The structure described by Na2(NiO2)5 crystallizes in the triclinic P-1 space group. Na(1) is bonded in a distorted hexagonal planar geometry to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form edge-sharing NiO6 octahedra. In the second Ni site, Ni(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form edge-sharing NiO6 octahedra. In the third Ni site, Ni(3) is bonded to one O(2), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form edge-sharing NiO6 octahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted ONaNi3 trigonal pyramids that share corners with two equivalent O(2)Na2Ni3 square pyramids,  a cornercorner with one O(1)NaNi3 trigonal pyramid,  a cornercorner with one O(3)NaNi3 trigonal pyramid, corners with three equivalent O(4)NaNi3 trigonal pyramids, corners with three equivalent O(5)NaNi3 trigonal pyramids, edges with two equivalent O(2)Na2Ni3 square pyramids,  an edgeedge with one O(1)NaNi3 trigonal pyramid, and edges with two equivalent O(3)NaNi3 trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Na(1), one Ni(1), one Ni(2), and one Ni(3) atom to form distorted ONa2Ni3 square pyramids that share  a cornercorner with one O(2)Na2Ni3 square pyramid,  a cornercorner with one O(5)NaNi3 trigonal pyramid, corners with two equivalent O(1)NaNi3 trigonal pyramids, corners with two equivalent O(3)NaNi3 trigonal pyramids, corners with three equivalent O(4)NaNi3 trigonal pyramids,  an edgeedge with one O(2)Na2Ni3 square pyramid,  an edgeedge with one O(4)NaNi3 trigonal pyramid, edges with two equivalent O(1)NaNi3 trigonal pyramids, edges with two equivalent O(3)NaNi3 trigonal pyramids, and edges with two equivalent O(5)NaNi3 trigonal pyramids. In the third O site, O(3) is bonded to one Na(1), one Ni(1), one Ni(2), and one Ni(3) atom to form distorted ONaNi3 trigonal pyramids that share corners with two equivalent O(2)Na2Ni3 square pyramids,  a cornercorner with one O(1)NaNi3 trigonal pyramid,  a cornercorner with one O(3)NaNi3 trigonal pyramid, corners with two equivalent O(4)NaNi3 trigonal pyramids, corners with four equivalent O(5)NaNi3 trigonal pyramids, edges with two equivalent O(2)Na2Ni3 square pyramids,  an edgeedge with one O(4)NaNi3 trigonal pyramid, and edges with two equivalent O(1)NaNi3 trigonal pyramids. In the fourth O site, O(4) is bonded to one Na(1), one Ni(1), and two equivalent Ni(3) atoms to form distorted ONaNi3 trigonal pyramids that share corners with three equivalent O(2)Na2Ni3 square pyramids, corners with two equivalent O(3)NaNi3 trigonal pyramids, corners with two equivalent O(5)NaNi3 trigonal pyramids, corners with three equivalent O(1)NaNi3 trigonal pyramids,  an edgeedge with one O(2)Na2Ni3 square pyramid,  an edgeedge with one O(3)NaNi3 trigonal pyramid,  an edgeedge with one O(4)NaNi3 trigonal pyramid, and edges with two equivalent O(5)NaNi3 trigonal pyramids. In the fifth O site, O(5) is bonded to one Na(1), one Ni(1), and two equivalent Ni(3) atoms to form distorted ONaNi3 trigonal pyramids that share  a cornercorner with one O(2)Na2Ni3 square pyramid, corners with two equivalent O(4)NaNi3 trigonal pyramids, corners with three equivalent O(1)NaNi3 trigonal pyramids, corners with four equivalent O(3)NaNi3 trigonal pyramids, edges with two equivalent O(2)Na2Ni3 square pyramids,  an edgeedge with one O(5)NaNi3 trigonal pyramid, and edges with two equivalent O(4)NaNi3 trigonal pyramids. is represented by the CIF file [CIF]
data_Na2(NiO2)5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.892
_cell_length_b   6.407
_cell_length_c   6.967
_cell_angle_alpha   113.066
_cell_angle_beta   96.440
_cell_angle_gamma   104.496
_symmetry_Int_Tables_number   1
_cell_volume   189.046
_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
  Na  Na0  1  0.621  0.233  0.730  1.0
  Na  Na1  1  0.379  0.767  0.270  1.0
  Ni  Ni2  1  0.604  0.704  0.699  1.0
  Ni  Ni3  1  0.000  0.500  0.500  1.0
  Ni  Ni4  1  0.396  0.296  0.301  1.0
  Ni  Ni5  1  0.797  0.097  0.103  1.0
  Ni  Ni6  1  0.203  0.903  0.897  1.0
  O  O7  1  0.675  0.601  0.425  1.0
  O  O8  1  0.325  0.399  0.575  1.0
  O  O9  1  0.685  0.178  0.368  1.0
  O  O10  1  0.085  0.397  0.232  1.0
  O  O11  1  0.315  0.822  0.632  1.0
  O  O12  1  0.915  0.603  0.768  1.0
  O  O13  1  0.115  0.991  0.169  1.0
  O  O14  1  0.482  0.204  0.031  1.0
  O  O15  1  0.885  0.009  0.831  1.0
  O  O16  1  0.518  0.796  0.969  1.0
[/CIF]
.
The structure described by Na2(NiO2)5 crystallizes in the triclinic P-1 space group. Na(1) is bonded in a distorted hexagonal planar geometry to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form edge-sharing NiO6 octahedra. In the second Ni site, Ni(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form edge-sharing NiO6 octahedra. In the third Ni site, Ni(3) is bonded to one O(2), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form edge-sharing NiO6 octahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted ONaNi3 trigonal pyramids that share corners with two equivalent O(2)Na2Ni3 square pyramids,  a cornercorner with one O(1)NaNi3 trigonal pyramid,  a cornercorner with one O(3)NaNi3 trigonal pyramid, corners with three equivalent O(4)NaNi3 trigonal pyramids, corners with three equivalent O(5)NaNi3 trigonal pyramids, edges with two equivalent O(2)Na2Ni3 square pyramids,  an edgeedge with one O(1)NaNi3 trigonal pyramid, and edges with two equivalent O(3)NaNi3 trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Na(1), one Ni(1), one Ni(2), and one Ni(3) atom to form distorted ONa2Ni3 square pyramids that share  a cornercorner with one O(2)Na2Ni3 square pyramid,  a cornercorner with one O(5)NaNi3 trigonal pyramid, corners with two equivalent O(1)NaNi3 trigonal pyramids, corners with two equivalent O(3)NaNi3 trigonal pyramids, corners with three equivalent O(4)NaNi3 trigonal pyramids,  an edgeedge with one O(2)Na2Ni3 square pyramid,  an edgeedge with one O(4)NaNi3 trigonal pyramid, edges with two equivalent O(1)NaNi3 trigonal pyramids, edges with two equivalent O(3)NaNi3 trigonal pyramids, and edges with two equivalent O(5)NaNi3 trigonal pyramids. In the third O site, O(3) is bonded to one Na(1), one Ni(1), one Ni(2), and one Ni(3) atom to form distorted ONaNi3 trigonal pyramids that share corners with two equivalent O(2)Na2Ni3 square pyramids,  a cornercorner with one O(1)NaNi3 trigonal pyramid,  a cornercorner with one O(3)NaNi3 trigonal pyramid, corners with two equivalent O(4)NaNi3 trigonal pyramids, corners with four equivalent O(5)NaNi3 trigonal pyramids, edges with two equivalent O(2)Na2Ni3 square pyramids,  an edgeedge with one O(4)NaNi3 trigonal pyramid, and edges with two equivalent O(1)NaNi3 trigonal pyramids. In the fourth O site, O(4) is bonded to one Na(1), one Ni(1), and two equivalent Ni(3) atoms to form distorted ONaNi3 trigonal pyramids that share corners with three equivalent O(2)Na2Ni3 square pyramids, corners with two equivalent O(3)NaNi3 trigonal pyramids, corners with two equivalent O(5)NaNi3 trigonal pyramids, corners with three equivalent O(1)NaNi3 trigonal pyramids,  an edgeedge with one O(2)Na2Ni3 square pyramid,  an edgeedge with one O(3)NaNi3 trigonal pyramid,  an edgeedge with one O(4)NaNi3 trigonal pyramid, and edges with two equivalent O(5)NaNi3 trigonal pyramids. In the fifth O site, O(5) is bonded to one Na(1), one Ni(1), and two equivalent Ni(3) atoms to form distorted ONaNi3 trigonal pyramids that share  a cornercorner with one O(2)Na2Ni3 square pyramid, corners with two equivalent O(4)NaNi3 trigonal pyramids, corners with three equivalent O(1)NaNi3 trigonal pyramids, corners with four equivalent O(3)NaNi3 trigonal pyramids, edges with two equivalent O(2)Na2Ni3 square pyramids,  an edgeedge with one O(5)NaNi3 trigonal pyramid, and edges with two equivalent O(4)NaNi3 trigonal pyramids. is represented by the CIF file [CIF]
data_Na2(NiO2)5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.892
_cell_length_b   6.407
_cell_length_c   6.967
_cell_angle_alpha   113.066
_cell_angle_beta   96.440
_cell_angle_gamma   104.496
_symmetry_Int_Tables_number   1
_cell_volume   189.046
_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
  Na  Na0  1  0.621  0.233  0.730  1.0
  Na  Na1  1  0.379  0.767  0.270  1.0
  Ni  Ni2  1  0.604  0.704  0.699  1.0
  Ni  Ni3  1  0.000  0.500  0.500  1.0
  Ni  Ni4  1  0.396  0.296  0.301  1.0
  Ni  Ni5  1  0.797  0.097  0.103  1.0
  Ni  Ni6  1  0.203  0.903  0.897  1.0
  O  O7  1  0.675  0.601  0.425  1.0
  O  O8  1  0.325  0.399  0.575  1.0
  O  O9  1  0.685  0.178  0.368  1.0
  O  O10  1  0.085  0.397  0.232  1.0
  O  O11  1  0.315  0.822  0.632  1.0
  O  O12  1  0.915  0.603  0.768  1.0
  O  O13  1  0.115  0.991  0.169  1.0
  O  O14  1  0.482  0.204  0.031  1.0
  O  O15  1  0.885  0.009  0.831  1.0
  O  O16  1  0.518  0.796  0.969  1.0
[/CIF]
.