Li2CuP2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(5), and one O(7) atom. In the second Li site, Li(2) is bonded in a 1-coordinate geometry to one O(3) atom. Cu(1) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(6), and two equivalent O(2) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(6), and one O(7) atom. In the second P site, P(2) is bonded in a 3-coordinate geometry to one O(3), one O(4), one O(5), and one O(7) atom. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Cu(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Cu(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Li(2), and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Li(1), one Cu(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one Li(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Cu(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Li(1), one P(1), and one P(2) atom.
Li2CuP2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(5), and one O(7) atom. The Li(1)-O(3) bond length is 1.72 Å. The Li(1)-O(4) bond length is 2.28 Å. The Li(1)-O(5) bond length is 2.02 Å. The Li(1)-O(7) bond length is 2.20 Å. In the second Li site, Li(2) is bonded in a 1-coordinate geometry to one O(3) atom. The Li(2)-O(3) bond length is 1.61 Å. Cu(1) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(6), and two equivalent O(2) atoms. The Cu(1)-O(1) bond length is 2.27 Å. The Cu(1)-O(4) bond length is 2.17 Å. The Cu(1)-O(6) bond length is 2.33 Å. There is one shorter (2.22 Å) and one longer (2.31 Å) Cu(1)-O(2) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(6), and one O(7) atom. The P(1)-O(1) bond length is 1.27 Å. The P(1)-O(2) bond length is 1.46 Å. The P(1)-O(6) bond length is 1.87 Å. The P(1)-O(7) bond length is 2.06 Å. In the second P site, P(2) is bonded in a 3-coordinate geometry to one O(3), one O(4), one O(5), and one O(7) atom. The P(2)-O(3) bond length is 1.51 Å. The P(2)-O(4) bond length is 1.28 Å. The P(2)-O(5) bond length is 1.59 Å. The P(2)-O(7) bond length is 2.27 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Cu(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Cu(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Li(2), and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Li(1), one Cu(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one Li(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Cu(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Li(1), one P(1), and one P(2) atom.