Li2SnP2O7 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 distorted rectangular see-saw-like geometry to one O(5), one O(7), and two equivalent O(2) atoms. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form distorted LiO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. Sn(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(5), 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(3), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with two equivalent Li(2)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with three equivalent Li(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 Li(2) and one P(2) atom. In the second O site, O(2) is bonded to one Li(2), two equivalent Li(1), and one P(1) atom to form distorted OLi3P trigonal pyramids that share corners with three equivalent O(5)Li2SnP tetrahedra and  an edgeedge with one O(2)Li3P trigonal pyramid. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Li(2), one Sn(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Li(2), one Sn(1), and one P(2) atom. In the fifth O site, O(5) is bonded to one Li(1), one Li(2), one Sn(1), and one P(2) atom to form distorted corner-sharing OLi2SnP tetrahedra. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Li(1), one Sn(1), and one P(1) 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 in a distorted rectangular see-saw-like geometry to one O(5), one O(7), and two equivalent O(2) atoms. The Li(1)-O(5) bond length is 2.08 Å. The Li(1)-O(7) bond length is 2.08 Å. There is one shorter (2.08 Å) and one longer (2.27 Å) Li(1)-O(2) bond length. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form distorted LiO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. The Li(2)-O(1) bond length is 1.96 Å. The Li(2)-O(2) bond length is 2.11 Å. The Li(2)-O(3) bond length is 2.29 Å. The Li(2)-O(4) bond length is 2.25 Å. The Li(2)-O(5) bond length is 2.23 Å. Sn(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(5), and one O(7) atom. The Sn(1)-O(3) bond length is 2.21 Å. The Sn(1)-O(4) bond length is 2.71 Å. The Sn(1)-O(5) bond length is 2.28 Å. The Sn(1)-O(7) bond length is 2.33 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with two equivalent Li(2)O5 trigonal bipyramids. The P(1)-O(2) bond length is 1.52 Å. The P(1)-O(3) bond length is 1.55 Å. The P(1)-O(6) bond length is 1.63 Å. The P(1)-O(7) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with three equivalent Li(2)O5 trigonal bipyramids. The P(2)-O(1) bond length is 1.52 Å. The P(2)-O(4) bond length is 1.52 Å. The P(2)-O(5) bond length is 1.58 Å. The P(2)-O(6) bond length is 1.64 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Li(2) and one P(2) atom. In the second O site, O(2) is bonded to one Li(2), two equivalent Li(1), and one P(1) atom to form distorted OLi3P trigonal pyramids that share corners with three equivalent O(5)Li2SnP tetrahedra and  an edgeedge with one O(2)Li3P trigonal pyramid. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Li(2), one Sn(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Li(2), one Sn(1), and one P(2) atom. In the fifth O site, O(5) is bonded to one Li(1), one Li(2), one Sn(1), and one P(2) atom to form distorted corner-sharing OLi2SnP tetrahedra. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Li(1), one Sn(1), and one P(1) atom.