Li2FeCPO7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(4), and one O(5) atom. In the second Li site, Li(2) is bonded to one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form distorted LiO5 trigonal bipyramids that share corners with two equivalent Fe(1)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 66-76°. Fe(1) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form FeO6 octahedra that share corners with four equivalent P(1)O4 tetrahedra, corners with two equivalent Li(2)O5 trigonal bipyramids, and  an edgeedge with one Li(2)O5 trigonal bipyramid. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. P(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra and corners with three equivalent Li(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 38-49°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Li(1), one Fe(1), and one C(1) atom. In the second O site, O(2) is bonded in a trigonal non-coplanar geometry to one Li(1), one Li(2), and one C(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Li(2), one Fe(1), and one C(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Fe(1), and one P(1) 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(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(2), 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(2), one Fe(1), and one P(1) atom.
Li2FeCPO7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(4), and one O(5) atom. The Li(1)-O(1) bond length is 1.97 Å. The Li(1)-O(2) bond length is 2.03 Å. The Li(1)-O(4) bond length is 2.35 Å. The Li(1)-O(5) bond length is 2.04 Å. In the second Li site, Li(2) is bonded to one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form distorted LiO5 trigonal bipyramids that share corners with two equivalent Fe(1)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 66-76°. The Li(2)-O(2) bond length is 1.95 Å. The Li(2)-O(3) bond length is 2.35 Å. The Li(2)-O(4) bond length is 2.12 Å. The Li(2)-O(6) bond length is 2.12 Å. The Li(2)-O(7) bond length is 2.18 Å. Fe(1) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form FeO6 octahedra that share corners with four equivalent P(1)O4 tetrahedra, corners with two equivalent Li(2)O5 trigonal bipyramids, and  an edgeedge with one Li(2)O5 trigonal bipyramid. The Fe(1)-O(1) bond length is 2.19 Å. The Fe(1)-O(3) bond length is 2.04 Å. The Fe(1)-O(4) bond length is 2.11 Å. The Fe(1)-O(5) bond length is 1.99 Å. The Fe(1)-O(6) bond length is 1.99 Å. The Fe(1)-O(7) bond length is 1.99 Å. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. The C(1)-O(1) bond length is 1.32 Å. The C(1)-O(2) bond length is 1.27 Å. The C(1)-O(3) bond length is 1.31 Å. P(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra and corners with three equivalent Li(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 38-49°. The P(1)-O(4) bond length is 1.55 Å. The P(1)-O(5) bond length is 1.56 Å. The P(1)-O(6) bond length is 1.54 Å. The P(1)-O(7) bond length is 1.56 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Li(1), one Fe(1), and one C(1) atom. In the second O site, O(2) is bonded in a trigonal non-coplanar geometry to one Li(1), one Li(2), and one C(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Li(2), one Fe(1), and one C(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Fe(1), and one P(1) 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(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(2), 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(2), one Fe(1), and one P(1) atom.