LiFeP2O7 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and two equivalent O(7) atoms. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form FeO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) 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(2)O4 tetrahedra and corners with three equivalent Fe(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Fe(1)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Li(1), one Fe(1), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate 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(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(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(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to two equivalent Li(1) and one P(2) atom.
LiFeP2O7 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and two equivalent O(7) atoms. The Li(1)-O(1) bond length is 2.62 Å. The Li(1)-O(2) bond length is 2.53 Å. The Li(1)-O(3) bond length is 2.22 Å. The Li(1)-O(5) bond length is 2.05 Å. There is one shorter (1.94 Å) and one longer (2.11 Å) Li(1)-O(7) bond length. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form FeO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. The Fe(1)-O(1) bond length is 1.99 Å. The Fe(1)-O(2) bond length is 1.95 Å. The Fe(1)-O(3) bond length is 1.99 Å. The Fe(1)-O(5) bond length is 2.02 Å. The Fe(1)-O(6) bond length is 1.93 Å. There are two inequivalent P sites. In the first P site, P(1) 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(2)O4 tetrahedra and corners with three equivalent Fe(1)O5 trigonal bipyramids. The P(1)-O(1) bond length is 1.53 Å. The P(1)-O(2) bond length is 1.55 Å. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.58 Å. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Fe(1)O5 trigonal bipyramids. The P(2)-O(4) bond length is 1.63 Å. The P(2)-O(5) bond length is 1.55 Å. The P(2)-O(6) bond length is 1.54 Å. The P(2)-O(7) bond length is 1.50 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Li(1), one Fe(1), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate 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(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(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(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to two equivalent Li(1) and one P(2) atom.