Li3Sn2P5O16 crystallizes in the monoclinic P2/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(3), one O(4), and two equivalent O(8) atoms to form LiO5 trigonal bipyramids that share corners with three equivalent Sn(1)O5 square pyramids, corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(3)O4 tetrahedra, and  an edgeedge with one Li(1)O5 trigonal bipyramid. In the second Li site, Li(2) is bonded in a see-saw-like geometry to two equivalent O(2) and two equivalent O(5) atoms. Sn(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form distorted SnO5 square pyramids that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and corners with three equivalent Li(1)O5 trigonal bipyramids. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Sn(1)O5 square pyramids,  a cornercorner with one P(3)O4 tetrahedra, and corners with two equivalent Li(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to two equivalent O(2) and two equivalent O(6) atoms to form PO4 tetrahedra that share corners with two equivalent Sn(1)O5 square pyramids and corners with two equivalent P(3)O4 tetrahedra. In the third P site, P(3) is bonded to one O(3), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Sn(1)O5 square pyramid,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with three equivalent Li(1)O5 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(8) is bonded in a distorted trigonal planar geometry to two equivalent Li(1) and one P(3) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Li(1), one Sn(1), and one P(1) atom. In the third O site, O(2) is bonded in a 3-coordinate geometry to one Li(2), one Sn(1), and one P(2) atom. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to one Li(1), one Sn(1), and one P(3) atom. In the fifth O site, O(4) is bonded in a 3-coordinate geometry to one Li(1), one Sn(1), and one P(1) atom. In the sixth O site, O(5) is bonded in a 3-coordinate geometry to one Li(2), one Sn(1), and one P(1) atom. In the seventh O site, O(6) is bonded in a bent 150 degrees geometry to one P(2) and one P(3) atom. In the eighth O site, O(7) is bonded in a bent 120 degrees geometry to one P(1) and one P(3) atom.
Li3Sn2P5O16 crystallizes in the monoclinic P2/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(3), one O(4), and two equivalent O(8) atoms to form LiO5 trigonal bipyramids that share corners with three equivalent Sn(1)O5 square pyramids, corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(3)O4 tetrahedra, and  an edgeedge with one Li(1)O5 trigonal bipyramid. The Li(1)-O(1) bond length is 2.08 Å. The Li(1)-O(3) bond length is 2.29 Å. The Li(1)-O(4) bond length is 2.13 Å. There is one shorter (2.09 Å) and one longer (2.20 Å) Li(1)-O(8) bond length. In the second Li site, Li(2) is bonded in a see-saw-like geometry to two equivalent O(2) and two equivalent O(5) atoms. Both Li(2)-O(2) bond lengths are 1.92 Å. Both Li(2)-O(5) bond lengths are 2.30 Å. Sn(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form distorted SnO5 square pyramids that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and corners with three equivalent Li(1)O5 trigonal bipyramids. The Sn(1)-O(1) bond length is 2.51 Å. The Sn(1)-O(2) bond length is 2.54 Å. The Sn(1)-O(3) bond length is 2.37 Å. The Sn(1)-O(4) bond length is 2.64 Å. The Sn(1)-O(5) bond length is 2.39 Å. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Sn(1)O5 square pyramids,  a cornercorner with one P(3)O4 tetrahedra, and corners with two equivalent Li(1)O5 trigonal bipyramids. The P(1)-O(1) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.52 Å. The P(1)-O(5) bond length is 1.54 Å. The P(1)-O(7) bond length is 1.65 Å. In the second P site, P(2) is bonded to two equivalent O(2) and two equivalent O(6) atoms to form PO4 tetrahedra that share corners with two equivalent Sn(1)O5 square pyramids and corners with two equivalent P(3)O4 tetrahedra. Both P(2)-O(2) bond lengths are 1.50 Å. Both P(2)-O(6) bond lengths are 1.59 Å. In the third P site, P(3) is bonded to one O(3), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Sn(1)O5 square pyramid,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with three equivalent Li(1)O5 trigonal bipyramids. The P(3)-O(3) bond length is 1.52 Å. The P(3)-O(6) bond length is 1.59 Å. The P(3)-O(7) bond length is 1.61 Å. The P(3)-O(8) bond length is 1.51 Å. There are eight inequivalent O sites. In the first O site, O(8) is bonded in a distorted trigonal planar geometry to two equivalent Li(1) and one P(3) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Li(1), one Sn(1), and one P(1) atom. In the third O site, O(2) is bonded in a 3-coordinate geometry to one Li(2), one Sn(1), and one P(2) atom. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to one Li(1), one Sn(1), and one P(3) atom. In the fifth O site, O(4) is bonded in a 3-coordinate geometry to one Li(1), one Sn(1), and one P(1) atom. In the sixth O site, O(5) is bonded in a 3-coordinate geometry to one Li(2), one Sn(1), and one P(1) atom. In the seventh O site, O(6) is bonded in a bent 150 degrees geometry to one P(2) and one P(3) atom. In the eighth O site, O(7) is bonded in a bent 120 degrees geometry to one P(1) and one P(3) atom.