Li2SnP2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), one O(7), and two equivalent O(6) atoms to form LiO5 trigonal bipyramids that share  a cornercorner with one Li(2)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Li(1)O5 trigonal bipyramid. In the second Li site, Li(2) is bonded to one O(2), one O(3), and two equivalent O(5) atoms to form LiO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra,  a cornercorner with one Li(1)O5 trigonal bipyramid, and  an edgeedge with one Li(2)O4 tetrahedra. Sn(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(7) atom. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent Li(2)O4 tetrahedra, and corners with three equivalent Li(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(3), one O(4), 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 two equivalent Li(1)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Li(1), one Sn(1), and one P(2) atom. In the second O site, O(2) is bonded in a distorted tetrahedral geometry to one Li(1), one Li(2), one Sn(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(2), one Sn(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Li(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Li(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Li(1), one Sn(1), and one P(2) atom.
Li2SnP2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), one O(7), and two equivalent O(6) atoms to form LiO5 trigonal bipyramids that share  a cornercorner with one Li(2)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Li(1)O5 trigonal bipyramid. The Li(1)-O(1) bond length is 2.27 Å. The Li(1)-O(2) bond length is 2.34 Å. The Li(1)-O(7) bond length is 2.03 Å. There is one shorter (1.98 Å) and one longer (2.20 Å) Li(1)-O(6) bond length. In the second Li site, Li(2) is bonded to one O(2), one O(3), and two equivalent O(5) atoms to form LiO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra,  a cornercorner with one Li(1)O5 trigonal bipyramid, and  an edgeedge with one Li(2)O4 tetrahedra. The Li(2)-O(2) bond length is 2.07 Å. The Li(2)-O(3) bond length is 1.99 Å. There is one shorter (2.00 Å) and one longer (2.01 Å) Li(2)-O(5) bond length. Sn(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(7) atom. The Sn(1)-O(1) bond length is 2.33 Å. The Sn(1)-O(2) bond length is 2.44 Å. The Sn(1)-O(3) bond length is 2.34 Å. The Sn(1)-O(7) bond length is 2.65 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent Li(2)O4 tetrahedra, and corners with three equivalent Li(1)O5 trigonal bipyramids. The P(1)-O(2) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.64 Å. The P(1)-O(5) bond length is 1.53 Å. The P(1)-O(6) bond length is 1.52 Å. In the second P site, P(2) is bonded to one O(1), one O(3), one O(4), 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 two equivalent Li(1)O5 trigonal bipyramids. The P(2)-O(1) bond length is 1.55 Å. The P(2)-O(3) bond length is 1.55 Å. The P(2)-O(4) bond length is 1.62 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 distorted trigonal planar geometry to one Li(1), one Sn(1), and one P(2) atom. In the second O site, O(2) is bonded in a distorted tetrahedral geometry to one Li(1), one Li(2), one Sn(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(2), one Sn(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Li(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Li(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Li(1), one Sn(1), and one P(2) atom.