg7Ir5 cuboctahedra, faces with three equivalent Ir(4)Mg6Ir6 cuboctahedra, and faces with six equivalent Ir(2)Mg7Ir5 cuboctahedra. In the sixth Ir site, Ir(6) is bonded in a 12-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), one Mg(5), two equivalent Mg(2), one Ir(1), one Ir(3), one Ir(4), one Ir(5), and two equivalent Ir(6) atoms. is represented by the CIF card [CIF]
data_Mg2Ir3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.184
_cell_length_b   8.522
_cell_length_c   9.656
_cell_angle_alpha   96.650
_cell_angle_beta   105.572
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   407.972
_cell_formula_units_Z   5
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  0.280  0.084  0.561  1.0
  Mg  Mg1  1  0.720  0.916  0.439  1.0
  Mg  Mg2  1  0.555  0.384  0.110  1.0
  Mg  Mg3  1  0.445  0.616  0.890  1.0
  Mg  Mg4  1  0.291  0.444  0.582  1.0
  Mg  Mg5  1  0.709  0.556  0.418  1.0
  Mg  Mg6  1  0.422  0.002  0.844  1.0
  Mg  Mg7  1  0.578  0.998  0.156  1.0
  Mg  Mg8  1  0.020  0.181  0.040  1.0
  Mg  Mg9  1  0.980  0.819  0.960  1.0
  Ir  Ir10  1  0.868  0.028  0.737  1.0
  Ir  Ir11  1  0.132  0.972  0.263  1.0
  Ir  Ir12  1  0.419  0.229  0.336  1.0
  Ir  Ir13  1  0.581  0.771  0.664  1.0
  Ir  Ir14  1  0.082  0.771  0.664  1.0
  Ir  Ir15  1  0.918  0.229  0.336  1.0
  Ir  Ir16  1  0.000  0.500  0.000  1.0
  Ir  Ir17  1  0.216  0.741  0.431  1.0
  Ir  Ir18  1  0.784  0.259  0.569  1.0
  Ir  Ir19  1  0.136  0.466  0.272  1.0
  Ir  Ir20  1  0.864  0.534  0.728  1.0
  Ir  Ir21  1  0.643  0.296  0.819  1.0
  Ir  Ir22  1  0.357  0.704  0.181  1.0
  Ir  Ir23  1  0.824  0.704  0.181  1.0
  Ir  Ir24  1  0.176  0.296  0.819  1.0
[/CIF]
.