Cu2P2O7 crystallizes in the monoclinic C2 space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(2) atoms. In the second Cu site, Cu(2) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(3) atoms. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing PO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one P(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Cu(1) and one P(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Cu(2) and one P(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to two equivalent P(1) atoms.
Cu2P2O7 crystallizes in the monoclinic C2 space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Cu(1)-O(1) bond lengths are 1.98 Å. Both Cu(1)-O(2) bond lengths are 1.92 Å. In the second Cu site, Cu(2) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(3) atoms. Both Cu(2)-O(1) bond lengths are 1.98 Å. Both Cu(2)-O(3) bond lengths are 1.92 Å. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing PO4 tetrahedra. The P(1)-O(1) bond length is 1.54 Å. The P(1)-O(2) bond length is 1.51 Å. The P(1)-O(3) bond length is 1.51 Å. The P(1)-O(4) bond length is 1.57 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one P(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Cu(1) and one P(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Cu(2) and one P(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to two equivalent P(1) atoms.