Na2CuO2 crystallizes in the orthorhombic Cmc2_1 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(2) and three equivalent O(1) atoms. In the second Na site, Na(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted corner-sharing NaO4 tetrahedra. 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(2), three equivalent Na(1), and two equivalent Cu(1) atoms. In the second O site, O(2) is bonded to two equivalent Na(1), two equivalent Na(2), and two equivalent Cu(1) atoms to form a mixture of corner and edge-sharing ONa4Cu2 octahedra. The corner-sharing octahedral tilt angles are 56°.
Na2CuO2 crystallizes in the orthorhombic Cmc2_1 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(2) and three equivalent O(1) atoms. Both Na(1)-O(2) bond lengths are 2.34 Å. There is one shorter (2.55 Å) and two longer (2.57 Å) Na(1)-O(1) bond lengths. In the second Na site, Na(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted corner-sharing NaO4 tetrahedra. Both Na(2)-O(1) bond lengths are 2.33 Å. There is one shorter (2.31 Å) and one longer (2.38 Å) Na(2)-O(2) 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 2.00 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(2), three equivalent Na(1), and two equivalent Cu(1) atoms. In the second O site, O(2) is bonded to two equivalent Na(1), two equivalent Na(2), and two equivalent Cu(1) atoms to form a mixture of corner and edge-sharing ONa4Cu2 octahedra. The corner-sharing octahedral tilt angles are 56°.