The crystal structure described by Na2MnO2 crystallizes in the monoclinic C2/c space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted NaO4 trigonal pyramids that share  a cornercorner with one Mn(1)O4 tetrahedra, corners with three equivalent Mn(2)O4 tetrahedra,  an edgeedge with one Mn(1)O4 tetrahedra,  an edgeedge with one Mn(2)O4 tetrahedra, and  an edgeedge with one Na(3)O4 trigonal pyramid. In the fourth Na site, Na(4) is bonded in a 5-coordinate geometry to one O(1), one O(2), and three equivalent O(3) atoms. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form distorted MnO4 tetrahedra that share corners with four equivalent Mn(2)O4 tetrahedra, corners with two equivalent Na(3)O4 trigonal pyramids, and edges with two equivalent Na(3)O4 trigonal pyramids. In the second Mn site, Mn(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form MnO4 tetrahedra that share corners with two equivalent Mn(1)O4 tetrahedra, corners with two equivalent Mn(2)O4 tetrahedra, corners with three equivalent Na(3)O4 trigonal pyramids, and  an edgeedge with one Na(3)O4 trigonal pyramid. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(4), two equivalent Na(3), one Mn(1), and one Mn(2) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), and two equivalent Mn(2) atoms. In the third O site, O(3) is bonded in a 7-coordinate geometry to one Na(2), one Na(3), three equivalent Na(4), one Mn(1), and one Mn(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2MnO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.084
_cell_length_b   8.577
_cell_length_c   8.577
_cell_angle_alpha   86.891
_cell_angle_beta   69.585
_cell_angle_gamma   69.585
_symmetry_Int_Tables_number   1
_cell_volume   392.009
_cell_formula_units_Z   6
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  0.250  0.938  0.062  1.0
  Na  Na1  1  0.750  0.062  0.938  1.0
  Na  Na2  1  0.750  0.801  0.199  1.0
  Na  Na3  1  0.250  0.199  0.801  1.0
  Na  Na4  1  0.736  0.402  0.996  1.0
  Na  Na5  1  0.764  0.004  0.598  1.0
  Na  Na6  1  0.264  0.598  0.004  1.0
  Na  Na7  1  0.236  0.996  0.402  1.0
  Na  Na8  1  0.228  0.324  0.469  1.0
  Na  Na9  1  0.772  0.676  0.531  1.0
  Na  Na10  1  0.728  0.469  0.324  1.0
  Na  Na11  1  0.272  0.531  0.676  1.0
  Mn  Mn12  1  0.250  0.679  0.321  1.0
  Mn  Mn13  1  0.257  0.289  0.132  1.0
  Mn  Mn14  1  0.243  0.868  0.711  1.0
  Mn  Mn15  1  0.750  0.321  0.679  1.0
  Mn  Mn16  1  0.743  0.711  0.868  1.0
  Mn  Mn17  1  0.757  0.132  0.289  1.0
  O  O18  1  0.468  0.327  0.899  1.0
  O  O19  1  0.032  0.101  0.673  1.0
  O  O20  1  0.532  0.673  0.101  1.0
  O  O21  1  0.968  0.899  0.327  1.0
  O  O22  1  0.513  0.894  0.780  1.0
  O  O23  1  0.987  0.220  0.106  1.0
  O  O24  1  0.013  0.780  0.894  1.0
  O  O25  1  0.487  0.106  0.220  1.0
  O  O26  1  0.596  0.280  0.516  1.0
  O  O27  1  0.904  0.484  0.720  1.0
  O  O28  1  0.096  0.516  0.280  1.0
  O  O29  1  0.404  0.720  0.484  1.0
[/CIF]
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The crystal structure described by Na2MnO2 crystallizes in the monoclinic C2/c space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted NaO4 trigonal pyramids that share  a cornercorner with one Mn(1)O4 tetrahedra, corners with three equivalent Mn(2)O4 tetrahedra,  an edgeedge with one Mn(1)O4 tetrahedra,  an edgeedge with one Mn(2)O4 tetrahedra, and  an edgeedge with one Na(3)O4 trigonal pyramid. In the fourth Na site, Na(4) is bonded in a 5-coordinate geometry to one O(1), one O(2), and three equivalent O(3) atoms. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form distorted MnO4 tetrahedra that share corners with four equivalent Mn(2)O4 tetrahedra, corners with two equivalent Na(3)O4 trigonal pyramids, and edges with two equivalent Na(3)O4 trigonal pyramids. In the second Mn site, Mn(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form MnO4 tetrahedra that share corners with two equivalent Mn(1)O4 tetrahedra, corners with two equivalent Mn(2)O4 tetrahedra, corners with three equivalent Na(3)O4 trigonal pyramids, and  an edgeedge with one Na(3)O4 trigonal pyramid. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(4), two equivalent Na(3), one Mn(1), and one Mn(2) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), and two equivalent Mn(2) atoms. In the third O site, O(3) is bonded in a 7-coordinate geometry to one Na(2), one Na(3), three equivalent Na(4), one Mn(1), and one Mn(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2MnO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.084
_cell_length_b   8.577
_cell_length_c   8.577
_cell_angle_alpha   86.891
_cell_angle_beta   69.585
_cell_angle_gamma   69.585
_symmetry_Int_Tables_number   1
_cell_volume   392.009
_cell_formula_units_Z   6
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  0.250  0.938  0.062  1.0
  Na  Na1  1  0.750  0.062  0.938  1.0
  Na  Na2  1  0.750  0.801  0.199  1.0
  Na  Na3  1  0.250  0.199  0.801  1.0
  Na  Na4  1  0.736  0.402  0.996  1.0
  Na  Na5  1  0.764  0.004  0.598  1.0
  Na  Na6  1  0.264  0.598  0.004  1.0
  Na  Na7  1  0.236  0.996  0.402  1.0
  Na  Na8  1  0.228  0.324  0.469  1.0
  Na  Na9  1  0.772  0.676  0.531  1.0
  Na  Na10  1  0.728  0.469  0.324  1.0
  Na  Na11  1  0.272  0.531  0.676  1.0
  Mn  Mn12  1  0.250  0.679  0.321  1.0
  Mn  Mn13  1  0.257  0.289  0.132  1.0
  Mn  Mn14  1  0.243  0.868  0.711  1.0
  Mn  Mn15  1  0.750  0.321  0.679  1.0
  Mn  Mn16  1  0.743  0.711  0.868  1.0
  Mn  Mn17  1  0.757  0.132  0.289  1.0
  O  O18  1  0.468  0.327  0.899  1.0
  O  O19  1  0.032  0.101  0.673  1.0
  O  O20  1  0.532  0.673  0.101  1.0
  O  O21  1  0.968  0.899  0.327  1.0
  O  O22  1  0.513  0.894  0.780  1.0
  O  O23  1  0.987  0.220  0.106  1.0
  O  O24  1  0.013  0.780  0.894  1.0
  O  O25  1  0.487  0.106  0.220  1.0
  O  O26  1  0.596  0.280  0.516  1.0
  O  O27  1  0.904  0.484  0.720  1.0
  O  O28  1  0.096  0.516  0.280  1.0
  O  O29  1  0.404  0.720  0.484  1.0
[/CIF]
.