The material structure described by NiCr2Se4 crystallizes in the monoclinic C2/m space group. Cr(1) is bonded to three equivalent Se(1) and three equivalent Se(2) atoms to form CrSe6 octahedra that share corners with six equivalent Ni(1)Se6 octahedra, edges with six equivalent Cr(1)Se6 octahedra, and  a faceface with one Ni(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. Ni(1) is bonded to two equivalent Se(1) and four equivalent Se(2) atoms to form NiSe6 octahedra that share corners with twelve equivalent Cr(1)Se6 octahedra, edges with two equivalent Ni(1)Se6 octahedra, and faces with two equivalent Cr(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded to three equivalent Cr(1) and two equivalent Ni(1) atoms to form a mixture of distorted corner and edge-sharing SeCr3Ni2 trigonal bipyramids. In the second Se site, Se(1) is bonded in a rectangular see-saw-like geometry to three equivalent Cr(1) and one Ni(1) atom. is represented by the CIF card [CIF]
data_Cr2NiSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.586
_cell_length_b   6.586
_cell_length_c   6.294
_cell_angle_alpha   63.670
_cell_angle_beta   63.670
_cell_angle_gamma   31.783
_symmetry_Int_Tables_number   1
_cell_volume   127.605
_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
  Cr  Cr0  1  0.740  0.740  0.281  1.0
  Cr  Cr1  1  0.260  0.260  0.719  1.0
  Ni  Ni2  1  0.000  0.000  0.000  1.0
  Se  Se3  1  0.884  0.884  0.448  1.0
  Se  Se4  1  0.116  0.116  0.552  1.0
  Se  Se5  1  0.632  0.632  0.025  1.0
  Se  Se6  1  0.368  0.368  0.975  1.0
[/CIF]
.
The material structure described by NiCr2Se4 crystallizes in the monoclinic C2/m space group. Cr(1) is bonded to three equivalent Se(1) and three equivalent Se(2) atoms to form CrSe6 octahedra that share corners with six equivalent Ni(1)Se6 octahedra, edges with six equivalent Cr(1)Se6 octahedra, and  a faceface with one Ni(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. Ni(1) is bonded to two equivalent Se(1) and four equivalent Se(2) atoms to form NiSe6 octahedra that share corners with twelve equivalent Cr(1)Se6 octahedra, edges with two equivalent Ni(1)Se6 octahedra, and faces with two equivalent Cr(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded to three equivalent Cr(1) and two equivalent Ni(1) atoms to form a mixture of distorted corner and edge-sharing SeCr3Ni2 trigonal bipyramids. In the second Se site, Se(1) is bonded in a rectangular see-saw-like geometry to three equivalent Cr(1) and one Ni(1) atom. is represented by the CIF card [CIF]
data_Cr2NiSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.586
_cell_length_b   6.586
_cell_length_c   6.294
_cell_angle_alpha   63.670
_cell_angle_beta   63.670
_cell_angle_gamma   31.783
_symmetry_Int_Tables_number   1
_cell_volume   127.605
_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
  Cr  Cr0  1  0.740  0.740  0.281  1.0
  Cr  Cr1  1  0.260  0.260  0.719  1.0
  Ni  Ni2  1  0.000  0.000  0.000  1.0
  Se  Se3  1  0.884  0.884  0.448  1.0
  Se  Se4  1  0.116  0.116  0.552  1.0
  Se  Se5  1  0.632  0.632  0.025  1.0
  Se  Se6  1  0.368  0.368  0.975  1.0
[/CIF]
.