Co(C2O)4 crystallizes in the monoclinic C2/c space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a distorted tetrahedral geometry to one O(1), one O(2), one O(4), and one O(7) atom. The Co(1)-O(1) bond length is 1.96 Å. The Co(1)-O(2) bond length is 1.98 Å. The Co(1)-O(4) bond length is 2.00 Å. The Co(1)-O(7) bond length is 1.96 Å. In the second Co site, Co(2) is bonded in a 1-coordinate geometry to one Co(2), one O(3), and two equivalent O(5) atoms. The Co(2)-Co(2) bond length is 0.25 Å. The Co(2)-O(3) bond length is 1.92 Å. There is one shorter (2.03 Å) and one longer (2.06 Å) Co(2)-O(5) bond length. There are sixteen inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one C(12), one C(4), and one C(5) atom. The C(1)-C(12) bond length is 1.39 Å. The C(1)-C(4) bond length is 1.51 Å. The C(1)-C(5) bond length is 1.39 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one C(8), one O(2), and one O(5) atom. The C(2)-C(8) bond length is 1.49 Å. The C(2)-O(2) bond length is 1.26 Å. The C(2)-O(5) bond length is 1.25 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one C(10), one O(1), and one O(3) atom. The C(3)-C(10) bond length is 1.50 Å. The C(3)-O(1) bond length is 1.27 Å. The C(3)-O(3) bond length is 1.24 Å. In the fourth C site, C(4) is bonded in a bent 120 degrees geometry to one C(1), one O(4), and one O(6) atom. The C(4)-O(4) bond length is 1.32 Å. The C(4)-O(6) bond length is 1.22 Å. In the fifth C site, C(5) is bonded in a bent 120 degrees geometry to one C(1) and one C(12) atom. The C(5)-C(12) bond length is 1.37 Å. In the sixth C site, C(6) is bonded in a bent 120 degrees geometry to one C(11) and one C(8) atom. The C(6)-C(11) bond length is 1.39 Å. The C(6)-C(8) bond length is 1.40 Å. In the seventh C site, C(7) is bonded in a distorted bent 120 degrees geometry to one C(10) and one C(9) atom. The C(7)-C(10) bond length is 1.38 Å. The C(7)-C(9) bond length is 1.40 Å. In the eighth C site, C(8) is bonded in a trigonal planar geometry to one C(2), one C(6), and one C(9) atom. The C(8)-C(9) bond length is 1.38 Å. In the ninth C site, C(9) is bonded in a bent 120 degrees geometry to one C(7) and one C(8) atom. In the tenth C site, C(10) is bonded in a trigonal planar geometry to one C(11), one C(3), and one C(7) atom. The C(10)-C(11) bond length is 1.39 Å. In the eleventh C site, C(11) is bonded in a bent 120 degrees geometry to one C(10) and one C(6) atom. In the twelfth C site, C(12) is bonded in a bent 120 degrees geometry to one C(1) and one C(5) atom. In the thirteenth C site, C(13) is bonded in a trigonal planar geometry to one C(14), one C(15), and one C(16) atom. The C(13)-C(14) bond length is 1.55 Å. The C(13)-C(15) bond length is 1.36 Å. The C(13)-C(16) bond length is 1.37 Å. In the fourteenth C site, C(14) is bonded in a bent 120 degrees geometry to one C(13), one O(7), and one O(8) atom. The C(14)-O(7) bond length is 1.14 Å. The C(14)-O(8) bond length is 1.28 Å. In the fifteenth C site, C(15) is bonded in a single-bond geometry to one C(13) and one C(16) atom. The C(15)-C(16) bond length is 1.40 Å. In the sixteenth C site, C(16) is bonded in a distorted bent 120 degrees geometry to one C(13) and one C(15) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Co(1) and one C(3) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Co(1) and one C(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Co(2) and one C(3) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Co(1) and one C(4) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Co(2) and one C(2) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one C(4) atom. In the seventh O site, O(7) is bonded in a water-like geometry to one Co(1) and one C(14) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one C(14) atom. Linkers: 16 [O]C(=O)c1[c][c]c(C([O])=O)[c][c]1. Metal clusters: 4 O=[C]O[Co]1(O[C]=O)O[C]O[Co]O[C]O1.O=[C]O[Co]1(O[C]=O)O[C]O[Co]O[C]O1. RCSR code: bcg. The MOF has largest included sphere 7.33 A, density 0.99 g/cm3, surface area 3584.93 m2/g, accessible volume 0.63 cm3/g