LiFeP2O7 crystallizes in the monoclinic C2/c space group. Li(1) is bonded to one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form distorted LiO5 square pyramids that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 67°. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form FeO6 octahedra that share  a cornercorner with one Li(1)O5 square pyramid, corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and edges with two equivalent Li(1)O5 square pyramids. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Li(1)O5 square pyramids, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-55°. In the second P site, P(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with two equivalent Li(1)O5 square pyramids, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 40-55°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(1) 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 distorted bent 120 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(1) atom.
LiFeP2O7 crystallizes in the monoclinic C2/c space group. Li(1) is bonded to one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form distorted LiO5 square pyramids that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 67°. The Li(1)-O(2) bond length is 2.12 Å. The Li(1)-O(3) bond length is 2.19 Å. The Li(1)-O(5) bond length is 2.36 Å. The Li(1)-O(6) bond length is 2.36 Å. The Li(1)-O(7) bond length is 2.13 Å. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form FeO6 octahedra that share  a cornercorner with one Li(1)O5 square pyramid, corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and edges with two equivalent Li(1)O5 square pyramids. The Fe(1)-O(1) bond length is 1.98 Å. The Fe(1)-O(2) bond length is 2.07 Å. The Fe(1)-O(3) bond length is 2.02 Å. The Fe(1)-O(5) bond length is 2.11 Å. The Fe(1)-O(6) bond length is 2.02 Å. The Fe(1)-O(7) bond length is 2.04 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(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Li(1)O5 square pyramids, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-55°. The P(1)-O(2) bond length is 1.53 Å. The P(1)-O(4) bond length is 1.60 Å. The P(1)-O(6) bond length is 1.54 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(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with two equivalent Li(1)O5 square pyramids, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 40-55°. The P(2)-O(1) bond length is 1.52 Å. The P(2)-O(3) bond length is 1.53 Å. The P(2)-O(4) bond length is 1.63 Å. The P(2)-O(5) bond length is 1.54 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(1) 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 distorted bent 120 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(1) atom.