Li2S2O7 crystallizes in the orthorhombic Pnma space group. Li(1) is bonded to one O(1), one O(2), one O(5), and two equivalent O(4) atoms to form LiO5 trigonal bipyramids that share corners with two equivalent S(1)O4 tetrahedra, corners with three equivalent S(2)O4 tetrahedra, and edges with two equivalent Li(1)O5 trigonal bipyramids. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SO4 tetrahedra that share  a cornercorner with one S(2)O4 tetrahedra and corners with four equivalent Li(1)O5 trigonal bipyramids. In the second S site, S(2) is bonded to one O(3), one O(5), and two equivalent O(4) atoms to form SO4 tetrahedra that share  a cornercorner with one S(1)O4 tetrahedra and corners with six equivalent Li(1)O5 trigonal bipyramids. There are five inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Li(1) and one S(2) atom. In the second O site, O(5) is bonded in a distorted T-shaped geometry to two equivalent Li(1) and one S(2) atom. In the third O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Li(1) and one S(1) atom. In the fourth O site, O(2) is bonded in a distorted T-shaped geometry to two equivalent Li(1) and one S(1) atom. In the fifth O site, O(3) is bonded in a bent 120 degrees geometry to one S(1) and one S(2) atom.
Li2S2O7 crystallizes in the orthorhombic Pnma space group. Li(1) is bonded to one O(1), one O(2), one O(5), and two equivalent O(4) atoms to form LiO5 trigonal bipyramids that share corners with two equivalent S(1)O4 tetrahedra, corners with three equivalent S(2)O4 tetrahedra, and edges with two equivalent Li(1)O5 trigonal bipyramids. The Li(1)-O(1) bond length is 1.99 Å. The Li(1)-O(2) bond length is 2.10 Å. The Li(1)-O(5) bond length is 2.10 Å. There is one shorter (2.08 Å) and one longer (2.16 Å) Li(1)-O(4) bond length. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SO4 tetrahedra that share  a cornercorner with one S(2)O4 tetrahedra and corners with four equivalent Li(1)O5 trigonal bipyramids. The S(1)-O(2) bond length is 1.46 Å. The S(1)-O(3) bond length is 1.71 Å. Both S(1)-O(1) bond lengths are 1.45 Å. In the second S site, S(2) is bonded to one O(3), one O(5), and two equivalent O(4) atoms to form SO4 tetrahedra that share  a cornercorner with one S(1)O4 tetrahedra and corners with six equivalent Li(1)O5 trigonal bipyramids. The S(2)-O(3) bond length is 1.63 Å. The S(2)-O(5) bond length is 1.46 Å. Both S(2)-O(4) bond lengths are 1.46 Å. There are five inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Li(1) and one S(2) atom. In the second O site, O(5) is bonded in a distorted T-shaped geometry to two equivalent Li(1) and one S(2) atom. In the third O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Li(1) and one S(1) atom. In the fourth O site, O(2) is bonded in a distorted T-shaped geometry to two equivalent Li(1) and one S(1) atom. In the fifth O site, O(3) is bonded in a bent 120 degrees geometry to one S(1) and one S(2) atom.