Cu2O3 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted CuO5 trigonal bipyramids that share corners with four equivalent Cu(2)O6 octahedra,  a cornercorner with one O(1)Cu3O tetrahedra, edges with three equivalent Cu(2)O6 octahedra, and edges with two equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 57-72°. In the second Cu site, Cu(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted CuO6 octahedra that share corners with six equivalent Cu(2)O6 octahedra, corners with two equivalent O(1)Cu3O tetrahedra, corners with four equivalent Cu(1)O5 trigonal bipyramids, and edges with three equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 30-62°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Cu(1), two equivalent Cu(2), and one O(1) atom to form distorted OCu3O tetrahedra that share corners with two equivalent Cu(2)O6 octahedra, corners with two equivalent O(1)Cu3O tetrahedra,  a cornercorner with one Cu(1)O5 trigonal bipyramid, corners with four equivalent O(2)Cu4 trigonal pyramids, corners with six equivalent O(3)Cu4 trigonal pyramids, and  an edgeedge with one O(2)Cu4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 70-75°. In the second O site, O(2) is bonded to two equivalent Cu(1) and two equivalent Cu(2) atoms to form distorted OCu4 trigonal pyramids that share corners with four equivalent O(1)Cu3O tetrahedra, corners with two equivalent O(2)Cu4 trigonal pyramids, corners with four equivalent O(3)Cu4 trigonal pyramids,  an edgeedge with one O(1)Cu3O tetrahedra,  an edgeedge with one O(2)Cu4 trigonal pyramid, and edges with two equivalent O(3)Cu4 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Cu(1) and two equivalent Cu(2) atoms to form OCu4 trigonal pyramids that share corners with six equivalent O(1)Cu3O tetrahedra, corners with two equivalent O(3)Cu4 trigonal pyramids, corners with four equivalent O(2)Cu4 trigonal pyramids,  an edgeedge with one O(3)Cu4 trigonal pyramid, and edges with two equivalent O(2)Cu4 trigonal pyramids.
Cu2O3 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted CuO5 trigonal bipyramids that share corners with four equivalent Cu(2)O6 octahedra,  a cornercorner with one O(1)Cu3O tetrahedra, edges with three equivalent Cu(2)O6 octahedra, and edges with two equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 57-72°. The Cu(1)-O(1) bond length is 1.93 Å. There is one shorter (2.05 Å) and one longer (2.11 Å) Cu(1)-O(2) bond length. There is one shorter (1.94 Å) and one longer (1.96 Å) Cu(1)-O(3) bond length. In the second Cu site, Cu(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted CuO6 octahedra that share corners with six equivalent Cu(2)O6 octahedra, corners with two equivalent O(1)Cu3O tetrahedra, corners with four equivalent Cu(1)O5 trigonal bipyramids, and edges with three equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 30-62°. There is one shorter (2.46 Å) and one longer (2.51 Å) Cu(2)-O(1) bond length. There is one shorter (1.87 Å) and one longer (1.88 Å) Cu(2)-O(2) bond length. There is one shorter (2.02 Å) and one longer (2.03 Å) Cu(2)-O(3) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Cu(1), two equivalent Cu(2), and one O(1) atom to form distorted OCu3O tetrahedra that share corners with two equivalent Cu(2)O6 octahedra, corners with two equivalent O(1)Cu3O tetrahedra,  a cornercorner with one Cu(1)O5 trigonal bipyramid, corners with four equivalent O(2)Cu4 trigonal pyramids, corners with six equivalent O(3)Cu4 trigonal pyramids, and  an edgeedge with one O(2)Cu4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 70-75°. The O(1)-O(1) bond length is 1.40 Å. In the second O site, O(2) is bonded to two equivalent Cu(1) and two equivalent Cu(2) atoms to form distorted OCu4 trigonal pyramids that share corners with four equivalent O(1)Cu3O tetrahedra, corners with two equivalent O(2)Cu4 trigonal pyramids, corners with four equivalent O(3)Cu4 trigonal pyramids,  an edgeedge with one O(1)Cu3O tetrahedra,  an edgeedge with one O(2)Cu4 trigonal pyramid, and edges with two equivalent O(3)Cu4 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Cu(1) and two equivalent Cu(2) atoms to form OCu4 trigonal pyramids that share corners with six equivalent O(1)Cu3O tetrahedra, corners with two equivalent O(3)Cu4 trigonal pyramids, corners with four equivalent O(2)Cu4 trigonal pyramids,  an edgeedge with one O(3)Cu4 trigonal pyramid, and edges with two equivalent O(2)Cu4 trigonal pyramids.