Na2CuO2 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to two equivalent O(1) and three equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to one O(2) and three equivalent O(1) atoms. Cu(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to two equivalent Na(1), three equivalent Na(2), and two equivalent Cu(1) atoms. In the second O site, O(2) is bonded to one Na(2), three equivalent Na(1), and two equivalent Cu(1) atoms to form edge-sharing ONa4Cu2 octahedra.
Na2CuO2 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to two equivalent O(1) and three equivalent O(2) atoms. Both Na(1)-O(1) bond lengths are 2.56 Å. There is one shorter (2.33 Å) and two longer (2.38 Å) Na(1)-O(2) bond lengths. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to one O(2) and three equivalent O(1) atoms. The Na(2)-O(2) bond length is 2.30 Å. There are two shorter (2.39 Å) and one longer (2.41 Å) Na(2)-O(1) bond length. Cu(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Cu(1)-O(1) bond lengths are 2.02 Å. Both Cu(1)-O(2) bond lengths are 1.97 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to two equivalent Na(1), three equivalent Na(2), and two equivalent Cu(1) atoms. In the second O site, O(2) is bonded to one Na(2), three equivalent Na(1), and two equivalent Cu(1) atoms to form edge-sharing ONa4Cu2 octahedra.