Co2C2O7 crystallizes in the monoclinic C2 space group. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(11), one O(2), and one O(8) atom to form corner-sharing CoO4 tetrahedra. In the second Co site, Co(2) is bonded to one O(4), one O(5), one O(7), and one O(9) atom to form corner-sharing CoO4 tetrahedra. In the third Co site, Co(3) is bonded to one O(10), one O(3), one O(5), and one O(6) atom to form corner-sharing CoO4 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(9) is bonded in a bent 120 degrees geometry to one Co(2) and one C(1) atom. In the second O site, O(10) is bonded in a bent 120 degrees geometry to one Co(3) and one C(3) atom. In the third O site, O(11) is bonded in a bent 120 degrees geometry to one Co(1) and one C(3) atom. In the fourth O site, O(1) is bonded in a linear geometry to two equivalent Co(1) atoms. In the fifth O site, O(2) is bonded in a bent 120 degrees geometry to one Co(1) and one C(2) atom. In the sixth O site, O(3) is bonded in a bent 120 degrees geometry to one Co(3) and one C(1) atom. In the seventh O site, O(4) is bonded in a bent 120 degrees geometry to one Co(2) and one C(2) atom. In the eighth O site, O(5) is bonded in a linear geometry to one Co(2) and one Co(3) atom. In the ninth O site, O(6) is bonded in a bent 120 degrees geometry to one Co(3) and one C(2) atom. In the tenth O site, O(7) is bonded in a bent 120 degrees geometry to one Co(2) and one C(3) atom. In the eleventh O site, O(8) is bonded in a bent 120 degrees geometry to one Co(1) and one C(1) atom.
Co2C2O7 crystallizes in the monoclinic C2 space group. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(11), one O(2), and one O(8) atom to form corner-sharing CoO4 tetrahedra. The Co(1)-O(1) bond length is 1.78 Å. The Co(1)-O(11) bond length is 1.90 Å. The Co(1)-O(2) bond length is 1.89 Å. The Co(1)-O(8) bond length is 1.89 Å. In the second Co site, Co(2) is bonded to one O(4), one O(5), one O(7), and one O(9) atom to form corner-sharing CoO4 tetrahedra. The Co(2)-O(4) bond length is 1.90 Å. The Co(2)-O(5) bond length is 1.77 Å. The Co(2)-O(7) bond length is 1.89 Å. The Co(2)-O(9) bond length is 1.92 Å. In the third Co site, Co(3) is bonded to one O(10), one O(3), one O(5), and one O(6) atom to form corner-sharing CoO4 tetrahedra. The Co(3)-O(10) bond length is 1.91 Å. The Co(3)-O(3) bond length is 1.89 Å. The Co(3)-O(5) bond length is 1.80 Å. The Co(3)-O(6) bond length is 1.91 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 1.31 Å. The C(1)-O(8) bond length is 1.29 Å. The C(1)-O(9) bond length is 1.28 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(9) is bonded in a bent 120 degrees geometry to one Co(2) and one C(1) atom. In the second O site, O(10) is bonded in a bent 120 degrees geometry to one Co(3) and one C(3) atom. In the third O site, O(11) is bonded in a bent 120 degrees geometry to one Co(1) and one C(3) atom. In the fourth O site, O(1) is bonded in a linear geometry to two equivalent Co(1) atoms. In the fifth O site, O(2) is bonded in a bent 120 degrees geometry to one Co(1) and one C(2) atom. In the sixth O site, O(3) is bonded in a bent 120 degrees geometry to one Co(3) and one C(1) atom. In the seventh O site, O(4) is bonded in a bent 120 degrees geometry to one Co(2) and one C(2) atom. In the eighth O site, O(5) is bonded in a linear geometry to one Co(2) and one Co(3) atom. In the ninth O site, O(6) is bonded in a bent 120 degrees geometry to one Co(3) and one C(2) atom. In the tenth O site, O(7) is bonded in a bent 120 degrees geometry to one Co(2) and one C(3) atom. In the eleventh O site, O(8) is bonded in a bent 120 degrees geometry to one Co(1) and one C(1) atom.