Li2Fe3(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form LiO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with three equivalent Fe(1)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form FeO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent Li(1)O4 tetrahedra, and corners with three equivalent P(2)O4 tetrahedra. In the second Fe site, Fe(2) is bonded in a square co-planar geometry to two equivalent O(5) and two equivalent O(6) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Li(1)O4 tetrahedra. In the second P site, P(2) 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(1)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, and corners with three equivalent Fe(1)O4 tetrahedra. 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 Fe(1), and one P(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(2), and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Li(1), one Fe(1), and one P(1) atom.
Li2Fe3(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form LiO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with three equivalent Fe(1)O4 tetrahedra. The Li(1)-O(1) bond length is 2.01 Å. The Li(1)-O(3) bond length is 2.21 Å. The Li(1)-O(5) bond length is 2.03 Å. The Li(1)-O(7) bond length is 2.22 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form FeO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent Li(1)O4 tetrahedra, and corners with three equivalent P(2)O4 tetrahedra. The Fe(1)-O(1) bond length is 2.01 Å. The Fe(1)-O(3) bond length is 2.09 Å. The Fe(1)-O(4) bond length is 1.96 Å. The Fe(1)-O(7) bond length is 2.04 Å. In the second Fe site, Fe(2) is bonded in a square co-planar geometry to two equivalent O(5) and two equivalent O(6) atoms. Both Fe(2)-O(5) bond lengths are 2.06 Å. Both Fe(2)-O(6) bond lengths are 2.00 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Li(1)O4 tetrahedra. The P(1)-O(2) bond length is 1.63 Å. The P(1)-O(5) bond length is 1.54 Å. The P(1)-O(6) bond length is 1.51 Å. The P(1)-O(7) bond length is 1.55 Å. In the second P site, P(2) 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(1)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, and corners with three equivalent Fe(1)O4 tetrahedra. The P(2)-O(1) bond length is 1.54 Å. The P(2)-O(2) bond length is 1.60 Å. The P(2)-O(3) bond length is 1.55 Å. The P(2)-O(4) 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 Fe(1), and one P(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(2), and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Li(1), one Fe(1), and one P(1) atom.