Cr3CuO8 crystallizes in the monoclinic C2/m space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form CrO4 tetrahedra that share corners with three equivalent Cr(2)O6 octahedra and corners with three equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-55°. In the second Cr site, Cr(2) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form CrO6 octahedra that share corners with six equivalent Cr(1)O4 tetrahedra and edges with two equivalent Cu(1)O6 octahedra. Cu(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CuO6 octahedra that share corners with six equivalent Cr(1)O4 tetrahedra and edges with two equivalent Cr(2)O6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one Cu(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Cr(1) and one Cu(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Cr(1) and one Cr(2) atom.
Cr3CuO8 crystallizes in the monoclinic C2/m space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form CrO4 tetrahedra that share corners with three equivalent Cr(2)O6 octahedra and corners with three equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-55°. The Cr(1)-O(2) bond length is 1.64 Å. The Cr(1)-O(3) bond length is 1.66 Å. Both Cr(1)-O(1) bond lengths are 1.72 Å. In the second Cr site, Cr(2) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form CrO6 octahedra that share corners with six equivalent Cr(1)O4 tetrahedra and edges with two equivalent Cu(1)O6 octahedra. Both Cr(2)-O(3) bond lengths are 1.98 Å. All Cr(2)-O(1) bond lengths are 2.02 Å. Cu(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CuO6 octahedra that share corners with six equivalent Cr(1)O4 tetrahedra and edges with two equivalent Cr(2)O6 octahedra. Both Cu(1)-O(2) bond lengths are 1.92 Å. All Cu(1)-O(1) bond lengths are 2.31 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one Cu(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Cr(1) and one Cu(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Cr(1) and one Cr(2) atom.