The crystal structure described by Tl2Cu2Hf3Se8 crystallizes in the monoclinic C2/m space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one Se(4), two equivalent Se(2), and three equivalent Se(3) atoms to form HfSe6 octahedra that share  a cornercorner with one Hf(2)Se6 octahedra, edges with four equivalent Hf(1)Se6 octahedra, and edges with two equivalent Cu(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. In the second Hf site, Hf(2) is bonded to two equivalent Se(4) and four equivalent Se(1) atoms to form HfSe6 octahedra that share corners with two equivalent Hf(1)Se6 octahedra, edges with two equivalent Hf(2)Se6 octahedra, and edges with four equivalent Cu(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. Cu(1) is bonded to one Se(1), one Se(2), and two equivalent Se(4) atoms to form distorted CuSe4 tetrahedra that share corners with two equivalent Cu(1)Se4 tetrahedra, edges with two equivalent Hf(1)Se6 octahedra, and edges with two equivalent Hf(2)Se6 octahedra. Tl(1) is bonded in a 7-coordinate geometry to one Se(3), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(4) atoms. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 3-coordinate geometry to two equivalent Hf(2), one Cu(1), and two equivalent Tl(1) atoms. In the second Se site, Se(2) is bonded in a 3-coordinate geometry to two equivalent Hf(1), one Cu(1), and two equivalent Tl(1) atoms. In the third Se site, Se(3) is bonded in a distorted T-shaped geometry to three equivalent Hf(1) and one Tl(1) atom. In the fourth Se site, Se(4) is bonded in a 4-coordinate geometry to one Hf(1), one Hf(2), two equivalent Cu(1), and two equivalent Tl(1) atoms. is represented by the CIF card [CIF]
data_Hf3Tl2(CuSe4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.707
_cell_length_b   7.707
_cell_length_c   14.503
_cell_angle_alpha   66.171
_cell_angle_beta   66.171
_cell_angle_gamma   28.711
_symmetry_Int_Tables_number   1
_cell_volume   376.148
_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
  Hf  Hf0  1  0.345  0.345  0.380  1.0
  Hf  Hf1  1  0.655  0.655  0.620  1.0
  Hf  Hf2  1  0.500  0.500  0.000  1.0
  Tl  Tl3  1  0.668  0.668  0.198  1.0
  Tl  Tl4  1  0.332  0.332  0.802  1.0
  Cu  Cu5  1  0.959  0.959  0.198  1.0
  Cu  Cu6  1  0.041  0.041  0.802  1.0
  Se  Se7  1  0.107  0.107  0.040  1.0
  Se  Se8  1  0.980  0.980  0.355  1.0
  Se  Se9  1  0.020  0.020  0.645  1.0
  Se  Se10  1  0.295  0.295  0.581  1.0
  Se  Se11  1  0.705  0.705  0.419  1.0
  Se  Se12  1  0.643  0.643  0.809  1.0
  Se  Se13  1  0.357  0.357  0.191  1.0
  Se  Se14  1  0.893  0.893  0.960  1.0
[/CIF]
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The crystal structure described by Tl2Cu2Hf3Se8 crystallizes in the monoclinic C2/m space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one Se(4), two equivalent Se(2), and three equivalent Se(3) atoms to form HfSe6 octahedra that share  a cornercorner with one Hf(2)Se6 octahedra, edges with four equivalent Hf(1)Se6 octahedra, and edges with two equivalent Cu(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. In the second Hf site, Hf(2) is bonded to two equivalent Se(4) and four equivalent Se(1) atoms to form HfSe6 octahedra that share corners with two equivalent Hf(1)Se6 octahedra, edges with two equivalent Hf(2)Se6 octahedra, and edges with four equivalent Cu(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. Cu(1) is bonded to one Se(1), one Se(2), and two equivalent Se(4) atoms to form distorted CuSe4 tetrahedra that share corners with two equivalent Cu(1)Se4 tetrahedra, edges with two equivalent Hf(1)Se6 octahedra, and edges with two equivalent Hf(2)Se6 octahedra. Tl(1) is bonded in a 7-coordinate geometry to one Se(3), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(4) atoms. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 3-coordinate geometry to two equivalent Hf(2), one Cu(1), and two equivalent Tl(1) atoms. In the second Se site, Se(2) is bonded in a 3-coordinate geometry to two equivalent Hf(1), one Cu(1), and two equivalent Tl(1) atoms. In the third Se site, Se(3) is bonded in a distorted T-shaped geometry to three equivalent Hf(1) and one Tl(1) atom. In the fourth Se site, Se(4) is bonded in a 4-coordinate geometry to one Hf(1), one Hf(2), two equivalent Cu(1), and two equivalent Tl(1) atoms. is represented by the CIF card [CIF]
data_Hf3Tl2(CuSe4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.707
_cell_length_b   7.707
_cell_length_c   14.503
_cell_angle_alpha   66.171
_cell_angle_beta   66.171
_cell_angle_gamma   28.711
_symmetry_Int_Tables_number   1
_cell_volume   376.148
_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
  Hf  Hf0  1  0.345  0.345  0.380  1.0
  Hf  Hf1  1  0.655  0.655  0.620  1.0
  Hf  Hf2  1  0.500  0.500  0.000  1.0
  Tl  Tl3  1  0.668  0.668  0.198  1.0
  Tl  Tl4  1  0.332  0.332  0.802  1.0
  Cu  Cu5  1  0.959  0.959  0.198  1.0
  Cu  Cu6  1  0.041  0.041  0.802  1.0
  Se  Se7  1  0.107  0.107  0.040  1.0
  Se  Se8  1  0.980  0.980  0.355  1.0
  Se  Se9  1  0.020  0.020  0.645  1.0
  Se  Se10  1  0.295  0.295  0.581  1.0
  Se  Se11  1  0.705  0.705  0.419  1.0
  Se  Se12  1  0.643  0.643  0.809  1.0
  Se  Se13  1  0.357  0.357  0.191  1.0
  Se  Se14  1  0.893  0.893  0.960  1.0
[/CIF]
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