NaCu2O3 crystallizes in the monoclinic C2/m space group. Na(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted NaO6 octahedra that share edges with three equivalent Na(1)O6 octahedra and edges with three equivalent Cu(3)O6 octahedra. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to four equivalent O(1) atoms. In the third Cu site, Cu(3) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted CuO6 octahedra that share edges with six equivalent Na(1)O6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), one Cu(1), one Cu(2), and one Cu(3) atom to form a mixture of distorted corner and edge-sharing ONa2Cu3 square pyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Na(1), one Cu(3), and two equivalent Cu(1) atoms.
NaCu2O3 crystallizes in the monoclinic C2/m space group. Na(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted NaO6 octahedra that share edges with three equivalent Na(1)O6 octahedra and edges with three equivalent Cu(3)O6 octahedra. Both Na(1)-O(2) bond lengths are 2.41 Å. There are two shorter (2.33 Å) and two longer (2.34 Å) Na(1)-O(1) bond lengths. There are three inequivalent Cu sites. In the first Cu site, 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 1.92 Å. Both Cu(1)-O(2) bond lengths are 1.93 Å. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to four equivalent O(1) atoms. All Cu(2)-O(1) bond lengths are 1.84 Å. In the third Cu site, Cu(3) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted CuO6 octahedra that share edges with six equivalent Na(1)O6 octahedra. Both Cu(3)-O(2) bond lengths are 1.98 Å. All Cu(3)-O(1) bond lengths are 2.26 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), one Cu(1), one Cu(2), and one Cu(3) atom to form a mixture of distorted corner and edge-sharing ONa2Cu3 square pyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Na(1), one Cu(3), and two equivalent Cu(1) atoms.