Na3CuO3 crystallizes in the tetragonal P4_2/mnm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(2) atoms. Cu(1) is bonded in a rectangular see-saw-like 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 to two equivalent Na(1), two equivalent Na(2), and two equivalent Cu(1) atoms to form a mixture of distorted corner and edge-sharing ONa4Cu2 octahedra. The corner-sharing octahedral tilt angles are 33°. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(2), four equivalent Na(1), and one Cu(1) atom.
Na3CuO3 crystallizes in the tetragonal P4_2/mnm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(2) atoms. The Na(1)-O(1) bond length is 2.54 Å. There are a spread of Na(1)-O(2) bond distances ranging from 2.21-2.86 Å. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Na(2)-O(1) bond lengths are 2.31 Å. Both Na(2)-O(2) bond lengths are 2.26 Å. Cu(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Cu(1)-O(1) bond lengths are 1.88 Å. Both Cu(1)-O(2) bond lengths are 1.82 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), two equivalent Na(2), and two equivalent Cu(1) atoms to form a mixture of distorted corner and edge-sharing ONa4Cu2 octahedra. The corner-sharing octahedral tilt angles are 33°. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(2), four equivalent Na(1), and one Cu(1) atom.