Na3Cu2O4 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(1), one O(4), and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded to one O(1), one O(2), one O(3), and two equivalent O(4) atoms to form distorted edge-sharing NaO5 trigonal bipyramids. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Na(3), one Cu(1), and one Cu(2) atom to form distorted ONa3Cu2 trigonal bipyramids that share corners with four equivalent O(4)Na4Cu2 octahedra, corners with three equivalent O(2)Na4Cu2 pentagonal pyramids,  a cornercorner with one O(3)Na3Cu2 trigonal bipyramid,  an edgeedge with one O(4)Na4Cu2 octahedra, edges with two equivalent O(3)Na3Cu2 trigonal bipyramids, and  a faceface with one O(2)Na4Cu2 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 5-53°. In the second O site, O(2) is bonded to one Na(2), one Na(3), two equivalent Na(1), one Cu(1), and one Cu(2) atom to form distorted ONa4Cu2 pentagonal pyramids that share corners with two equivalent O(4)Na4Cu2 octahedra, corners with three equivalent O(1)Na3Cu2 trigonal bipyramids, corners with three equivalent O(3)Na3Cu2 trigonal bipyramids,  an edgeedge with one O(4)Na4Cu2 octahedra,  an edgeedge with one O(2)Na4Cu2 pentagonal pyramid,  an edgeedge with one O(3)Na3Cu2 trigonal bipyramid,  a faceface with one O(4)Na4Cu2 octahedra, and  a faceface with one O(1)Na3Cu2 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 58-60°. In the third O site, O(3) is bonded to one Na(3), two equivalent Na(2), one Cu(1), and one Cu(2) atom to form distorted ONa3Cu2 trigonal bipyramids that share corners with two equivalent O(4)Na4Cu2 octahedra, corners with three equivalent O(2)Na4Cu2 pentagonal pyramids,  a cornercorner with one O(1)Na3Cu2 trigonal bipyramid, corners with two equivalent O(3)Na3Cu2 trigonal bipyramids, edges with two equivalent O(4)Na4Cu2 octahedra,  an edgeedge with one O(2)Na4Cu2 pentagonal pyramid, and edges with two equivalent O(1)Na3Cu2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 1-56°. In the fourth O site, O(4) is bonded to one Na(1), one Na(2), two equivalent Na(3), one Cu(1), and one Cu(2) atom to form distorted ONa4Cu2 octahedra that share corners with two equivalent O(2)Na4Cu2 pentagonal pyramids, corners with two equivalent O(3)Na3Cu2 trigonal bipyramids, corners with four equivalent O(1)Na3Cu2 trigonal bipyramids,  an edgeedge with one O(4)Na4Cu2 octahedra,  an edgeedge with one O(2)Na4Cu2 pentagonal pyramid,  an edgeedge with one O(1)Na3Cu2 trigonal bipyramid, edges with two equivalent O(3)Na3Cu2 trigonal bipyramids, and  a faceface with one O(2)Na4Cu2 pentagonal pyramid.
Na3Cu2O4 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(1), one O(4), and two equivalent O(2) atoms. The Na(1)-O(1) bond length is 2.34 Å. The Na(1)-O(4) bond length is 2.41 Å. There is one shorter (2.28 Å) and one longer (2.55 Å) Na(1)-O(2) bond length. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. The Na(2)-O(1) bond length is 2.28 Å. The Na(2)-O(2) bond length is 2.59 Å. The Na(2)-O(4) bond length is 2.40 Å. There is one shorter (2.25 Å) and one longer (2.28 Å) Na(2)-O(3) bond length. In the third Na site, Na(3) is bonded to one O(1), one O(2), one O(3), and two equivalent O(4) atoms to form distorted edge-sharing NaO5 trigonal bipyramids. The Na(3)-O(1) bond length is 2.29 Å. The Na(3)-O(2) bond length is 2.39 Å. The Na(3)-O(3) bond length is 2.32 Å. There is one shorter (2.35 Å) and one longer (2.40 Å) Na(3)-O(4) bond length. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Cu(1)-O(1) bond length is 1.83 Å. The Cu(1)-O(2) bond length is 1.84 Å. The Cu(1)-O(3) bond length is 1.86 Å. The Cu(1)-O(4) bond length is 1.87 Å. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Cu(2)-O(1) bond length is 1.90 Å. The Cu(2)-O(2) bond length is 1.91 Å. The Cu(2)-O(3) bond length is 1.91 Å. The Cu(2)-O(4) bond length is 1.91 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Na(3), one Cu(1), and one Cu(2) atom to form distorted ONa3Cu2 trigonal bipyramids that share corners with four equivalent O(4)Na4Cu2 octahedra, corners with three equivalent O(2)Na4Cu2 pentagonal pyramids,  a cornercorner with one O(3)Na3Cu2 trigonal bipyramid,  an edgeedge with one O(4)Na4Cu2 octahedra, edges with two equivalent O(3)Na3Cu2 trigonal bipyramids, and  a faceface with one O(2)Na4Cu2 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 5-53°. In the second O site, O(2) is bonded to one Na(2), one Na(3), two equivalent Na(1), one Cu(1), and one Cu(2) atom to form distorted ONa4Cu2 pentagonal pyramids that share corners with two equivalent O(4)Na4Cu2 octahedra, corners with three equivalent O(1)Na3Cu2 trigonal bipyramids, corners with three equivalent O(3)Na3Cu2 trigonal bipyramids,  an edgeedge with one O(4)Na4Cu2 octahedra,  an edgeedge with one O(2)Na4Cu2 pentagonal pyramid,  an edgeedge with one O(3)Na3Cu2 trigonal bipyramid,  a faceface with one O(4)Na4Cu2 octahedra, and  a faceface with one O(1)Na3Cu2 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 58-60°. In the third O site, O(3) is bonded to one Na(3), two equivalent Na(2), one Cu(1), and one Cu(2) atom to form distorted ONa3Cu2 trigonal bipyramids that share corners with two equivalent O(4)Na4Cu2 octahedra, corners with three equivalent O(2)Na4Cu2 pentagonal pyramids,  a cornercorner with one O(1)Na3Cu2 trigonal bipyramid, corners with two equivalent O(3)Na3Cu2 trigonal bipyramids, edges with two equivalent O(4)Na4Cu2 octahedra,  an edgeedge with one O(2)Na4Cu2 pentagonal pyramid, and edges with two equivalent O(1)Na3Cu2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 1-56°. In the fourth O site, O(4) is bonded to one Na(1), one Na(2), two equivalent Na(3), one Cu(1), and one Cu(2) atom to form distorted ONa4Cu2 octahedra that share corners with two equivalent O(2)Na4Cu2 pentagonal pyramids, corners with two equivalent O(3)Na3Cu2 trigonal bipyramids, corners with four equivalent O(1)Na3Cu2 trigonal bipyramids,  an edgeedge with one O(4)Na4Cu2 octahedra,  an edgeedge with one O(2)Na4Cu2 pentagonal pyramid,  an edgeedge with one O(1)Na3Cu2 trigonal bipyramid, edges with two equivalent O(3)Na3Cu2 trigonal bipyramids, and  a faceface with one O(2)Na4Cu2 pentagonal pyramid.