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 NaO6 octahedra that share corners with four equivalent Cu(1)O6 octahedra, edges with three equivalent Na(1)O6 octahedra, edges with three equivalent Cu(3)O6 octahedra, and edges with four equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-20°. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CuO6 octahedra that share corners with two equivalent Cu(3)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Cu(3)O6 octahedra, edges with three equivalent Cu(1)O6 octahedra, and edges with four equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-20°. In the second Cu site, Cu(2) is bonded in a distorted 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 corners with four equivalent Cu(1)O6 octahedra, edges with four equivalent Cu(1)O6 octahedra, and edges with six equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 15°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), one Cu(2), one Cu(3), and two equivalent Cu(1) atoms to form a mixture of edge and corner-sharing ONa2Cu4 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. 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 NaO6 octahedra that share corners with four equivalent Cu(1)O6 octahedra, edges with three equivalent Na(1)O6 octahedra, edges with three equivalent Cu(3)O6 octahedra, and edges with four equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-20°. Both Na(1)-O(2) bond lengths are 2.30 Å. There are two shorter (2.38 Å) and two longer (2.40 Å) Na(1)-O(1) bond lengths. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CuO6 octahedra that share corners with two equivalent Cu(3)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Cu(3)O6 octahedra, edges with three equivalent Cu(1)O6 octahedra, and edges with four equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-20°. Both Cu(1)-O(2) bond lengths are 2.03 Å. There are two shorter (2.08 Å) and two longer (2.12 Å) Cu(1)-O(1) bond lengths. In the second Cu site, Cu(2) is bonded in a distorted square co-planar geometry to four equivalent O(1) atoms. All Cu(2)-O(1) bond lengths are 1.90 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 corners with four equivalent Cu(1)O6 octahedra, edges with four equivalent Cu(1)O6 octahedra, and edges with six equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 15°. Both Cu(3)-O(2) bond lengths are 1.89 Å. All Cu(3)-O(1) bond lengths are 2.24 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), one Cu(2), one Cu(3), and two equivalent Cu(1) atoms to form a mixture of edge and corner-sharing ONa2Cu4 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. 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.