The crystal structure described by MgEr2Tl2(WO4)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(13), one O(14), one O(15), one O(2), and one O(8) atom. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(11), one O(13), one O(15), one O(5), one O(6), one O(8), and one O(9) atom to form distorted ErO7 pentagonal bipyramids that share  a cornercorner with one W(3)O6 octahedra, corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, corners with two equivalent W(4)O6 octahedra, and  an edgeedge with one W(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-62°. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(10), one O(12), one O(14), one O(16), one O(5), one O(6), and one O(7) atom. There are four inequivalent W sites. In the first W site, W(1) is bonded to one O(1), one O(10), one O(13), one O(4), one O(7), and one O(9) atom to form WO6 octahedra that share corners with two equivalent W(4)O6 octahedra, corners with two equivalent Er(1)O7 pentagonal bipyramids, and  an edgeedge with one W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-44°. In the second W site, W(2) is bonded to one O(10), one O(14), one O(2), one O(3), one O(8), and one O(9) atom to form WO6 octahedra that share corners with two equivalent W(3)O6 octahedra, corners with two equivalent Er(1)O7 pentagonal bipyramids, and  an edgeedge with one W(1)O6 octahedra. The corner-sharing octahedral tilt angles are 45°. In the third W site, W(3) is bonded to one O(11), one O(12), one O(15), one O(2), one O(3), and one O(5) atom to form WO6 octahedra that share corners with two equivalent W(2)O6 octahedra,  a cornercorner with one Er(1)O7 pentagonal bipyramid,  an edgeedge with one W(4)O6 octahedra, and  an edgeedge with one Er(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 45°. In the fourth W site, W(4) is bonded to one O(1), one O(11), one O(12), one O(16), one O(4), and one O(6) atom to form WO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent Er(1)O7 pentagonal bipyramids, and  an edgeedge with one W(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-44°. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 3-coordinate geometry to one O(1), one O(10), and one O(3) atom. In the second Tl site, Tl(2) is bonded in a distorted single-bond geometry to one O(2) atom. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one W(1), one W(4), and one Tl(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one W(2), one W(3), and one Tl(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one W(2), one W(3), and one Tl(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one W(1) and one W(4) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Er(1), one Er(2), and one W(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Er(1), one Er(2), and one W(4) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Er(2) and one W(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Mg(1), one Er(1), and one W(2) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Er(1), one W(1), and one W(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal pyramidal geometry to one Er(2), one W(1), one W(2), and one Tl(1) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal non-coplanar geometry to one Er(1), one W(3), and one W(4) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Er(2), one W(3), and one W(4) atom. In the thirteenth O site, O(13) is bonded in a distorted T-shaped geometry to one Mg(1), one Er(1), and one W(1) atom. In the fourteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Mg(1), one Er(2), and one W(2) atom. In the fifteenth O site, O(15) is bonded in a distorted T-shaped geometry to one Mg(1), one Er(1), and one W(3) atom. In the sixteenth O site, O(16) is bonded in a bent 150 degrees geometry to one Er(2) and one W(4) atom. is represented by the CIF file [CIF]
data_Er2MgTl2(WO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.495
_cell_length_b   7.833
_cell_length_c   7.481
_cell_angle_alpha   64.022
_cell_angle_beta   63.463
_cell_angle_gamma   90.285
_symmetry_Int_Tables_number   1
_cell_volume   342.027
_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
  Er  Er0  1  0.266  0.784  0.734  1.0
  Er  Er1  1  0.761  0.199  0.251  1.0
  Mg  Mg2  1  0.923  0.965  0.876  1.0
  Tl  Tl3  1  0.751  0.262  0.726  1.0
  Tl  Tl4  1  0.222  0.800  0.239  1.0
  W  W5  1  0.289  0.316  0.700  1.0
  W  W6  1  0.703  0.667  0.316  1.0
  W  W7  1  0.688  0.698  0.805  1.0
  W  W8  1  0.309  0.290  0.205  1.0
  O  O9  1  0.377  0.241  0.945  1.0
  O  O10  1  0.632  0.761  0.050  1.0
  O  O11  1  0.768  0.613  0.573  1.0
  O  O12  1  0.248  0.373  0.429  1.0
  O  O13  1  0.612  0.912  0.635  1.0
  O  O14  1  0.390  0.071  0.359  1.0
  O  O15  1  0.047  0.353  0.884  1.0
  O  O16  1  0.959  0.663  0.104  1.0
  O  O17  1  0.411  0.627  0.534  1.0
  O  O18  1  0.597  0.357  0.471  1.0
  O  O19  1  0.373  0.579  0.969  1.0
  O  O20  1  0.639  0.418  0.030  1.0
  O  O21  1  0.213  0.037  0.795  1.0
  O  O22  1  0.787  0.954  0.185  1.0
  O  O23  1  0.966  0.805  0.697  1.0
  O  O24  1  0.034  0.213  0.307  1.0
[/CIF]
.
The crystal structure described by MgEr2Tl2(WO4)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(13), one O(14), one O(15), one O(2), and one O(8) atom. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(11), one O(13), one O(15), one O(5), one O(6), one O(8), and one O(9) atom to form distorted ErO7 pentagonal bipyramids that share  a cornercorner with one W(3)O6 octahedra, corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, corners with two equivalent W(4)O6 octahedra, and  an edgeedge with one W(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-62°. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(10), one O(12), one O(14), one O(16), one O(5), one O(6), and one O(7) atom. There are four inequivalent W sites. In the first W site, W(1) is bonded to one O(1), one O(10), one O(13), one O(4), one O(7), and one O(9) atom to form WO6 octahedra that share corners with two equivalent W(4)O6 octahedra, corners with two equivalent Er(1)O7 pentagonal bipyramids, and  an edgeedge with one W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-44°. In the second W site, W(2) is bonded to one O(10), one O(14), one O(2), one O(3), one O(8), and one O(9) atom to form WO6 octahedra that share corners with two equivalent W(3)O6 octahedra, corners with two equivalent Er(1)O7 pentagonal bipyramids, and  an edgeedge with one W(1)O6 octahedra. The corner-sharing octahedral tilt angles are 45°. In the third W site, W(3) is bonded to one O(11), one O(12), one O(15), one O(2), one O(3), and one O(5) atom to form WO6 octahedra that share corners with two equivalent W(2)O6 octahedra,  a cornercorner with one Er(1)O7 pentagonal bipyramid,  an edgeedge with one W(4)O6 octahedra, and  an edgeedge with one Er(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 45°. In the fourth W site, W(4) is bonded to one O(1), one O(11), one O(12), one O(16), one O(4), and one O(6) atom to form WO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent Er(1)O7 pentagonal bipyramids, and  an edgeedge with one W(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-44°. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 3-coordinate geometry to one O(1), one O(10), and one O(3) atom. In the second Tl site, Tl(2) is bonded in a distorted single-bond geometry to one O(2) atom. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one W(1), one W(4), and one Tl(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one W(2), one W(3), and one Tl(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one W(2), one W(3), and one Tl(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one W(1) and one W(4) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Er(1), one Er(2), and one W(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Er(1), one Er(2), and one W(4) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Er(2) and one W(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Mg(1), one Er(1), and one W(2) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Er(1), one W(1), and one W(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal pyramidal geometry to one Er(2), one W(1), one W(2), and one Tl(1) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal non-coplanar geometry to one Er(1), one W(3), and one W(4) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Er(2), one W(3), and one W(4) atom. In the thirteenth O site, O(13) is bonded in a distorted T-shaped geometry to one Mg(1), one Er(1), and one W(1) atom. In the fourteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Mg(1), one Er(2), and one W(2) atom. In the fifteenth O site, O(15) is bonded in a distorted T-shaped geometry to one Mg(1), one Er(1), and one W(3) atom. In the sixteenth O site, O(16) is bonded in a bent 150 degrees geometry to one Er(2) and one W(4) atom. is represented by the CIF file [CIF]
data_Er2MgTl2(WO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.495
_cell_length_b   7.833
_cell_length_c   7.481
_cell_angle_alpha   64.022
_cell_angle_beta   63.463
_cell_angle_gamma   90.285
_symmetry_Int_Tables_number   1
_cell_volume   342.027
_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
  Er  Er0  1  0.266  0.784  0.734  1.0
  Er  Er1  1  0.761  0.199  0.251  1.0
  Mg  Mg2  1  0.923  0.965  0.876  1.0
  Tl  Tl3  1  0.751  0.262  0.726  1.0
  Tl  Tl4  1  0.222  0.800  0.239  1.0
  W  W5  1  0.289  0.316  0.700  1.0
  W  W6  1  0.703  0.667  0.316  1.0
  W  W7  1  0.688  0.698  0.805  1.0
  W  W8  1  0.309  0.290  0.205  1.0
  O  O9  1  0.377  0.241  0.945  1.0
  O  O10  1  0.632  0.761  0.050  1.0
  O  O11  1  0.768  0.613  0.573  1.0
  O  O12  1  0.248  0.373  0.429  1.0
  O  O13  1  0.612  0.912  0.635  1.0
  O  O14  1  0.390  0.071  0.359  1.0
  O  O15  1  0.047  0.353  0.884  1.0
  O  O16  1  0.959  0.663  0.104  1.0
  O  O17  1  0.411  0.627  0.534  1.0
  O  O18  1  0.597  0.357  0.471  1.0
  O  O19  1  0.373  0.579  0.969  1.0
  O  O20  1  0.639  0.418  0.030  1.0
  O  O21  1  0.213  0.037  0.795  1.0
  O  O22  1  0.787  0.954  0.185  1.0
  O  O23  1  0.966  0.805  0.697  1.0
  O  O24  1  0.034  0.213  0.307  1.0
[/CIF]
.