Li3CuP2O7 crystallizes in the triclinic P-1 space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(3), one O(6), and two equivalent O(7) atoms to form LiO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Li(1)O4 tetrahedra. In the second Li site, Li(2) is bonded to one O(1), one O(4), and two equivalent O(2) atoms to form LiO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. In the third Li site, Li(3) is bonded in a 3-coordinate geometry to one O(1), one O(4), and one O(7) atom. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to two equivalent O(3) and two equivalent O(6) atoms. In the second Cu site, Cu(2) is bonded in a distorted square co-planar geometry to two equivalent O(1) and two equivalent O(4) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Li(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with three equivalent Li(2)O4 tetrahedra. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with three equivalent Li(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Li(2), one Li(3), one Cu(2), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Li(2) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Li(1), one Cu(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Li(2), one Li(3), one Cu(2), and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Li(1), one Cu(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to one Li(3), two equivalent Li(1), and one P(2) atom.
Li3CuP2O7 crystallizes in the triclinic P-1 space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(3), one O(6), and two equivalent O(7) atoms to form LiO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Li(1)O4 tetrahedra. The Li(1)-O(3) bond length is 1.90 Å. The Li(1)-O(6) bond length is 1.94 Å. There is one shorter (1.99 Å) and one longer (2.06 Å) Li(1)-O(7) bond length. In the second Li site, Li(2) is bonded to one O(1), one O(4), and two equivalent O(2) atoms to form LiO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. The Li(2)-O(1) bond length is 1.98 Å. The Li(2)-O(4) bond length is 1.95 Å. There is one shorter (1.89 Å) and one longer (1.95 Å) Li(2)-O(2) bond length. In the third Li site, Li(3) is bonded in a 3-coordinate geometry to one O(1), one O(4), and one O(7) atom. The Li(3)-O(1) bond length is 1.96 Å. The Li(3)-O(4) bond length is 1.98 Å. The Li(3)-O(7) bond length is 1.92 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to two equivalent O(3) and two equivalent O(6) atoms. Both Cu(1)-O(3) bond lengths are 2.25 Å. Both Cu(1)-O(6) bond lengths are 2.09 Å. In the second Cu site, Cu(2) is bonded in a distorted square co-planar geometry to two equivalent O(1) and two equivalent O(4) atoms. Both Cu(2)-O(1) bond lengths are 2.04 Å. Both Cu(2)-O(4) bond lengths are 2.19 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Li(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with three equivalent Li(2)O4 tetrahedra. The P(1)-O(1) bond length is 1.56 Å. The P(1)-O(2) bond length is 1.52 Å. The P(1)-O(3) bond length is 1.52 Å. The P(1)-O(5) bond length is 1.64 Å. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with three equivalent Li(1)O4 tetrahedra. The P(2)-O(4) bond length is 1.54 Å. The P(2)-O(5) bond length is 1.63 Å. The P(2)-O(6) bond length is 1.53 Å. The P(2)-O(7) bond length is 1.55 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Li(2), one Li(3), one Cu(2), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Li(2) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Li(1), one Cu(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Li(2), one Li(3), one Cu(2), and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Li(1), one Cu(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to one Li(3), two equivalent Li(1), and one P(2) atom.