The compound described by ErTl2P2Se7 crystallizes in the monoclinic C2/c space group. Er(1) is bonded in a 7-coordinate geometry to one Se(2), one Se(3), one Se(5), one Se(6), one Se(7), and two equivalent Se(4) atoms. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 3-coordinate geometry to one Se(1), one Se(3), and one Se(6) atom. In the second Tl site, Tl(2) is bonded in a distorted single-bond geometry to one Se(6) atom. There are two inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one Se(3), one Se(4), one Se(5), and one Se(6) atom. In the second P site, P(2) is bonded in a distorted tetrahedral geometry to one P(2), one Se(1), one Se(2), and one Se(7) atom. There are seven inequivalent Se sites. In the first Se site, Se(7) is bonded in an L-shaped geometry to one Er(1) and one P(2) atom. In the second Se site, Se(1) is bonded in a distorted L-shaped geometry to one Tl(1) and one P(2) atom. In the third Se site, Se(2) is bonded in an L-shaped geometry to one Er(1) and one P(2) atom. In the fourth Se site, Se(6) is bonded in a 4-coordinate geometry to one Er(1), one Tl(1), one Tl(2), and one P(1) atom. In the fifth Se site, Se(3) is bonded in a 3-coordinate geometry to one Er(1), one Tl(1), and one P(1) atom. In the sixth Se site, Se(4) is bonded in a distorted T-shaped geometry to two equivalent Er(1) and one P(1) atom. In the seventh Se site, Se(5) is bonded in an L-shaped geometry to one Er(1) and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_ErTl2P2Se7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.503
_cell_length_b   12.503
_cell_length_c   19.148
_cell_angle_alpha   62.131
_cell_angle_beta   62.131
_cell_angle_gamma   32.559
_symmetry_Int_Tables_number   1
_cell_volume   1406.951
_cell_formula_units_Z   4
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  0.891  0.786  0.241  1.0
  Er  Er1  1  0.214  0.109  0.259  1.0
  Er  Er2  1  0.109  0.214  0.759  1.0
  Er  Er3  1  0.786  0.891  0.741  1.0
  Tl  Tl4  1  0.834  0.821  0.019  1.0
  Tl  Tl5  1  0.179  0.166  0.481  1.0
  Tl  Tl6  1  0.166  0.179  0.981  1.0
  Tl  Tl7  1  0.821  0.834  0.519  1.0
  Tl  Tl8  1  0.541  0.466  0.128  1.0
  Tl  Tl9  1  0.534  0.459  0.372  1.0
  Tl  Tl10  1  0.459  0.534  0.872  1.0
  Tl  Tl11  1  0.466  0.541  0.628  1.0
  P  P12  1  0.682  0.658  0.358  1.0
  P  P13  1  0.342  0.318  0.142  1.0
  P  P14  1  0.318  0.342  0.642  1.0
  P  P15  1  0.658  0.682  0.858  1.0
  P  P16  1  0.986  0.920  0.307  1.0
  P  P17  1  0.080  0.014  0.193  1.0
  P  P18  1  0.014  0.080  0.693  1.0
  P  P19  1  0.920  0.986  0.807  1.0
  Se  Se20  1  0.005  0.947  0.402  1.0
  Se  Se21  1  0.053  0.995  0.098  1.0
  Se  Se22  1  0.995  0.053  0.598  1.0
  Se  Se23  1  0.947  0.005  0.902  1.0
  Se  Se24  1  0.192  0.614  0.302  1.0
  Se  Se25  1  0.386  0.808  0.198  1.0
  Se  Se26  1  0.808  0.386  0.698  1.0
  Se  Se27  1  0.614  0.192  0.802  1.0
  Se  Se28  1  0.169  0.626  0.091  1.0
  Se  Se29  1  0.374  0.831  0.409  1.0
  Se  Se30  1  0.831  0.374  0.909  1.0
  Se  Se31  1  0.626  0.169  0.591  1.0
  Se  Se32  1  0.225  0.326  0.272  1.0
  Se  Se33  1  0.674  0.775  0.228  1.0
  Se  Se34  1  0.775  0.674  0.728  1.0
  Se  Se35  1  0.326  0.225  0.772  1.0
  Se  Se36  1  0.764  0.711  0.404  1.0
  Se  Se37  1  0.289  0.236  0.096  1.0
  Se  Se38  1  0.236  0.289  0.596  1.0
  Se  Se39  1  0.711  0.764  0.904  1.0
  Se  Se40  1  0.880  0.339  0.389  1.0
  Se  Se41  1  0.661  0.120  0.111  1.0
  Se  Se42  1  0.120  0.661  0.611  1.0
  Se  Se43  1  0.339  0.880  0.889  1.0
  Se  Se44  1  0.888  0.314  0.198  1.0
  Se  Se45  1  0.686  0.112  0.302  1.0
  Se  Se46  1  0.112  0.686  0.802  1.0
  Se  Se47  1  0.314  0.888  0.698  1.0
[/CIF]
.
The compound described by ErTl2P2Se7 crystallizes in the monoclinic C2/c space group. Er(1) is bonded in a 7-coordinate geometry to one Se(2), one Se(3), one Se(5), one Se(6), one Se(7), and two equivalent Se(4) atoms. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 3-coordinate geometry to one Se(1), one Se(3), and one Se(6) atom. In the second Tl site, Tl(2) is bonded in a distorted single-bond geometry to one Se(6) atom. There are two inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one Se(3), one Se(4), one Se(5), and one Se(6) atom. In the second P site, P(2) is bonded in a distorted tetrahedral geometry to one P(2), one Se(1), one Se(2), and one Se(7) atom. There are seven inequivalent Se sites. In the first Se site, Se(7) is bonded in an L-shaped geometry to one Er(1) and one P(2) atom. In the second Se site, Se(1) is bonded in a distorted L-shaped geometry to one Tl(1) and one P(2) atom. In the third Se site, Se(2) is bonded in an L-shaped geometry to one Er(1) and one P(2) atom. In the fourth Se site, Se(6) is bonded in a 4-coordinate geometry to one Er(1), one Tl(1), one Tl(2), and one P(1) atom. In the fifth Se site, Se(3) is bonded in a 3-coordinate geometry to one Er(1), one Tl(1), and one P(1) atom. In the sixth Se site, Se(4) is bonded in a distorted T-shaped geometry to two equivalent Er(1) and one P(1) atom. In the seventh Se site, Se(5) is bonded in an L-shaped geometry to one Er(1) and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_ErTl2P2Se7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.503
_cell_length_b   12.503
_cell_length_c   19.148
_cell_angle_alpha   62.131
_cell_angle_beta   62.131
_cell_angle_gamma   32.559
_symmetry_Int_Tables_number   1
_cell_volume   1406.951
_cell_formula_units_Z   4
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  0.891  0.786  0.241  1.0
  Er  Er1  1  0.214  0.109  0.259  1.0
  Er  Er2  1  0.109  0.214  0.759  1.0
  Er  Er3  1  0.786  0.891  0.741  1.0
  Tl  Tl4  1  0.834  0.821  0.019  1.0
  Tl  Tl5  1  0.179  0.166  0.481  1.0
  Tl  Tl6  1  0.166  0.179  0.981  1.0
  Tl  Tl7  1  0.821  0.834  0.519  1.0
  Tl  Tl8  1  0.541  0.466  0.128  1.0
  Tl  Tl9  1  0.534  0.459  0.372  1.0
  Tl  Tl10  1  0.459  0.534  0.872  1.0
  Tl  Tl11  1  0.466  0.541  0.628  1.0
  P  P12  1  0.682  0.658  0.358  1.0
  P  P13  1  0.342  0.318  0.142  1.0
  P  P14  1  0.318  0.342  0.642  1.0
  P  P15  1  0.658  0.682  0.858  1.0
  P  P16  1  0.986  0.920  0.307  1.0
  P  P17  1  0.080  0.014  0.193  1.0
  P  P18  1  0.014  0.080  0.693  1.0
  P  P19  1  0.920  0.986  0.807  1.0
  Se  Se20  1  0.005  0.947  0.402  1.0
  Se  Se21  1  0.053  0.995  0.098  1.0
  Se  Se22  1  0.995  0.053  0.598  1.0
  Se  Se23  1  0.947  0.005  0.902  1.0
  Se  Se24  1  0.192  0.614  0.302  1.0
  Se  Se25  1  0.386  0.808  0.198  1.0
  Se  Se26  1  0.808  0.386  0.698  1.0
  Se  Se27  1  0.614  0.192  0.802  1.0
  Se  Se28  1  0.169  0.626  0.091  1.0
  Se  Se29  1  0.374  0.831  0.409  1.0
  Se  Se30  1  0.831  0.374  0.909  1.0
  Se  Se31  1  0.626  0.169  0.591  1.0
  Se  Se32  1  0.225  0.326  0.272  1.0
  Se  Se33  1  0.674  0.775  0.228  1.0
  Se  Se34  1  0.775  0.674  0.728  1.0
  Se  Se35  1  0.326  0.225  0.772  1.0
  Se  Se36  1  0.764  0.711  0.404  1.0
  Se  Se37  1  0.289  0.236  0.096  1.0
  Se  Se38  1  0.236  0.289  0.596  1.0
  Se  Se39  1  0.711  0.764  0.904  1.0
  Se  Se40  1  0.880  0.339  0.389  1.0
  Se  Se41  1  0.661  0.120  0.111  1.0
  Se  Se42  1  0.120  0.661  0.611  1.0
  Se  Se43  1  0.339  0.880  0.889  1.0
  Se  Se44  1  0.888  0.314  0.198  1.0
  Se  Se45  1  0.686  0.112  0.302  1.0
  Se  Se46  1  0.112  0.686  0.802  1.0
  Se  Se47  1  0.314  0.888  0.698  1.0
[/CIF]
.