The compound described by CoCr2Se4 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 distorted CrSe6 octahedra that share corners with six equivalent Co(1)Se6 octahedra, edges with six equivalent Cr(1)Se6 octahedra, and  a faceface with one Co(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. Co(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form CoSe6 octahedra that share corners with twelve equivalent Cr(1)Se6 octahedra, edges with two equivalent Co(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 in a rectangular see-saw-like geometry to three equivalent Cr(1) and one Co(1) atom. In the second Se site, Se(1) is bonded to three equivalent Cr(1) and two equivalent Co(1) atoms to form a mixture of distorted corner and edge-sharing SeCr3Co2 square pyramids. is represented by the CIF card [CIF]
data_Cr2CoSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.656
_cell_length_b   6.363
_cell_length_c   6.562
_cell_angle_alpha   117.631
_cell_angle_beta   106.177
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   128.384
_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  0.719  0.479  1.0
  Cr  Cr1  1  0.260  0.281  0.521  1.0
  Co  Co2  1  0.000  0.000  0.000  1.0
  Se  Se3  1  0.628  0.972  0.257  1.0
  Se  Se4  1  0.372  0.028  0.743  1.0
  Se  Se5  1  0.885  0.557  0.770  1.0
  Se  Se6  1  0.115  0.443  0.230  1.0
[/CIF]
.
The compound described by CoCr2Se4 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 distorted CrSe6 octahedra that share corners with six equivalent Co(1)Se6 octahedra, edges with six equivalent Cr(1)Se6 octahedra, and  a faceface with one Co(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. Co(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form CoSe6 octahedra that share corners with twelve equivalent Cr(1)Se6 octahedra, edges with two equivalent Co(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 in a rectangular see-saw-like geometry to three equivalent Cr(1) and one Co(1) atom. In the second Se site, Se(1) is bonded to three equivalent Cr(1) and two equivalent Co(1) atoms to form a mixture of distorted corner and edge-sharing SeCr3Co2 square pyramids. is represented by the CIF card [CIF]
data_Cr2CoSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.656
_cell_length_b   6.363
_cell_length_c   6.562
_cell_angle_alpha   117.631
_cell_angle_beta   106.177
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   128.384
_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  0.719  0.479  1.0
  Cr  Cr1  1  0.260  0.281  0.521  1.0
  Co  Co2  1  0.000  0.000  0.000  1.0
  Se  Se3  1  0.628  0.972  0.257  1.0
  Se  Se4  1  0.372  0.028  0.743  1.0
  Se  Se5  1  0.885  0.557  0.770  1.0
  Se  Se6  1  0.115  0.443  0.230  1.0
[/CIF]
.