The compound described by Na5Co2O5 crystallizes in the monoclinic C2/c space group. There are five inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded to one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent Co(1)O4 tetrahedra, corners with two equivalent Na(4)O4 trigonal pyramids, corners with two equivalent Na(5)O4 trigonal pyramids,  an edgeedge with one Co(1)O4 tetrahedra, edges with two equivalent Na(2)O5 trigonal bipyramids, and edges with two equivalent Na(5)O4 trigonal pyramids. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(3), one O(4), and two equivalent O(5) atoms. In the fourth Na site, Na(4) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form NaO4 trigonal pyramids that share corners with two equivalent Co(1)O4 tetrahedra, corners with two equivalent Na(2)O5 trigonal bipyramids, corners with two equivalent Na(5)O4 trigonal pyramids, and  an edgeedge with one Na(4)O4 trigonal pyramid. In the fifth Na site, Na(5) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form distorted NaO4 trigonal pyramids that share corners with two equivalent Co(1)O4 tetrahedra, corners with two equivalent Na(2)O5 trigonal bipyramids, corners with two equivalent Na(4)O4 trigonal pyramids, edges with two equivalent Na(2)O5 trigonal bipyramids, and  an edgeedge with one Na(5)O4 trigonal pyramid. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), and two equivalent O(5) atoms to form distorted CoO4 tetrahedra that share corners with two equivalent Na(2)O5 trigonal bipyramids, corners with two equivalent Na(4)O4 trigonal pyramids, corners with two equivalent Na(5)O4 trigonal pyramids,  an edgeedge with one Co(1)O4 tetrahedra, and  an edgeedge with one Na(2)O5 trigonal bipyramid. In the second Co site, Co(2) is bonded in a distorted trigonal planar geometry to one O(2), one O(3), and one O(4) atom. There are five inequivalent O sites. In the first O site, O(5) is bonded to one Na(1), one Na(2), two equivalent Na(3), and two equivalent Co(1) atoms to form distorted ONa4Co2 octahedra that share corners with four equivalent O(3)Na5Co octahedra, edges with two equivalent O(5)Na4Co2 octahedra, and edges with two equivalent O(4)Na5Co octahedra. The corner-sharing octahedral tilt angles range from 42-67°. In the second O site, O(1) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(2), two equivalent Na(5), and one Co(1) atom. In the third O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(4), one Co(1), and one Co(2) atom. In the fourth O site, O(3) is bonded to one Na(3), one Na(4), one Na(5), two equivalent Na(1), and one Co(2) atom to form distorted ONa5Co octahedra that share corners with four equivalent O(5)Na4Co2 octahedra, corners with four equivalent O(4)Na5Co octahedra, and  an edgeedge with one O(3)Na5Co octahedra. The corner-sharing octahedral tilt angles range from 42-67°. In the fifth O site, O(4) is bonded to one Na(3), one Na(4), one Na(5), two equivalent Na(2), and one Co(2) atom to form ONa5Co octahedra that share corners with four equivalent O(3)Na5Co octahedra,  an edgeedge with one O(4)Na5Co octahedra, and edges with two equivalent O(5)Na4Co2 octahedra. The corner-sharing octahedral tilt angles range from 42-55°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na5Co2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.555
_cell_length_b   8.555
_cell_length_c   11.500
_cell_angle_alpha   77.102
_cell_angle_beta   77.102
_cell_angle_gamma   57.048
_symmetry_Int_Tables_number   1
_cell_volume   683.143
_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
  Na  Na0  1  0.329  1.000  0.960  1.0
  Na  Na1  1  0.621  0.403  0.377  1.0
  Na  Na2  1  1.000  0.329  0.460  1.0
  Na  Na3  1  0.597  0.379  0.123  1.0
  Na  Na4  1  0.403  0.621  0.877  1.0
  Na  Na5  1  0.989  0.798  0.810  1.0
  Na  Na6  1  0.379  0.597  0.623  1.0
  Na  Na7  1  0.798  0.989  0.310  1.0
  Na  Na8  1  0.603  0.794  0.483  1.0
  Na  Na9  1  0.671  0.000  0.040  1.0
  Na  Na10  1  0.434  0.778  0.212  1.0
  Na  Na11  1  0.397  0.206  0.517  1.0
  Na  Na12  1  0.202  0.011  0.690  1.0
  Na  Na13  1  0.206  0.397  0.017  1.0
  Na  Na14  1  0.222  0.566  0.288  1.0
  Na  Na15  1  0.794  0.603  0.983  1.0
  Na  Na16  1  0.000  0.671  0.540  1.0
  Na  Na17  1  0.566  0.222  0.788  1.0
  Na  Na18  1  0.011  0.202  0.190  1.0
  Na  Na19  1  0.778  0.434  0.712  1.0
  Co  Co20  1  0.184  0.915  0.443  1.0
  Co  Co21  1  0.386  0.144  0.268  1.0
  Co  Co22  1  0.085  0.816  0.057  1.0
  Co  Co23  1  0.856  0.614  0.232  1.0
  Co  Co24  1  0.816  0.085  0.557  1.0
  Co  Co25  1  0.915  0.184  0.943  1.0
  Co  Co26  1  0.144  0.386  0.768  1.0
  Co  Co27  1  0.614  0.856  0.732  1.0
  O  O28  1  0.323  0.684  0.090  1.0
  O  O29  1  0.307  0.043  0.429  1.0
  O  O30  1  0.316  0.677  0.410  1.0
  O  O31  1  0.905  0.648  0.366  1.0
  O  O32  1  0.095  0.352  0.634  1.0
  O  O33  1  0.648  0.905  0.866  1.0
  O  O34  1  0.264  0.485  0.807  1.0
  O  O35  1  0.043  0.307  0.929  1.0
  O  O36  1  0.736  0.515  0.193  1.0
  O  O37  1  0.485  0.264  0.307  1.0
  O  O38  1  0.103  0.940  0.892  1.0
  O  O39  1  0.957  0.693  0.071  1.0
  O  O40  1  0.515  0.736  0.693  1.0
  O  O41  1  0.897  0.060  0.108  1.0
  O  O42  1  0.684  0.323  0.590  1.0
  O  O43  1  0.060  0.897  0.608  1.0
  O  O44  1  0.352  0.095  0.134  1.0
  O  O45  1  0.940  0.103  0.392  1.0
  O  O46  1  0.677  0.316  0.910  1.0
  O  O47  1  0.693  0.957  0.571  1.0
[/CIF]
.
The compound described by Na5Co2O5 crystallizes in the monoclinic C2/c space group. There are five inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded to one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent Co(1)O4 tetrahedra, corners with two equivalent Na(4)O4 trigonal pyramids, corners with two equivalent Na(5)O4 trigonal pyramids,  an edgeedge with one Co(1)O4 tetrahedra, edges with two equivalent Na(2)O5 trigonal bipyramids, and edges with two equivalent Na(5)O4 trigonal pyramids. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(3), one O(4), and two equivalent O(5) atoms. In the fourth Na site, Na(4) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form NaO4 trigonal pyramids that share corners with two equivalent Co(1)O4 tetrahedra, corners with two equivalent Na(2)O5 trigonal bipyramids, corners with two equivalent Na(5)O4 trigonal pyramids, and  an edgeedge with one Na(4)O4 trigonal pyramid. In the fifth Na site, Na(5) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form distorted NaO4 trigonal pyramids that share corners with two equivalent Co(1)O4 tetrahedra, corners with two equivalent Na(2)O5 trigonal bipyramids, corners with two equivalent Na(4)O4 trigonal pyramids, edges with two equivalent Na(2)O5 trigonal bipyramids, and  an edgeedge with one Na(5)O4 trigonal pyramid. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), and two equivalent O(5) atoms to form distorted CoO4 tetrahedra that share corners with two equivalent Na(2)O5 trigonal bipyramids, corners with two equivalent Na(4)O4 trigonal pyramids, corners with two equivalent Na(5)O4 trigonal pyramids,  an edgeedge with one Co(1)O4 tetrahedra, and  an edgeedge with one Na(2)O5 trigonal bipyramid. In the second Co site, Co(2) is bonded in a distorted trigonal planar geometry to one O(2), one O(3), and one O(4) atom. There are five inequivalent O sites. In the first O site, O(5) is bonded to one Na(1), one Na(2), two equivalent Na(3), and two equivalent Co(1) atoms to form distorted ONa4Co2 octahedra that share corners with four equivalent O(3)Na5Co octahedra, edges with two equivalent O(5)Na4Co2 octahedra, and edges with two equivalent O(4)Na5Co octahedra. The corner-sharing octahedral tilt angles range from 42-67°. In the second O site, O(1) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(2), two equivalent Na(5), and one Co(1) atom. In the third O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(4), one Co(1), and one Co(2) atom. In the fourth O site, O(3) is bonded to one Na(3), one Na(4), one Na(5), two equivalent Na(1), and one Co(2) atom to form distorted ONa5Co octahedra that share corners with four equivalent O(5)Na4Co2 octahedra, corners with four equivalent O(4)Na5Co octahedra, and  an edgeedge with one O(3)Na5Co octahedra. The corner-sharing octahedral tilt angles range from 42-67°. In the fifth O site, O(4) is bonded to one Na(3), one Na(4), one Na(5), two equivalent Na(2), and one Co(2) atom to form ONa5Co octahedra that share corners with four equivalent O(3)Na5Co octahedra,  an edgeedge with one O(4)Na5Co octahedra, and edges with two equivalent O(5)Na4Co2 octahedra. The corner-sharing octahedral tilt angles range from 42-55°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na5Co2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.555
_cell_length_b   8.555
_cell_length_c   11.500
_cell_angle_alpha   77.102
_cell_angle_beta   77.102
_cell_angle_gamma   57.048
_symmetry_Int_Tables_number   1
_cell_volume   683.143
_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
  Na  Na0  1  0.329  1.000  0.960  1.0
  Na  Na1  1  0.621  0.403  0.377  1.0
  Na  Na2  1  1.000  0.329  0.460  1.0
  Na  Na3  1  0.597  0.379  0.123  1.0
  Na  Na4  1  0.403  0.621  0.877  1.0
  Na  Na5  1  0.989  0.798  0.810  1.0
  Na  Na6  1  0.379  0.597  0.623  1.0
  Na  Na7  1  0.798  0.989  0.310  1.0
  Na  Na8  1  0.603  0.794  0.483  1.0
  Na  Na9  1  0.671  0.000  0.040  1.0
  Na  Na10  1  0.434  0.778  0.212  1.0
  Na  Na11  1  0.397  0.206  0.517  1.0
  Na  Na12  1  0.202  0.011  0.690  1.0
  Na  Na13  1  0.206  0.397  0.017  1.0
  Na  Na14  1  0.222  0.566  0.288  1.0
  Na  Na15  1  0.794  0.603  0.983  1.0
  Na  Na16  1  0.000  0.671  0.540  1.0
  Na  Na17  1  0.566  0.222  0.788  1.0
  Na  Na18  1  0.011  0.202  0.190  1.0
  Na  Na19  1  0.778  0.434  0.712  1.0
  Co  Co20  1  0.184  0.915  0.443  1.0
  Co  Co21  1  0.386  0.144  0.268  1.0
  Co  Co22  1  0.085  0.816  0.057  1.0
  Co  Co23  1  0.856  0.614  0.232  1.0
  Co  Co24  1  0.816  0.085  0.557  1.0
  Co  Co25  1  0.915  0.184  0.943  1.0
  Co  Co26  1  0.144  0.386  0.768  1.0
  Co  Co27  1  0.614  0.856  0.732  1.0
  O  O28  1  0.323  0.684  0.090  1.0
  O  O29  1  0.307  0.043  0.429  1.0
  O  O30  1  0.316  0.677  0.410  1.0
  O  O31  1  0.905  0.648  0.366  1.0
  O  O32  1  0.095  0.352  0.634  1.0
  O  O33  1  0.648  0.905  0.866  1.0
  O  O34  1  0.264  0.485  0.807  1.0
  O  O35  1  0.043  0.307  0.929  1.0
  O  O36  1  0.736  0.515  0.193  1.0
  O  O37  1  0.485  0.264  0.307  1.0
  O  O38  1  0.103  0.940  0.892  1.0
  O  O39  1  0.957  0.693  0.071  1.0
  O  O40  1  0.515  0.736  0.693  1.0
  O  O41  1  0.897  0.060  0.108  1.0
  O  O42  1  0.684  0.323  0.590  1.0
  O  O43  1  0.060  0.897  0.608  1.0
  O  O44  1  0.352  0.095  0.134  1.0
  O  O45  1  0.940  0.103  0.392  1.0
  O  O46  1  0.677  0.316  0.910  1.0
  O  O47  1  0.693  0.957  0.571  1.0
[/CIF]
.