The compound described by Rb2TaCuSe4 crystallizes in the triclinic P1 space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(4), one Se(6), one Se(7), two equivalent Se(5), and two equivalent Se(8) atoms. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), one Se(5), one Se(8), two equivalent Se(6), and two equivalent Se(7) atoms. In the third Rb site, Rb(3) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), one Se(5), one Se(8), two equivalent Se(1), and two equivalent Se(4) atoms. In the fourth Rb site, Rb(4) is bonded in a 8-coordinate geometry to one Se(1), one Se(4), one Se(6), one Se(7), two equivalent Se(2), and two equivalent Se(3) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form distorted TaSe4 tetrahedra that share edges with two equivalent Cu(1)Se4 tetrahedra. In the second Ta site, Ta(2) is bonded to one Se(5), one Se(6), one Se(7), and one Se(8) atom to form distorted TaSe4 tetrahedra that share edges with two equivalent Cu(2)Se4 tetrahedra. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form distorted CuSe4 tetrahedra that share edges with two equivalent Ta(1)Se4 tetrahedra. In the second Cu site, Cu(2) is bonded to one Se(5), one Se(6), one Se(7), and one Se(8) atom to form distorted CuSe4 tetrahedra that share edges with two equivalent Ta(2)Se4 tetrahedra. There are eight inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(4), two equivalent Rb(3), one Ta(1), and one Cu(1) atom. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one Rb(2), one Rb(3), two equivalent Rb(4), one Ta(1), and one Cu(1) atom. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Rb(2), one Rb(3), two equivalent Rb(4), one Ta(1), and one Cu(1) atom. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(4), two equivalent Rb(3), one Ta(1), and one Cu(1) atom. In the fifth Se site, Se(5) is bonded in a 6-coordinate geometry to one Rb(2), one Rb(3), two equivalent Rb(1), one Ta(2), and one Cu(2) atom. In the sixth Se site, Se(6) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(4), two equivalent Rb(2), one Ta(2), and one Cu(2) atom. In the seventh Se site, Se(7) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(4), two equivalent Rb(2), one Ta(2), and one Cu(2) atom. In the eighth Se site, Se(8) is bonded in a 6-coordinate geometry to one Rb(2), one Rb(3), two equivalent Rb(1), one Ta(2), and one Cu(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Rb2TaCuSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   14.490
_cell_length_b   12.934
_cell_length_c   7.714
_cell_angle_alpha   85.161
_cell_angle_beta   62.804
_cell_angle_gamma   32.035
_symmetry_Int_Tables_number   1
_cell_volume   522.745
_cell_formula_units_Z   2
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
  Rb  Rb0  1  0.560  0.546  0.196  1.0
  Rb  Rb1  1  0.190  0.204  0.554  1.0
  Rb  Rb2  1  0.450  0.441  0.806  1.0
  Rb  Rb3  1  0.798  0.806  0.449  1.0
  Ta  Ta4  1  0.369  0.383  0.381  1.0
  Ta  Ta5  1  0.632  0.620  0.616  1.0
  Cu  Cu6  1  0.875  0.879  0.875  1.0
  Cu  Cu7  1  0.117  0.132  0.134  1.0
  Se  Se8  1  0.765  0.092  0.178  1.0
  Se  Se9  1  0.471  0.172  0.087  1.0
  Se  Se10  1  0.176  0.464  0.777  1.0
  Se  Se11  1  0.087  0.776  0.462  1.0
  Se  Se12  1  0.906  0.232  0.544  1.0
  Se  Se13  1  0.832  0.531  0.227  1.0
  Se  Se14  1  0.543  0.818  0.908  1.0
  Se  Se15  1  0.220  0.921  0.831  1.0
[/CIF]
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The compound described by Rb2TaCuSe4 crystallizes in the triclinic P1 space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(4), one Se(6), one Se(7), two equivalent Se(5), and two equivalent Se(8) atoms. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), one Se(5), one Se(8), two equivalent Se(6), and two equivalent Se(7) atoms. In the third Rb site, Rb(3) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), one Se(5), one Se(8), two equivalent Se(1), and two equivalent Se(4) atoms. In the fourth Rb site, Rb(4) is bonded in a 8-coordinate geometry to one Se(1), one Se(4), one Se(6), one Se(7), two equivalent Se(2), and two equivalent Se(3) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form distorted TaSe4 tetrahedra that share edges with two equivalent Cu(1)Se4 tetrahedra. In the second Ta site, Ta(2) is bonded to one Se(5), one Se(6), one Se(7), and one Se(8) atom to form distorted TaSe4 tetrahedra that share edges with two equivalent Cu(2)Se4 tetrahedra. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form distorted CuSe4 tetrahedra that share edges with two equivalent Ta(1)Se4 tetrahedra. In the second Cu site, Cu(2) is bonded to one Se(5), one Se(6), one Se(7), and one Se(8) atom to form distorted CuSe4 tetrahedra that share edges with two equivalent Ta(2)Se4 tetrahedra. There are eight inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(4), two equivalent Rb(3), one Ta(1), and one Cu(1) atom. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one Rb(2), one Rb(3), two equivalent Rb(4), one Ta(1), and one Cu(1) atom. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Rb(2), one Rb(3), two equivalent Rb(4), one Ta(1), and one Cu(1) atom. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(4), two equivalent Rb(3), one Ta(1), and one Cu(1) atom. In the fifth Se site, Se(5) is bonded in a 6-coordinate geometry to one Rb(2), one Rb(3), two equivalent Rb(1), one Ta(2), and one Cu(2) atom. In the sixth Se site, Se(6) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(4), two equivalent Rb(2), one Ta(2), and one Cu(2) atom. In the seventh Se site, Se(7) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(4), two equivalent Rb(2), one Ta(2), and one Cu(2) atom. In the eighth Se site, Se(8) is bonded in a 6-coordinate geometry to one Rb(2), one Rb(3), two equivalent Rb(1), one Ta(2), and one Cu(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Rb2TaCuSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   14.490
_cell_length_b   12.934
_cell_length_c   7.714
_cell_angle_alpha   85.161
_cell_angle_beta   62.804
_cell_angle_gamma   32.035
_symmetry_Int_Tables_number   1
_cell_volume   522.745
_cell_formula_units_Z   2
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
  Rb  Rb0  1  0.560  0.546  0.196  1.0
  Rb  Rb1  1  0.190  0.204  0.554  1.0
  Rb  Rb2  1  0.450  0.441  0.806  1.0
  Rb  Rb3  1  0.798  0.806  0.449  1.0
  Ta  Ta4  1  0.369  0.383  0.381  1.0
  Ta  Ta5  1  0.632  0.620  0.616  1.0
  Cu  Cu6  1  0.875  0.879  0.875  1.0
  Cu  Cu7  1  0.117  0.132  0.134  1.0
  Se  Se8  1  0.765  0.092  0.178  1.0
  Se  Se9  1  0.471  0.172  0.087  1.0
  Se  Se10  1  0.176  0.464  0.777  1.0
  Se  Se11  1  0.087  0.776  0.462  1.0
  Se  Se12  1  0.906  0.232  0.544  1.0
  Se  Se13  1  0.832  0.531  0.227  1.0
  Se  Se14  1  0.543  0.818  0.908  1.0
  Se  Se15  1  0.220  0.921  0.831  1.0
[/CIF]
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