Fe2C2O7 crystallizes in the monoclinic C2 space group. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), one O(5), one O(7), and one O(9) atom to form corner-sharing FeO4 tetrahedra. In the second Fe site, Fe(2) is bonded to one O(10), one O(3), one O(5), and one O(6) atom to form corner-sharing FeO4 tetrahedra. In the third Fe site, Fe(3) is bonded to one O(1), one O(11), one O(2), and one O(8) atom to form corner-sharing FeO4 tetrahedra. There are three inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(3), one O(8), and one O(9) atom. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(2), one O(4), and one O(6) atom. In the third C site, C(3) is bonded in a trigonal planar geometry to one O(10), one O(11), and one O(7) atom. There are eleven inequivalent O sites. In the first O site, O(6) is bonded in a bent 120 degrees geometry to one Fe(2) and one C(2) atom. In the second O site, O(7) is bonded in a bent 120 degrees geometry to one Fe(1) and one C(3) atom. In the third O site, O(8) is bonded in a bent 120 degrees geometry to one Fe(3) and one C(1) atom. In the fourth O site, O(9) is bonded in a bent 120 degrees geometry to one Fe(1) and one C(1) atom. In the fifth O site, O(10) is bonded in a bent 120 degrees geometry to one Fe(2) and one C(3) atom. In the sixth O site, O(11) is bonded in a bent 120 degrees geometry to one Fe(3) and one C(3) atom. In the seventh O site, O(1) is bonded in a linear geometry to two equivalent Fe(3) atoms. In the eighth O site, O(2) is bonded in a bent 120 degrees geometry to one Fe(3) and one C(2) atom. In the ninth O site, O(3) is bonded in a bent 120 degrees geometry to one Fe(2) and one C(1) atom. In the tenth O site, O(4) is bonded in a bent 120 degrees geometry to one Fe(1) and one C(2) atom. In the eleventh O site, O(5) is bonded in a linear geometry to one Fe(1) and one Fe(2) atom.
Fe2C2O7 crystallizes in the monoclinic C2 space group. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), one O(5), one O(7), and one O(9) atom to form corner-sharing FeO4 tetrahedra. The Fe(1)-O(4) bond length is 1.93 Å. The Fe(1)-O(5) bond length is 1.81 Å. The Fe(1)-O(7) bond length is 1.94 Å. The Fe(1)-O(9) bond length is 1.94 Å. In the second Fe site, Fe(2) is bonded to one O(10), one O(3), one O(5), and one O(6) atom to form corner-sharing FeO4 tetrahedra. The Fe(2)-O(10) bond length is 1.94 Å. The Fe(2)-O(3) bond length is 1.94 Å. The Fe(2)-O(5) bond length is 1.82 Å. The Fe(2)-O(6) bond length is 1.94 Å. In the third Fe site, Fe(3) is bonded to one O(1), one O(11), one O(2), and one O(8) atom to form corner-sharing FeO4 tetrahedra. The Fe(3)-O(1) bond length is 1.80 Å. The Fe(3)-O(11) bond length is 1.94 Å. The Fe(3)-O(2) bond length is 1.94 Å. The Fe(3)-O(8) bond length is 1.94 Å. There are three inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(3), one O(8), and one O(9) atom. The C(1)-O(3) bond length is 1.30 Å. The C(1)-O(8) bond length is 1.29 Å. The C(1)-O(9) bond length is 1.29 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(2), one O(4), and one O(6) atom. The C(2)-O(2) bond length is 1.29 Å. The C(2)-O(4) bond length is 1.29 Å. The C(2)-O(6) bond length is 1.30 Å. In the third C site, C(3) is bonded in a trigonal planar geometry to one O(10), one O(11), and one O(7) atom. The C(3)-O(10) bond length is 1.30 Å. The C(3)-O(11) bond length is 1.29 Å. The C(3)-O(7) bond length is 1.29 Å. There are eleven inequivalent O sites. In the first O site, O(6) is bonded in a bent 120 degrees geometry to one Fe(2) and one C(2) atom. In the second O site, O(7) is bonded in a bent 120 degrees geometry to one Fe(1) and one C(3) atom. In the third O site, O(8) is bonded in a bent 120 degrees geometry to one Fe(3) and one C(1) atom. In the fourth O site, O(9) is bonded in a bent 120 degrees geometry to one Fe(1) and one C(1) atom. In the fifth O site, O(10) is bonded in a bent 120 degrees geometry to one Fe(2) and one C(3) atom. In the sixth O site, O(11) is bonded in a bent 120 degrees geometry to one Fe(3) and one C(3) atom. In the seventh O site, O(1) is bonded in a linear geometry to two equivalent Fe(3) atoms. In the eighth O site, O(2) is bonded in a bent 120 degrees geometry to one Fe(3) and one C(2) atom. In the ninth O site, O(3) is bonded in a bent 120 degrees geometry to one Fe(2) and one C(1) atom. In the tenth O site, O(4) is bonded in a bent 120 degrees geometry to one Fe(1) and one C(2) atom. In the eleventh O site, O(5) is bonded in a linear geometry to one Fe(1) and one Fe(2) atom.