The compound described by MgY5 crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 10-coordinate geometry to one Y(4), two equivalent Y(1), two equivalent Y(3), two equivalent Y(5), and three equivalent Y(2) atoms. There are five inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent Mg(1), one Y(3), two equivalent Y(1), two equivalent Y(2), two equivalent Y(4), and three equivalent Y(5) atoms to form distorted YY10Mg2 cuboctahedra that share corners with six equivalent Y(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(4)Y11Mg cuboctahedra, corners with six equivalent Y(2)Y9Mg3 cuboctahedra, edges with two equivalent Y(5)Y10Mg2 cuboctahedra, edges with three equivalent Y(4)Y11Mg cuboctahedra, edges with three equivalent Y(2)Y9Mg3 cuboctahedra, edges with four equivalent Y(3)Y10Mg2 cuboctahedra, faces with two equivalent Y(1)Y10Mg2 cuboctahedra, faces with three equivalent Y(4)Y11Mg cuboctahedra, faces with three equivalent Y(2)Y9Mg3 cuboctahedra, faces with four equivalent Y(3)Y10Mg2 cuboctahedra, and faces with five equivalent Y(5)Y10Mg2 cuboctahedra. In the second Y site, Y(2) is bonded to three equivalent Mg(1), one Y(5), two equivalent Y(1), two equivalent Y(2), two equivalent Y(3), and two equivalent Y(4) atoms to form YY9Mg3 cuboctahedra that share corners with six equivalent Y(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(4)Y11Mg cuboctahedra, corners with six equivalent Y(2)Y9Mg3 cuboctahedra, edges with three equivalent Y(1)Y10Mg2 cuboctahedra, edges with three equivalent Y(4)Y11Mg cuboctahedra, edges with four equivalent Y(5)Y10Mg2 cuboctahedra, edges with six equivalent Y(3)Y10Mg2 cuboctahedra, faces with two equivalent Y(2)Y9Mg3 cuboctahedra, faces with three equivalent Y(1)Y10Mg2 cuboctahedra, faces with three equivalent Y(3)Y10Mg2 cuboctahedra, faces with three equivalent Y(4)Y11Mg cuboctahedra, and faces with four equivalent Y(5)Y10Mg2 cuboctahedra. In the third Y site, Y(3) is bonded to two equivalent Mg(1), one Y(1), two equivalent Y(2), two equivalent Y(3), two equivalent Y(5), and three equivalent Y(4) atoms to form distorted YY10Mg2 cuboctahedra that share corners with six equivalent Y(3)Y10Mg2 cuboctahedra, corners with six equivalent Y(5)Y10Mg2 cuboctahedra, edges with two equivalent Y(4)Y11Mg cuboctahedra, edges with three equivalent Y(5)Y10Mg2 cuboctahedra, edges with four equivalent Y(1)Y10Mg2 cuboctahedra, edges with six equivalent Y(2)Y9Mg3 cuboctahedra, faces with two equivalent Y(3)Y10Mg2 cuboctahedra, faces with three equivalent Y(5)Y10Mg2 cuboctahedra, faces with three equivalent Y(2)Y9Mg3 cuboctahedra, faces with four equivalent Y(1)Y10Mg2 cuboctahedra, and faces with five equivalent Y(4)Y11Mg cuboctahedra. In the fourth Y site, Y(4) is bonded to one Mg(1), two equivalent Y(1), two equivalent Y(2), two equivalent Y(4), two equivalent Y(5), and three equivalent Y(3) atoms to form YY11Mg cuboctahedra that share corners with six equivalent Y(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(4)Y11Mg cuboctahedra, corners with six equivalent Y(2)Y9Mg3 cuboctahedra, edges with two equivalent Y(3)Y10Mg2 cuboctahedra, edges with three equivalent Y(1)Y10Mg2 cuboctahedra, edges with three equivalent Y(2)Y9Mg3 cuboctahedra, edges with six equivalent Y(5)Y10Mg2 cuboctahedra, faces with two equivalent Y(4)Y11Mg cuboctahedra, faces with three equivalent Y(1)Y10Mg2 cuboctahedra, faces with three equivalent Y(5)Y10Mg2 cuboctahedra, faces with three equivalent Y(2)Y9Mg3 cuboctahedra, and faces with five equivalent Y(3)Y10Mg2 cuboctahedra. In the fifth Y site, Y(5) is bonded to two equivalent Mg(1), one Y(2), two equivalent Y(3), two equivalent Y(4), two equivalent Y(5), and three equivalent Y(1) atoms to form YY10Mg2 cuboctahedra that share corners with six equivalent Y(3)Y10Mg2 cuboctahedra, corners with six equivalent Y(5)Y10Mg2 cuboctahedra, edges with two equivalent Y(1)Y10Mg2 cuboctahedra, edges with three equivalent Y(3)Y10Mg2 cuboctahedra, edges with four equivalent Y(2)Y9Mg3 cuboctahedra, edges with six equivalent Y(4)Y11Mg cuboctahedra, faces with two equivalent Y(5)Y10Mg2 cuboctahedra, faces with three equivalent Y(3)Y10Mg2 cuboctahedra, faces with three equivalent Y(4)Y11Mg cuboctahedra, faces with four equivalent Y(2)Y9Mg3 cuboctahedra, and faces with five equivalent Y(1)Y10Mg2 cuboctahedra. is represented by the CIF file [CIF]
data_Y5Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.752
_cell_length_b   6.752
_cell_length_c   8.388
_cell_angle_alpha   74.885
_cell_angle_beta   74.885
_cell_angle_gamma   31.207
_symmetry_Int_Tables_number   1
_cell_volume   190.702
_cell_formula_units_Z   1
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
  Y  Y0  1  0.001  0.001  0.012  1.0
  Y  Y1  1  0.319  0.319  0.333  1.0
  Y  Y2  1  0.953  0.953  0.596  1.0
  Y  Y3  1  0.671  0.671  0.672  1.0
  Y  Y4  1  0.281  0.281  0.942  1.0
  Mg  Mg5  1  0.609  0.609  0.277  1.0
[/CIF]
.
The compound described by MgY5 crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 10-coordinate geometry to one Y(4), two equivalent Y(1), two equivalent Y(3), two equivalent Y(5), and three equivalent Y(2) atoms. There are five inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent Mg(1), one Y(3), two equivalent Y(1), two equivalent Y(2), two equivalent Y(4), and three equivalent Y(5) atoms to form distorted YY10Mg2 cuboctahedra that share corners with six equivalent Y(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(4)Y11Mg cuboctahedra, corners with six equivalent Y(2)Y9Mg3 cuboctahedra, edges with two equivalent Y(5)Y10Mg2 cuboctahedra, edges with three equivalent Y(4)Y11Mg cuboctahedra, edges with three equivalent Y(2)Y9Mg3 cuboctahedra, edges with four equivalent Y(3)Y10Mg2 cuboctahedra, faces with two equivalent Y(1)Y10Mg2 cuboctahedra, faces with three equivalent Y(4)Y11Mg cuboctahedra, faces with three equivalent Y(2)Y9Mg3 cuboctahedra, faces with four equivalent Y(3)Y10Mg2 cuboctahedra, and faces with five equivalent Y(5)Y10Mg2 cuboctahedra. In the second Y site, Y(2) is bonded to three equivalent Mg(1), one Y(5), two equivalent Y(1), two equivalent Y(2), two equivalent Y(3), and two equivalent Y(4) atoms to form YY9Mg3 cuboctahedra that share corners with six equivalent Y(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(4)Y11Mg cuboctahedra, corners with six equivalent Y(2)Y9Mg3 cuboctahedra, edges with three equivalent Y(1)Y10Mg2 cuboctahedra, edges with three equivalent Y(4)Y11Mg cuboctahedra, edges with four equivalent Y(5)Y10Mg2 cuboctahedra, edges with six equivalent Y(3)Y10Mg2 cuboctahedra, faces with two equivalent Y(2)Y9Mg3 cuboctahedra, faces with three equivalent Y(1)Y10Mg2 cuboctahedra, faces with three equivalent Y(3)Y10Mg2 cuboctahedra, faces with three equivalent Y(4)Y11Mg cuboctahedra, and faces with four equivalent Y(5)Y10Mg2 cuboctahedra. In the third Y site, Y(3) is bonded to two equivalent Mg(1), one Y(1), two equivalent Y(2), two equivalent Y(3), two equivalent Y(5), and three equivalent Y(4) atoms to form distorted YY10Mg2 cuboctahedra that share corners with six equivalent Y(3)Y10Mg2 cuboctahedra, corners with six equivalent Y(5)Y10Mg2 cuboctahedra, edges with two equivalent Y(4)Y11Mg cuboctahedra, edges with three equivalent Y(5)Y10Mg2 cuboctahedra, edges with four equivalent Y(1)Y10Mg2 cuboctahedra, edges with six equivalent Y(2)Y9Mg3 cuboctahedra, faces with two equivalent Y(3)Y10Mg2 cuboctahedra, faces with three equivalent Y(5)Y10Mg2 cuboctahedra, faces with three equivalent Y(2)Y9Mg3 cuboctahedra, faces with four equivalent Y(1)Y10Mg2 cuboctahedra, and faces with five equivalent Y(4)Y11Mg cuboctahedra. In the fourth Y site, Y(4) is bonded to one Mg(1), two equivalent Y(1), two equivalent Y(2), two equivalent Y(4), two equivalent Y(5), and three equivalent Y(3) atoms to form YY11Mg cuboctahedra that share corners with six equivalent Y(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(4)Y11Mg cuboctahedra, corners with six equivalent Y(2)Y9Mg3 cuboctahedra, edges with two equivalent Y(3)Y10Mg2 cuboctahedra, edges with three equivalent Y(1)Y10Mg2 cuboctahedra, edges with three equivalent Y(2)Y9Mg3 cuboctahedra, edges with six equivalent Y(5)Y10Mg2 cuboctahedra, faces with two equivalent Y(4)Y11Mg cuboctahedra, faces with three equivalent Y(1)Y10Mg2 cuboctahedra, faces with three equivalent Y(5)Y10Mg2 cuboctahedra, faces with three equivalent Y(2)Y9Mg3 cuboctahedra, and faces with five equivalent Y(3)Y10Mg2 cuboctahedra. In the fifth Y site, Y(5) is bonded to two equivalent Mg(1), one Y(2), two equivalent Y(3), two equivalent Y(4), two equivalent Y(5), and three equivalent Y(1) atoms to form YY10Mg2 cuboctahedra that share corners with six equivalent Y(3)Y10Mg2 cuboctahedra, corners with six equivalent Y(5)Y10Mg2 cuboctahedra, edges with two equivalent Y(1)Y10Mg2 cuboctahedra, edges with three equivalent Y(3)Y10Mg2 cuboctahedra, edges with four equivalent Y(2)Y9Mg3 cuboctahedra, edges with six equivalent Y(4)Y11Mg cuboctahedra, faces with two equivalent Y(5)Y10Mg2 cuboctahedra, faces with three equivalent Y(3)Y10Mg2 cuboctahedra, faces with three equivalent Y(4)Y11Mg cuboctahedra, faces with four equivalent Y(2)Y9Mg3 cuboctahedra, and faces with five equivalent Y(1)Y10Mg2 cuboctahedra. is represented by the CIF file [CIF]
data_Y5Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.752
_cell_length_b   6.752
_cell_length_c   8.388
_cell_angle_alpha   74.885
_cell_angle_beta   74.885
_cell_angle_gamma   31.207
_symmetry_Int_Tables_number   1
_cell_volume   190.702
_cell_formula_units_Z   1
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
  Y  Y0  1  0.001  0.001  0.012  1.0
  Y  Y1  1  0.319  0.319  0.333  1.0
  Y  Y2  1  0.953  0.953  0.596  1.0
  Y  Y3  1  0.671  0.671  0.672  1.0
  Y  Y4  1  0.281  0.281  0.942  1.0
  Mg  Mg5  1  0.609  0.609  0.277  1.0
[/CIF]
.