Na2LiCuP2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom. In the second Na site, Na(2) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form distorted NaO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. Li(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one O(6), and one O(7) atom. Cu(1) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(5), and one O(6) atom. 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(4) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with three equivalent Na(2)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Na(2)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one Na(1), one Na(2), one Li(1), one Cu(1), and one P(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one Na(1), one Na(2), one Li(1), one Cu(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Li(1), one Cu(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted tetrahedral geometry to one Na(1), one Li(1), one Cu(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Li(1), and one P(2) atom.
Na2LiCuP2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom. The Na(1)-O(2) bond length is 2.76 Å. The Na(1)-O(3) bond length is 2.44 Å. The Na(1)-O(4) bond length is 2.25 Å. The Na(1)-O(5) bond length is 2.50 Å. The Na(1)-O(6) bond length is 2.53 Å. The Na(1)-O(7) bond length is 2.48 Å. In the second Na site, Na(2) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form distorted NaO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. The Na(2)-O(2) bond length is 2.40 Å. The Na(2)-O(3) bond length is 2.43 Å. The Na(2)-O(4) bond length is 2.34 Å. The Na(2)-O(5) bond length is 2.52 Å. The Na(2)-O(7) bond length is 2.43 Å. Li(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one O(6), and one O(7) atom. The Li(1)-O(2) bond length is 2.47 Å. The Li(1)-O(3) bond length is 2.53 Å. The Li(1)-O(5) bond length is 2.26 Å. The Li(1)-O(6) bond length is 1.98 Å. The Li(1)-O(7) bond length is 1.93 Å. Cu(1) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(5), and one O(6) atom. The Cu(1)-O(2) bond length is 2.09 Å. The Cu(1)-O(3) bond length is 2.13 Å. The Cu(1)-O(5) bond length is 2.37 Å. The Cu(1)-O(6) bond length is 2.13 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(4) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with three equivalent Na(2)O5 trigonal bipyramids. The P(1)-O(1) bond length is 1.64 Å. The P(1)-O(2) bond length is 1.55 Å. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.52 Å. In the second P site, P(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Na(2)O5 trigonal bipyramids. The P(2)-O(1) bond length is 1.63 Å. The P(2)-O(5) bond length is 1.55 Å. The P(2)-O(6) bond length is 1.56 Å. The P(2)-O(7) bond length is 1.52 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one Na(1), one Na(2), one Li(1), one Cu(1), and one P(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one Na(1), one Na(2), one Li(1), one Cu(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Li(1), one Cu(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted tetrahedral geometry to one Na(1), one Li(1), one Cu(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Li(1), and one P(2) atom.