The crystal structure described by KCu2NbSe4 crystallizes in the orthorhombic Ama2 space group. K(1) is bonded in a 9-coordinate geometry to one Se(1), four equivalent Se(2), and four equivalent Se(3) atoms. Nb(1) is bonded to one Se(1), one Se(3), and two equivalent Se(2) atoms to form distorted NbSe4 tetrahedra that share edges with two equivalent Cu(1)Se4 tetrahedra and 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(3), and two equivalent Se(2) atoms to form distorted CuSe4 tetrahedra that share corners with four equivalent Cu(2)Se4 tetrahedra and edges with two equivalent Nb(1)Se4 tetrahedra. In the second Cu site, Cu(2) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form distorted CuSe4 tetrahedra that share corners with two equivalent Cu(2)Se4 tetrahedra, corners with four equivalent Cu(1)Se4 tetrahedra, and edges with two equivalent Nb(1)Se4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted pentagonal planar geometry to one K(1), one Nb(1), one Cu(1), and two equivalent Cu(2) atoms. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to two equivalent K(1), one Nb(1), one Cu(1), and one Cu(2) atom. In the third Se site, Se(3) is bonded in a 4-coordinate geometry to four equivalent K(1), one Nb(1), and one Cu(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_KNb(CuSe2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.032
_cell_length_b   10.032
_cell_length_c   7.794
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   146.828
_symmetry_Int_Tables_number   1
_cell_volume   429.165
_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
  K  K0  1  0.924  0.556  0.250  1.0
  K  K1  1  0.556  0.924  0.750  1.0
  Nb  Nb2  1  0.609  0.391  0.750  1.0
  Nb  Nb3  1  0.391  0.609  0.250  1.0
  Cu  Cu4  1  0.107  0.894  0.750  1.0
  Cu  Cu5  1  0.894  0.107  0.250  1.0
  Cu  Cu6  1  0.484  0.484  0.500  1.0
  Cu  Cu7  1  0.484  0.484  0.000  1.0
  Se  Se8  1  0.749  0.743  0.750  1.0
  Se  Se9  1  0.144  0.358  0.506  1.0
  Se  Se10  1  0.541  0.962  0.250  1.0
  Se  Se11  1  0.743  0.749  0.250  1.0
  Se  Se12  1  0.962  0.541  0.750  1.0
  Se  Se13  1  0.144  0.358  0.994  1.0
  Se  Se14  1  0.358  0.144  0.006  1.0
  Se  Se15  1  0.358  0.144  0.494  1.0
[/CIF]
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The crystal structure described by KCu2NbSe4 crystallizes in the orthorhombic Ama2 space group. K(1) is bonded in a 9-coordinate geometry to one Se(1), four equivalent Se(2), and four equivalent Se(3) atoms. Nb(1) is bonded to one Se(1), one Se(3), and two equivalent Se(2) atoms to form distorted NbSe4 tetrahedra that share edges with two equivalent Cu(1)Se4 tetrahedra and 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(3), and two equivalent Se(2) atoms to form distorted CuSe4 tetrahedra that share corners with four equivalent Cu(2)Se4 tetrahedra and edges with two equivalent Nb(1)Se4 tetrahedra. In the second Cu site, Cu(2) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form distorted CuSe4 tetrahedra that share corners with two equivalent Cu(2)Se4 tetrahedra, corners with four equivalent Cu(1)Se4 tetrahedra, and edges with two equivalent Nb(1)Se4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted pentagonal planar geometry to one K(1), one Nb(1), one Cu(1), and two equivalent Cu(2) atoms. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to two equivalent K(1), one Nb(1), one Cu(1), and one Cu(2) atom. In the third Se site, Se(3) is bonded in a 4-coordinate geometry to four equivalent K(1), one Nb(1), and one Cu(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_KNb(CuSe2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.032
_cell_length_b   10.032
_cell_length_c   7.794
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   146.828
_symmetry_Int_Tables_number   1
_cell_volume   429.165
_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
  K  K0  1  0.924  0.556  0.250  1.0
  K  K1  1  0.556  0.924  0.750  1.0
  Nb  Nb2  1  0.609  0.391  0.750  1.0
  Nb  Nb3  1  0.391  0.609  0.250  1.0
  Cu  Cu4  1  0.107  0.894  0.750  1.0
  Cu  Cu5  1  0.894  0.107  0.250  1.0
  Cu  Cu6  1  0.484  0.484  0.500  1.0
  Cu  Cu7  1  0.484  0.484  0.000  1.0
  Se  Se8  1  0.749  0.743  0.750  1.0
  Se  Se9  1  0.144  0.358  0.506  1.0
  Se  Se10  1  0.541  0.962  0.250  1.0
  Se  Se11  1  0.743  0.749  0.250  1.0
  Se  Se12  1  0.962  0.541  0.750  1.0
  Se  Se13  1  0.144  0.358  0.994  1.0
  Se  Se14  1  0.358  0.144  0.006  1.0
  Se  Se15  1  0.358  0.144  0.494  1.0
[/CIF]
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