Cu8O crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a single-bond geometry to two equivalent Cu(2), four equivalent Cu(3), and one O(1) atom. In the second Cu site, Cu(2) is bonded to two equivalent Cu(1), two equivalent Cu(2), four equivalent Cu(3), and four equivalent Cu(4) atoms to form CuCu12 cuboctahedra that share corners with four equivalent Cu(2)Cu12 cuboctahedra, corners with two equivalent O(1)Cu4 tetrahedra, edges with four equivalent Cu(2)Cu12 cuboctahedra, edges with eight equivalent Cu(3)Cu12 cuboctahedra, edges with two equivalent O(1)Cu4 tetrahedra, faces with four equivalent Cu(2)Cu12 cuboctahedra, and faces with four equivalent Cu(3)Cu12 cuboctahedra. In the third Cu site, Cu(3) is bonded to two equivalent Cu(3), two equivalent Cu(4), four equivalent Cu(1), and four equivalent Cu(2) atoms to form CuCu12 cuboctahedra that share corners with twelve equivalent Cu(3)Cu12 cuboctahedra, edges with four equivalent Cu(3)Cu12 cuboctahedra, edges with eight equivalent Cu(2)Cu12 cuboctahedra, edges with three equivalent O(1)Cu4 tetrahedra, faces with two equivalent Cu(3)Cu12 cuboctahedra, and faces with four equivalent Cu(2)Cu12 cuboctahedra. In the fourth Cu site, Cu(4) is bonded in a single-bond geometry to two equivalent Cu(3), four equivalent Cu(2), and one O(1) atom. O(1) is bonded to two equivalent Cu(1) and two equivalent Cu(4) atoms to form OCu4 tetrahedra that share corners with four equivalent Cu(2)Cu12 cuboctahedra, edges with four equivalent Cu(2)Cu12 cuboctahedra, and edges with six equivalent Cu(3)Cu12 cuboctahedra.
Cu8O crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a single-bond geometry to two equivalent Cu(2), four equivalent Cu(3), and one O(1) atom. Both Cu(1)-Cu(2) bond lengths are 2.70 Å. There are two shorter (2.66 Å) and two longer (2.74 Å) Cu(1)-Cu(3) bond lengths. The Cu(1)-O(1) bond length is 1.85 Å. In the second Cu site, Cu(2) is bonded to two equivalent Cu(1), two equivalent Cu(2), four equivalent Cu(3), and four equivalent Cu(4) atoms to form CuCu12 cuboctahedra that share corners with four equivalent Cu(2)Cu12 cuboctahedra, corners with two equivalent O(1)Cu4 tetrahedra, edges with four equivalent Cu(2)Cu12 cuboctahedra, edges with eight equivalent Cu(3)Cu12 cuboctahedra, edges with two equivalent O(1)Cu4 tetrahedra, faces with four equivalent Cu(2)Cu12 cuboctahedra, and faces with four equivalent Cu(3)Cu12 cuboctahedra. There is one shorter (2.72 Å) and one longer (2.79 Å) Cu(2)-Cu(2) bond length. There are two shorter (2.58 Å) and two longer (2.65 Å) Cu(2)-Cu(3) bond lengths. There are two shorter (2.52 Å) and two longer (2.61 Å) Cu(2)-Cu(4) bond lengths. In the third Cu site, Cu(3) is bonded to two equivalent Cu(3), two equivalent Cu(4), four equivalent Cu(1), and four equivalent Cu(2) atoms to form CuCu12 cuboctahedra that share corners with twelve equivalent Cu(3)Cu12 cuboctahedra, edges with four equivalent Cu(3)Cu12 cuboctahedra, edges with eight equivalent Cu(2)Cu12 cuboctahedra, edges with three equivalent O(1)Cu4 tetrahedra, faces with two equivalent Cu(3)Cu12 cuboctahedra, and faces with four equivalent Cu(2)Cu12 cuboctahedra. There is one shorter (2.52 Å) and one longer (2.84 Å) Cu(3)-Cu(3) bond length. Both Cu(3)-Cu(4) bond lengths are 2.76 Å. In the fourth Cu site, Cu(4) is bonded in a single-bond geometry to two equivalent Cu(3), four equivalent Cu(2), and one O(1) atom. The Cu(4)-O(1) bond length is 1.90 Å. O(1) is bonded to two equivalent Cu(1) and two equivalent Cu(4) atoms to form OCu4 tetrahedra that share corners with four equivalent Cu(2)Cu12 cuboctahedra, edges with four equivalent Cu(2)Cu12 cuboctahedra, and edges with six equivalent Cu(3)Cu12 cuboctahedra.