The compound described by CaFeO2 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted CaO5 trigonal bipyramids that share corners with four equivalent Ca(2)O4 tetrahedra, corners with two equivalent Fe(2)O5 trigonal bipyramids, edges with two equivalent Ca(1)O5 trigonal bipyramids, and  a faceface with one Fe(2)O5 trigonal bipyramid. In the second Ca site, Ca(2) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form CaO4 tetrahedra that share corners with two equivalent Ca(2)O4 tetrahedra, corners with four equivalent Ca(1)O5 trigonal bipyramids, corners with four equivalent Fe(2)O5 trigonal bipyramids, and  an edgeedge with one Fe(2)O5 trigonal bipyramid. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(3) atoms. In the second Fe site, Fe(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted FeO5 trigonal bipyramids that share corners with four equivalent Ca(2)O4 tetrahedra, corners with two equivalent Ca(1)O5 trigonal bipyramids,  an edgeedge with one Ca(2)O4 tetrahedra, edges with two equivalent Fe(2)O5 trigonal bipyramids, and  a faceface with one Ca(1)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms to form OCaFe3 tetrahedra that share corners with two equivalent O(1)CaFe3 tetrahedra, corners with four equivalent O(3)Ca3Fe2 trigonal bipyramids,  an edgeedge with one O(3)Ca3Fe2 trigonal bipyramid, and edges with two equivalent O(4)Ca3Fe2 trigonal bipyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(2) and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded to one Ca(2), two equivalent Ca(1), and two equivalent Fe(1) atoms to form distorted OCa3Fe2 trigonal bipyramids that share corners with four equivalent O(1)CaFe3 tetrahedra, corners with three equivalent O(4)Ca3Fe2 trigonal bipyramids,  an edgeedge with one O(1)CaFe3 tetrahedra,  an edgeedge with one O(4)Ca3Fe2 trigonal bipyramid, and edges with two equivalent O(3)Ca3Fe2 trigonal bipyramids. In the fourth O site, O(4) is bonded to one Ca(2), two equivalent Ca(1), and two equivalent Fe(2) atoms to form distorted OCa3Fe2 trigonal bipyramids that share corners with three equivalent O(3)Ca3Fe2 trigonal bipyramids, edges with two equivalent O(1)CaFe3 tetrahedra,  an edgeedge with one O(3)Ca3Fe2 trigonal bipyramid, and edges with two equivalent O(4)Ca3Fe2 trigonal bipyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_CaFeO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.135
_cell_length_b   8.883
_cell_length_c   9.267
_cell_angle_alpha   90.801
_cell_angle_beta   98.653
_cell_angle_gamma   99.264
_symmetry_Int_Tables_number   1
_cell_volume   251.581
_cell_formula_units_Z   4
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
  Ca  Ca0  1  0.595  0.234  0.931  1.0
  Ca  Ca1  1  0.405  0.766  0.069  1.0
  Ca  Ca2  1  0.224  0.123  0.311  1.0
  Ca  Ca3  1  0.776  0.877  0.689  1.0
  Fe  Fe4  1  0.171  0.550  0.796  1.0
  Fe  Fe5  1  0.410  0.209  0.625  1.0
  Fe  Fe6  1  0.590  0.791  0.375  1.0
  Fe  Fe7  1  0.829  0.450  0.204  1.0
  O  O8  1  0.412  0.588  0.243  1.0
  O  O9  1  0.176  0.818  0.523  1.0
  O  O10  1  0.824  0.182  0.477  1.0
  O  O11  1  0.588  0.412  0.757  1.0
  O  O12  1  0.787  0.705  0.875  1.0
  O  O13  1  0.973  0.115  0.783  1.0
  O  O14  1  0.213  0.295  0.125  1.0
  O  O15  1  0.027  0.885  0.217  1.0
[/CIF]
.
The compound described by CaFeO2 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted CaO5 trigonal bipyramids that share corners with four equivalent Ca(2)O4 tetrahedra, corners with two equivalent Fe(2)O5 trigonal bipyramids, edges with two equivalent Ca(1)O5 trigonal bipyramids, and  a faceface with one Fe(2)O5 trigonal bipyramid. In the second Ca site, Ca(2) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form CaO4 tetrahedra that share corners with two equivalent Ca(2)O4 tetrahedra, corners with four equivalent Ca(1)O5 trigonal bipyramids, corners with four equivalent Fe(2)O5 trigonal bipyramids, and  an edgeedge with one Fe(2)O5 trigonal bipyramid. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(3) atoms. In the second Fe site, Fe(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted FeO5 trigonal bipyramids that share corners with four equivalent Ca(2)O4 tetrahedra, corners with two equivalent Ca(1)O5 trigonal bipyramids,  an edgeedge with one Ca(2)O4 tetrahedra, edges with two equivalent Fe(2)O5 trigonal bipyramids, and  a faceface with one Ca(1)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms to form OCaFe3 tetrahedra that share corners with two equivalent O(1)CaFe3 tetrahedra, corners with four equivalent O(3)Ca3Fe2 trigonal bipyramids,  an edgeedge with one O(3)Ca3Fe2 trigonal bipyramid, and edges with two equivalent O(4)Ca3Fe2 trigonal bipyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(2) and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded to one Ca(2), two equivalent Ca(1), and two equivalent Fe(1) atoms to form distorted OCa3Fe2 trigonal bipyramids that share corners with four equivalent O(1)CaFe3 tetrahedra, corners with three equivalent O(4)Ca3Fe2 trigonal bipyramids,  an edgeedge with one O(1)CaFe3 tetrahedra,  an edgeedge with one O(4)Ca3Fe2 trigonal bipyramid, and edges with two equivalent O(3)Ca3Fe2 trigonal bipyramids. In the fourth O site, O(4) is bonded to one Ca(2), two equivalent Ca(1), and two equivalent Fe(2) atoms to form distorted OCa3Fe2 trigonal bipyramids that share corners with three equivalent O(3)Ca3Fe2 trigonal bipyramids, edges with two equivalent O(1)CaFe3 tetrahedra,  an edgeedge with one O(3)Ca3Fe2 trigonal bipyramid, and edges with two equivalent O(4)Ca3Fe2 trigonal bipyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_CaFeO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.135
_cell_length_b   8.883
_cell_length_c   9.267
_cell_angle_alpha   90.801
_cell_angle_beta   98.653
_cell_angle_gamma   99.264
_symmetry_Int_Tables_number   1
_cell_volume   251.581
_cell_formula_units_Z   4
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
  Ca  Ca0  1  0.595  0.234  0.931  1.0
  Ca  Ca1  1  0.405  0.766  0.069  1.0
  Ca  Ca2  1  0.224  0.123  0.311  1.0
  Ca  Ca3  1  0.776  0.877  0.689  1.0
  Fe  Fe4  1  0.171  0.550  0.796  1.0
  Fe  Fe5  1  0.410  0.209  0.625  1.0
  Fe  Fe6  1  0.590  0.791  0.375  1.0
  Fe  Fe7  1  0.829  0.450  0.204  1.0
  O  O8  1  0.412  0.588  0.243  1.0
  O  O9  1  0.176  0.818  0.523  1.0
  O  O10  1  0.824  0.182  0.477  1.0
  O  O11  1  0.588  0.412  0.757  1.0
  O  O12  1  0.787  0.705  0.875  1.0
  O  O13  1  0.973  0.115  0.783  1.0
  O  O14  1  0.213  0.295  0.125  1.0
  O  O15  1  0.027  0.885  0.217  1.0
[/CIF]
.