Li2Fe2C2O7 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 distorted trigonal planar geometry to one O(3), one O(6), and one O(7) atom. In the second Li site, Li(2) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms to form distorted face-sharing LiO6 octahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), and two equivalent O(1) atoms. In the second Fe site, Fe(2) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(2), one O(5), and one O(7) atom. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(3), one O(4), and one O(6) atom. There are seven inequivalent O sites. In the first O site, O(7) is bonded to one Li(1), two equivalent Li(2), and one C(1) atom to form distorted corner-sharing OLi3C trigonal pyramids. In the second O site, O(1) is bonded in a distorted see-saw-like geometry to two equivalent Fe(1) and two equivalent Fe(2) atoms. In the third O site, O(2) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one C(1) atom. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to one Li(1), one Fe(1), one Fe(2), and one C(2) atom. In the fifth O site, O(4) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one C(2) atom. In the sixth O site, O(5) is bonded in a 1-coordinate geometry to two equivalent Li(2), one Fe(2), and one C(1) atom. In the seventh O site, O(6) is bonded in a 4-coordinate geometry to one Li(1), two equivalent Li(2), and one C(2) atom.
Li2Fe2C2O7 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 distorted trigonal planar geometry to one O(3), one O(6), and one O(7) atom. The Li(1)-O(3) bond length is 1.94 Å. The Li(1)-O(6) bond length is 1.89 Å. The Li(1)-O(7) bond length is 1.96 Å. In the second Li site, Li(2) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms to form distorted face-sharing LiO6 octahedra. There is one shorter (2.19 Å) and one longer (2.50 Å) Li(2)-O(5) bond length. There is one shorter (2.10 Å) and one longer (2.47 Å) Li(2)-O(6) bond length. There is one shorter (2.15 Å) and one longer (2.24 Å) Li(2)-O(7) bond length. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), and two equivalent O(1) atoms. The Fe(1)-O(2) bond length is 2.23 Å. The Fe(1)-O(3) bond length is 2.70 Å. The Fe(1)-O(4) bond length is 2.18 Å. There is one shorter (1.95 Å) and one longer (1.97 Å) Fe(1)-O(1) bond length. In the second Fe site, Fe(2) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms. The Fe(2)-O(2) bond length is 2.12 Å. The Fe(2)-O(3) bond length is 2.19 Å. The Fe(2)-O(4) bond length is 2.23 Å. The Fe(2)-O(5) bond length is 2.42 Å. There is one shorter (2.04 Å) and one longer (2.30 Å) Fe(2)-O(1) bond length. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(2), one O(5), and one O(7) atom. The C(1)-O(2) bond length is 1.31 Å. The C(1)-O(5) bond length is 1.30 Å. The C(1)-O(7) bond length is 1.30 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(3), one O(4), and one O(6) atom. The C(2)-O(3) bond length is 1.31 Å. The C(2)-O(4) bond length is 1.29 Å. The C(2)-O(6) bond length is 1.29 Å. There are seven inequivalent O sites. In the first O site, O(7) is bonded to one Li(1), two equivalent Li(2), and one C(1) atom to form distorted corner-sharing OLi3C trigonal pyramids. In the second O site, O(1) is bonded in a distorted see-saw-like geometry to two equivalent Fe(1) and two equivalent Fe(2) atoms. In the third O site, O(2) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one C(1) atom. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to one Li(1), one Fe(1), one Fe(2), and one C(2) atom. In the fifth O site, O(4) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one C(2) atom. In the sixth O site, O(5) is bonded in a 1-coordinate geometry to two equivalent Li(2), one Fe(2), and one C(1) atom. In the seventh O site, O(6) is bonded in a 4-coordinate geometry to one Li(1), two equivalent Li(2), and one C(2) atom.