The material described by MgTl4Al4O12 crystallizes in the monoclinic Pm space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one Tl(4), one O(1), one O(4), and two equivalent O(7) atoms. There are four inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 6-coordinate geometry to one O(5), one O(8), two equivalent O(2), and two equivalent O(3) atoms. In the second Tl site, Tl(2) is bonded in a 6-coordinate geometry to one O(5), one O(8), two equivalent O(3), and two equivalent O(6) atoms. In the third Tl site, Tl(3) is bonded in a 4-coordinate geometry to one O(1), one O(4), and two equivalent O(6) atoms. In the fourth Tl site, Tl(4) is bonded in a 5-coordinate geometry to one Mg(1), one O(1), one O(4), and two equivalent O(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form AlO6 octahedra that share corners with two equivalent Al(1)O6 octahedra and corners with three equivalent Al(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 22-37°. In the second Al site, Al(2) is bonded to one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form AlO5 trigonal bipyramids that share corners with three equivalent Al(1)O6 octahedra and corners with two equivalent Al(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 27-43°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Tl(3), one Tl(4), and two equivalent Al(1) atoms to form a mixture of distorted corner and edge-sharing OMgAl2Tl2 trigonal bipyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Tl(1), one Tl(4), one Al(1), and one Al(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Tl(1), one Tl(2), and one Al(1) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Tl(3), one Tl(4), and two equivalent Al(2) atoms to form OMgAl2Tl2 trigonal bipyramids that share  a cornercorner with one O(1)MgAl2Tl2 trigonal bipyramid, corners with two equivalent O(5)Al2Tl2 trigonal pyramids, and  an edgeedge with one O(1)MgAl2Tl2 trigonal bipyramid. In the fifth O site, O(5) is bonded to one Tl(1), one Tl(2), and two equivalent Al(2) atoms to form distorted corner-sharing OAl2Tl2 trigonal pyramids. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Tl(2), one Tl(3), one Al(1), and one Al(2) atom. In the seventh O site, O(7) is bonded in a T-shaped geometry to one Mg(1), one Al(1), and one Al(2) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Tl(1), one Tl(2), and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_MgAl4Tl4O12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.684
_cell_length_b   5.982
_cell_length_c   7.895
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   71.857
_symmetry_Int_Tables_number   1
_cell_volume   255.108
_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
  Mg  Mg0  1  0.803  0.778  0.250  1.0
  Al  Al1  1  0.976  0.477  0.969  1.0
  Al  Al2  1  0.976  0.477  0.531  1.0
  Al  Al3  1  0.568  0.064  0.986  1.0
  Al  Al4  1  0.568  0.064  0.514  1.0
  Tl  Tl5  1  0.070  0.983  0.750  1.0
  Tl  Tl6  1  0.500  0.494  0.750  1.0
  Tl  Tl7  1  0.449  0.468  0.250  1.0
  Tl  Tl8  1  0.125  0.033  0.250  1.0
  O  O9  1  0.055  0.464  0.250  1.0
  O  O10  1  0.232  0.176  0.543  1.0
  O  O11  1  0.232  0.176  0.957  1.0
  O  O12  1  0.202  0.654  0.934  1.0
  O  O13  1  0.202  0.654  0.566  1.0
  O  O14  1  0.517  0.070  0.250  1.0
  O  O15  1  0.647  0.073  0.750  1.0
  O  O16  1  0.709  0.305  0.032  1.0
  O  O17  1  0.709  0.305  0.468  1.0
  O  O18  1  0.723  0.757  0.014  1.0
  O  O19  1  0.723  0.757  0.486  1.0
  O  O20  1  0.890  0.444  0.750  1.0
[/CIF]
.
The material described by MgTl4Al4O12 crystallizes in the monoclinic Pm space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one Tl(4), one O(1), one O(4), and two equivalent O(7) atoms. There are four inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 6-coordinate geometry to one O(5), one O(8), two equivalent O(2), and two equivalent O(3) atoms. In the second Tl site, Tl(2) is bonded in a 6-coordinate geometry to one O(5), one O(8), two equivalent O(3), and two equivalent O(6) atoms. In the third Tl site, Tl(3) is bonded in a 4-coordinate geometry to one O(1), one O(4), and two equivalent O(6) atoms. In the fourth Tl site, Tl(4) is bonded in a 5-coordinate geometry to one Mg(1), one O(1), one O(4), and two equivalent O(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form AlO6 octahedra that share corners with two equivalent Al(1)O6 octahedra and corners with three equivalent Al(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 22-37°. In the second Al site, Al(2) is bonded to one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form AlO5 trigonal bipyramids that share corners with three equivalent Al(1)O6 octahedra and corners with two equivalent Al(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 27-43°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Tl(3), one Tl(4), and two equivalent Al(1) atoms to form a mixture of distorted corner and edge-sharing OMgAl2Tl2 trigonal bipyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Tl(1), one Tl(4), one Al(1), and one Al(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Tl(1), one Tl(2), and one Al(1) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Tl(3), one Tl(4), and two equivalent Al(2) atoms to form OMgAl2Tl2 trigonal bipyramids that share  a cornercorner with one O(1)MgAl2Tl2 trigonal bipyramid, corners with two equivalent O(5)Al2Tl2 trigonal pyramids, and  an edgeedge with one O(1)MgAl2Tl2 trigonal bipyramid. In the fifth O site, O(5) is bonded to one Tl(1), one Tl(2), and two equivalent Al(2) atoms to form distorted corner-sharing OAl2Tl2 trigonal pyramids. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Tl(2), one Tl(3), one Al(1), and one Al(2) atom. In the seventh O site, O(7) is bonded in a T-shaped geometry to one Mg(1), one Al(1), and one Al(2) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Tl(1), one Tl(2), and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_MgAl4Tl4O12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.684
_cell_length_b   5.982
_cell_length_c   7.895
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   71.857
_symmetry_Int_Tables_number   1
_cell_volume   255.108
_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
  Mg  Mg0  1  0.803  0.778  0.250  1.0
  Al  Al1  1  0.976  0.477  0.969  1.0
  Al  Al2  1  0.976  0.477  0.531  1.0
  Al  Al3  1  0.568  0.064  0.986  1.0
  Al  Al4  1  0.568  0.064  0.514  1.0
  Tl  Tl5  1  0.070  0.983  0.750  1.0
  Tl  Tl6  1  0.500  0.494  0.750  1.0
  Tl  Tl7  1  0.449  0.468  0.250  1.0
  Tl  Tl8  1  0.125  0.033  0.250  1.0
  O  O9  1  0.055  0.464  0.250  1.0
  O  O10  1  0.232  0.176  0.543  1.0
  O  O11  1  0.232  0.176  0.957  1.0
  O  O12  1  0.202  0.654  0.934  1.0
  O  O13  1  0.202  0.654  0.566  1.0
  O  O14  1  0.517  0.070  0.250  1.0
  O  O15  1  0.647  0.073  0.750  1.0
  O  O16  1  0.709  0.305  0.032  1.0
  O  O17  1  0.709  0.305  0.468  1.0
  O  O18  1  0.723  0.757  0.014  1.0
  O  O19  1  0.723  0.757  0.486  1.0
  O  O20  1  0.890  0.444  0.750  1.0
[/CIF]
.