The crystal structure described by Nb4CrSe8 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to six equivalent Se(1) atoms to form NbSe6 octahedra that share edges with six equivalent Nb(2)Se6 octahedra and faces with two equivalent Cr(1)Se6 pentagonal pyramids. In the second Nb site, Nb(2) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form NbSe6 octahedra that share corners with four equivalent Cr(1)Se6 pentagonal pyramids, edges with two equivalent Nb(1)Se6 octahedra, and edges with four equivalent Nb(2)Se6 octahedra. Cr(1) is bonded to six equivalent Se(1) atoms to form distorted CrSe6 pentagonal pyramids that share corners with twelve equivalent Nb(2)Se6 octahedra and faces with two equivalent Nb(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Nb(1), two equivalent Nb(2), and one Cr(1) atom to form a mixture of edge and corner-sharing SeNb3Cr trigonal pyramids. In the second Se site, Se(2) is bonded in a distorted T-shaped geometry to three equivalent Nb(2) atoms. is represented by the CIF card [CIF]
data_Nb4CrSe8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.979
_cell_length_b   6.979
_cell_length_c   13.836
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   583.622
_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
  Nb  Nb0  1  0.000  0.000  0.000  1.0
  Nb  Nb1  1  0.500  0.000  0.500  1.0
  Nb  Nb2  1  0.500  0.500  0.000  1.0
  Nb  Nb3  1  0.000  0.500  0.000  1.0
  Nb  Nb4  1  0.000  0.500  0.500  1.0
  Nb  Nb5  1  0.500  0.500  0.500  1.0
  Nb  Nb6  1  0.500  0.000  0.000  1.0
  Nb  Nb7  1  0.000  0.000  0.500  1.0
  Cr  Cr8  1  0.000  0.000  0.250  1.0
  Cr  Cr9  1  0.000  0.000  0.750  1.0
  Se  Se10  1  0.833  0.167  0.877  1.0
  Se  Se11  1  0.167  0.833  0.377  1.0
  Se  Se12  1  0.167  0.335  0.377  1.0
  Se  Se13  1  0.665  0.833  0.377  1.0
  Se  Se14  1  0.335  0.167  0.877  1.0
  Se  Se15  1  0.833  0.665  0.623  1.0
  Se  Se16  1  0.333  0.667  0.879  1.0
  Se  Se17  1  0.833  0.665  0.877  1.0
  Se  Se18  1  0.333  0.667  0.621  1.0
  Se  Se19  1  0.667  0.333  0.121  1.0
  Se  Se20  1  0.667  0.333  0.379  1.0
  Se  Se21  1  0.167  0.335  0.123  1.0
  Se  Se22  1  0.665  0.833  0.123  1.0
  Se  Se23  1  0.833  0.167  0.623  1.0
  Se  Se24  1  0.335  0.167  0.623  1.0
  Se  Se25  1  0.167  0.833  0.123  1.0
[/CIF]
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The crystal structure described by Nb4CrSe8 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to six equivalent Se(1) atoms to form NbSe6 octahedra that share edges with six equivalent Nb(2)Se6 octahedra and faces with two equivalent Cr(1)Se6 pentagonal pyramids. In the second Nb site, Nb(2) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form NbSe6 octahedra that share corners with four equivalent Cr(1)Se6 pentagonal pyramids, edges with two equivalent Nb(1)Se6 octahedra, and edges with four equivalent Nb(2)Se6 octahedra. Cr(1) is bonded to six equivalent Se(1) atoms to form distorted CrSe6 pentagonal pyramids that share corners with twelve equivalent Nb(2)Se6 octahedra and faces with two equivalent Nb(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Nb(1), two equivalent Nb(2), and one Cr(1) atom to form a mixture of edge and corner-sharing SeNb3Cr trigonal pyramids. In the second Se site, Se(2) is bonded in a distorted T-shaped geometry to three equivalent Nb(2) atoms. is represented by the CIF card [CIF]
data_Nb4CrSe8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.979
_cell_length_b   6.979
_cell_length_c   13.836
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   583.622
_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
  Nb  Nb0  1  0.000  0.000  0.000  1.0
  Nb  Nb1  1  0.500  0.000  0.500  1.0
  Nb  Nb2  1  0.500  0.500  0.000  1.0
  Nb  Nb3  1  0.000  0.500  0.000  1.0
  Nb  Nb4  1  0.000  0.500  0.500  1.0
  Nb  Nb5  1  0.500  0.500  0.500  1.0
  Nb  Nb6  1  0.500  0.000  0.000  1.0
  Nb  Nb7  1  0.000  0.000  0.500  1.0
  Cr  Cr8  1  0.000  0.000  0.250  1.0
  Cr  Cr9  1  0.000  0.000  0.750  1.0
  Se  Se10  1  0.833  0.167  0.877  1.0
  Se  Se11  1  0.167  0.833  0.377  1.0
  Se  Se12  1  0.167  0.335  0.377  1.0
  Se  Se13  1  0.665  0.833  0.377  1.0
  Se  Se14  1  0.335  0.167  0.877  1.0
  Se  Se15  1  0.833  0.665  0.623  1.0
  Se  Se16  1  0.333  0.667  0.879  1.0
  Se  Se17  1  0.833  0.665  0.877  1.0
  Se  Se18  1  0.333  0.667  0.621  1.0
  Se  Se19  1  0.667  0.333  0.121  1.0
  Se  Se20  1  0.667  0.333  0.379  1.0
  Se  Se21  1  0.167  0.335  0.123  1.0
  Se  Se22  1  0.665  0.833  0.123  1.0
  Se  Se23  1  0.833  0.167  0.623  1.0
  Se  Se24  1  0.335  0.167  0.623  1.0
  Se  Se25  1  0.167  0.833  0.123  1.0
[/CIF]
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