The material structure described by Cs5FeO4 crystallizes in the monoclinic P2_1/c space group. There are five inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Cs site, Cs(2) is bonded in a 4-coordinate geometry to one O(2), one O(4), and two equivalent O(1) atoms. In the third Cs site, Cs(3) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form distorted CsO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Cs(3)O4 tetrahedra, and  an edgeedge with one Fe(1)O4 tetrahedra. In the fourth Cs site, Cs(4) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(4), and two equivalent O(2) atoms. In the fifth Cs site, Cs(5) is bonded in a 3-coordinate geometry to one O(1), one O(3), and one O(4) atom. Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form FeO4 tetrahedra that share corners with two equivalent Cs(3)O4 tetrahedra and  an edgeedge with one Cs(3)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(3) is bonded in a 1-coordinate geometry to one Cs(5), two equivalent Cs(1), two equivalent Cs(3), and one Fe(1) atom. In the second O site, O(4) is bonded in a distorted single-bond geometry to one Cs(2), one Cs(3), one Cs(4), one Cs(5), two equivalent Cs(1), and one Fe(1) atom. In the third O site, O(1) is bonded to one Cs(3), one Cs(4), one Cs(5), two equivalent Cs(2), and one Fe(1) atom to form distorted corner-sharing OCs5Fe octahedra. The corner-sharing octahedral tilt angles are 61°. In the fourth O site, O(2) is bonded in a 6-coordinate geometry to one Cs(2), two equivalent Cs(1), two equivalent Cs(4), and one Fe(1) atom. is represented by the CIF file [CIF]
data_Cs5FeO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.792
_cell_length_b   7.319
_cell_length_c   11.381
_cell_angle_alpha   80.950
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1052.252
_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
  Cs  Cs0  1  0.703  0.010  0.234  1.0
  Cs  Cs1  1  0.203  0.490  0.766  1.0
  Cs  Cs2  1  0.297  0.990  0.766  1.0
  Cs  Cs3  1  0.797  0.510  0.234  1.0
  Cs  Cs4  1  0.176  0.165  0.150  1.0
  Cs  Cs5  1  0.676  0.335  0.850  1.0
  Cs  Cs6  1  0.824  0.835  0.850  1.0
  Cs  Cs7  1  0.324  0.665  0.150  1.0
  Cs  Cs8  1  0.070  0.451  0.367  1.0
  Cs  Cs9  1  0.570  0.049  0.633  1.0
  Cs  Cs10  1  0.930  0.549  0.633  1.0
  Cs  Cs11  1  0.430  0.951  0.367  1.0
  Cs  Cs12  1  0.924  0.241  0.008  1.0
  Cs  Cs13  1  0.424  0.259  0.992  1.0
  Cs  Cs14  1  0.076  0.759  0.992  1.0
  Cs  Cs15  1  0.576  0.741  0.008  1.0
  Cs  Cs16  1  0.864  0.074  0.505  1.0
  Cs  Cs17  1  0.364  0.426  0.495  1.0
  Cs  Cs18  1  0.136  0.926  0.495  1.0
  Cs  Cs19  1  0.636  0.574  0.505  1.0
  Fe  Fe20  1  0.532  0.388  0.254  1.0
  Fe  Fe21  1  0.032  0.112  0.746  1.0
  Fe  Fe22  1  0.468  0.612  0.746  1.0
  Fe  Fe23  1  0.968  0.888  0.254  1.0
  O  O24  1  0.889  0.184  0.760  1.0
  O  O25  1  0.389  0.316  0.240  1.0
  O  O26  1  0.111  0.816  0.240  1.0
  O  O27  1  0.611  0.684  0.760  1.0
  O  O28  1  0.607  0.355  0.112  1.0
  O  O29  1  0.107  0.145  0.888  1.0
  O  O30  1  0.393  0.645  0.888  1.0
  O  O31  1  0.893  0.855  0.112  1.0
  O  O32  1  0.594  0.245  0.389  1.0
  O  O33  1  0.094  0.255  0.611  1.0
  O  O34  1  0.406  0.755  0.611  1.0
  O  O35  1  0.906  0.745  0.389  1.0
  O  O36  1  0.967  0.142  0.272  1.0
  O  O37  1  0.467  0.358  0.728  1.0
  O  O38  1  0.033  0.858  0.728  1.0
  O  O39  1  0.533  0.642  0.272  1.0
[/CIF]
.
The material structure described by Cs5FeO4 crystallizes in the monoclinic P2_1/c space group. There are five inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Cs site, Cs(2) is bonded in a 4-coordinate geometry to one O(2), one O(4), and two equivalent O(1) atoms. In the third Cs site, Cs(3) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form distorted CsO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Cs(3)O4 tetrahedra, and  an edgeedge with one Fe(1)O4 tetrahedra. In the fourth Cs site, Cs(4) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(4), and two equivalent O(2) atoms. In the fifth Cs site, Cs(5) is bonded in a 3-coordinate geometry to one O(1), one O(3), and one O(4) atom. Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form FeO4 tetrahedra that share corners with two equivalent Cs(3)O4 tetrahedra and  an edgeedge with one Cs(3)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(3) is bonded in a 1-coordinate geometry to one Cs(5), two equivalent Cs(1), two equivalent Cs(3), and one Fe(1) atom. In the second O site, O(4) is bonded in a distorted single-bond geometry to one Cs(2), one Cs(3), one Cs(4), one Cs(5), two equivalent Cs(1), and one Fe(1) atom. In the third O site, O(1) is bonded to one Cs(3), one Cs(4), one Cs(5), two equivalent Cs(2), and one Fe(1) atom to form distorted corner-sharing OCs5Fe octahedra. The corner-sharing octahedral tilt angles are 61°. In the fourth O site, O(2) is bonded in a 6-coordinate geometry to one Cs(2), two equivalent Cs(1), two equivalent Cs(4), and one Fe(1) atom. is represented by the CIF file [CIF]
data_Cs5FeO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.792
_cell_length_b   7.319
_cell_length_c   11.381
_cell_angle_alpha   80.950
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1052.252
_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
  Cs  Cs0  1  0.703  0.010  0.234  1.0
  Cs  Cs1  1  0.203  0.490  0.766  1.0
  Cs  Cs2  1  0.297  0.990  0.766  1.0
  Cs  Cs3  1  0.797  0.510  0.234  1.0
  Cs  Cs4  1  0.176  0.165  0.150  1.0
  Cs  Cs5  1  0.676  0.335  0.850  1.0
  Cs  Cs6  1  0.824  0.835  0.850  1.0
  Cs  Cs7  1  0.324  0.665  0.150  1.0
  Cs  Cs8  1  0.070  0.451  0.367  1.0
  Cs  Cs9  1  0.570  0.049  0.633  1.0
  Cs  Cs10  1  0.930  0.549  0.633  1.0
  Cs  Cs11  1  0.430  0.951  0.367  1.0
  Cs  Cs12  1  0.924  0.241  0.008  1.0
  Cs  Cs13  1  0.424  0.259  0.992  1.0
  Cs  Cs14  1  0.076  0.759  0.992  1.0
  Cs  Cs15  1  0.576  0.741  0.008  1.0
  Cs  Cs16  1  0.864  0.074  0.505  1.0
  Cs  Cs17  1  0.364  0.426  0.495  1.0
  Cs  Cs18  1  0.136  0.926  0.495  1.0
  Cs  Cs19  1  0.636  0.574  0.505  1.0
  Fe  Fe20  1  0.532  0.388  0.254  1.0
  Fe  Fe21  1  0.032  0.112  0.746  1.0
  Fe  Fe22  1  0.468  0.612  0.746  1.0
  Fe  Fe23  1  0.968  0.888  0.254  1.0
  O  O24  1  0.889  0.184  0.760  1.0
  O  O25  1  0.389  0.316  0.240  1.0
  O  O26  1  0.111  0.816  0.240  1.0
  O  O27  1  0.611  0.684  0.760  1.0
  O  O28  1  0.607  0.355  0.112  1.0
  O  O29  1  0.107  0.145  0.888  1.0
  O  O30  1  0.393  0.645  0.888  1.0
  O  O31  1  0.893  0.855  0.112  1.0
  O  O32  1  0.594  0.245  0.389  1.0
  O  O33  1  0.094  0.255  0.611  1.0
  O  O34  1  0.406  0.755  0.611  1.0
  O  O35  1  0.906  0.745  0.389  1.0
  O  O36  1  0.967  0.142  0.272  1.0
  O  O37  1  0.467  0.358  0.728  1.0
  O  O38  1  0.033  0.858  0.728  1.0
  O  O39  1  0.533  0.642  0.272  1.0
[/CIF]
.