Cu2AsO5 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(3), one O(4), one O(5), and two equivalent O(1) atoms to form CuO5 square pyramids that share corners with four equivalent Cu(2)O6 octahedra, corners with four equivalent As(1)O4 tetrahedra, and  an edgeedge with one Cu(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 48-57°. In the second Cu site, Cu(2) is bonded to one O(4), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form CuO6 octahedra that share corners with four equivalent Cu(1)O5 square pyramids, corners with four equivalent As(1)O4 tetrahedra, and edges with two equivalent Cu(2)O6 octahedra. As(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form AsO4 tetrahedra that share corners with four equivalent Cu(2)O6 octahedra and corners with four equivalent Cu(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 55-72°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Cu(1) and one As(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Cu(2) and one As(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Cu(1) and two equivalent Cu(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one As(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one As(1) atom.
Cu2AsO5 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(3), one O(4), one O(5), and two equivalent O(1) atoms to form CuO5 square pyramids that share corners with four equivalent Cu(2)O6 octahedra, corners with four equivalent As(1)O4 tetrahedra, and  an edgeedge with one Cu(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 48-57°. The Cu(1)-O(3) bond length is 1.83 Å. The Cu(1)-O(4) bond length is 1.94 Å. The Cu(1)-O(5) bond length is 2.12 Å. There is one shorter (1.94 Å) and one longer (1.95 Å) Cu(1)-O(1) bond length. In the second Cu site, Cu(2) is bonded to one O(4), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form CuO6 octahedra that share corners with four equivalent Cu(1)O5 square pyramids, corners with four equivalent As(1)O4 tetrahedra, and edges with two equivalent Cu(2)O6 octahedra. The Cu(2)-O(4) bond length is 2.35 Å. The Cu(2)-O(5) bond length is 2.31 Å. There is one shorter (1.92 Å) and one longer (1.95 Å) Cu(2)-O(2) bond length. There is one shorter (1.86 Å) and one longer (1.88 Å) Cu(2)-O(3) bond length. As(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form AsO4 tetrahedra that share corners with four equivalent Cu(2)O6 octahedra and corners with four equivalent Cu(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 55-72°. The As(1)-O(1) bond length is 1.73 Å. The As(1)-O(2) bond length is 1.73 Å. The As(1)-O(4) bond length is 1.70 Å. The As(1)-O(5) bond length is 1.67 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Cu(1) and one As(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Cu(2) and one As(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Cu(1) and two equivalent Cu(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one As(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one As(1) atom.