Na2Co3H18(C2O)24 crystallizes in the orthorhombic Fddd space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(3), two equivalent O(7), and two equivalent O(8) atoms. Both Na(1)-O(3) bond lengths are 2.42 Å. Both Na(1)-O(7) bond lengths are 2.72 Å. Both Na(1)-O(8) bond lengths are 2.34 Å. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to four equivalent O(7) atoms. All Na(2)-O(7) bond lengths are 2.36 Å. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to four equivalent O(12) atoms. All Na(3)-O(12) bond lengths are 2.32 Å. 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(3), and one O(4) atom. The Co(1)-O(1) bond length is 1.93 Å. The Co(1)-O(2) bond length is 1.95 Å. The Co(1)-O(3) bond length is 1.98 Å. The Co(1)-O(4) bond length is 1.96 Å. In the second Co site, Co(2) is bonded in a 6-coordinate geometry to two equivalent O(10), two equivalent O(11), and two equivalent O(12) atoms. Both Co(2)-O(10) bond lengths are 2.28 Å. Both Co(2)-O(11) bond lengths are 1.98 Å. Both Co(2)-O(12) bond lengths are 2.40 Å. There are twenty-four inequivalent C sites. In the first C site, C(17) is bonded in a distorted single-bond geometry to one C(11) and one H(7) atom. The C(17)-C(11) bond length is 1.39 Å. The C(17)-H(7) bond length is 0.95 Å. In the second C site, C(18) is bonded in a trigonal planar geometry to one C(12), one C(23), and one C(24) atom. The C(18)-C(12) bond length is 1.39 Å. The C(18)-C(23) bond length is 1.39 Å. The C(18)-C(24) bond length is 1.51 Å. In the third C site, C(19) is bonded in a trigonal planar geometry to one C(13), one C(14), and one C(19) atom. The C(19)-C(13) bond length is 1.39 Å. The C(19)-C(14) bond length is 1.39 Å. The C(19)-C(19) bond length is 1.50 Å. In the fourth C site, C(20) is bonded in a distorted bent 120 degrees geometry to one C(13), one O(10), and one O(12) atom. The C(20)-C(13) bond length is 1.51 Å. The C(20)-O(10) bond length is 1.18 Å. The C(20)-O(12) bond length is 1.21 Å. In the fifth C site, C(21) is bonded in a distorted trigonal planar geometry to one C(15), one C(16), and one H(8) atom. The C(21)-C(15) bond length is 1.38 Å. The C(21)-C(16) bond length is 1.41 Å. The C(21)-H(8) bond length is 0.95 Å. In the sixth C site, C(22) is bonded in a distorted bent 120 degrees geometry to one C(16), one O(11), and one O(9) atom. The C(22)-C(16) bond length is 1.50 Å. The C(22)-O(11) bond length is 1.27 Å. The C(22)-O(9) bond length is 1.24 Å. In the seventh C site, C(23) is bonded in a distorted single-bond geometry to one C(18) and one H(9) atom. The C(23)-H(9) bond length is 0.95 Å. In the eighth C site, C(24) is bonded in a distorted bent 120 degrees geometry to one C(18), one O(4), and one O(8) atom. The C(24)-O(4) bond length is 1.28 Å. The C(24)-O(8) bond length is 1.23 Å. In the ninth C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(4), one O(1), and one O(5) atom. The C(1)-C(4) bond length is 1.51 Å. The C(1)-O(1) bond length is 1.25 Å. The C(1)-O(5) bond length is 1.23 Å. In the tenth C site, C(2) is bonded in a distorted bent 120 degrees geometry to one C(5), one O(2), and one O(6) atom. The C(2)-C(5) bond length is 1.50 Å. The C(2)-O(2) bond length is 1.28 Å. The C(2)-O(6) bond length is 1.24 Å. In the eleventh C site, C(3) is bonded in a distorted bent 120 degrees geometry to one C(6), one O(3), and one O(7) atom. The C(3)-C(6) bond length is 1.51 Å. The C(3)-O(3) bond length is 1.28 Å. The C(3)-O(7) bond length is 1.22 Å. In the twelfth C site, C(4) is bonded in a trigonal planar geometry to one C(1), one C(7), and one C(8) atom. The C(4)-C(7) bond length is 1.39 Å. The C(4)-C(8) bond length is 1.37 Å. In the thirteenth C site, C(5) is bonded in a trigonal planar geometry to one C(10), one C(2), and one C(9) atom. The C(5)-C(10) bond length is 1.41 Å. The C(5)-C(9) bond length is 1.39 Å. In the fourteenth C site, C(6) is bonded in a trigonal planar geometry to one C(11), one C(12), and one C(3) atom. The C(6)-C(11) bond length is 1.40 Å. The C(6)-C(12) bond length is 1.39 Å. In the fifteenth C site, C(7) is bonded in a distorted single-bond geometry to one C(13), one C(4), and one H(1) atom. The C(7)-C(13) bond length is 1.40 Å. The C(7)-H(1) bond length is 0.95 Å. In the sixteenth C site, C(8) is bonded in a distorted single-bond geometry to one C(4) and one H(2) atom. The C(8)-H(2) bond length is 0.95 Å. In the seventeenth C site, C(9) is bonded in a trigonal planar geometry to one C(11), one C(15), and one C(5) atom. The C(9)-C(11) bond length is 1.50 Å. The C(9)-C(15) bond length is 1.39 Å. In the eighteenth C site, C(10) is bonded in a distorted single-bond geometry to one C(16), one C(5), and one H(3) atom. The C(10)-C(16) bond length is 1.39 Å. The C(10)-H(3) bond length is 0.95 Å. In the nineteenth C site, C(11) is bonded in a trigonal planar geometry to one C(17), one C(6), and one C(9) atom. In the twentieth C site, C(12) is bonded in a distorted single-bond geometry to one C(18), one C(6), and one H(4) atom. The C(12)-H(4) bond length is 0.95 Å. In the twenty-first C site, C(13) is bonded in a trigonal planar geometry to one C(19), one C(20), and one C(7) atom. In the twenty-second C site, C(14) is bonded in a distorted single-bond geometry to one C(19) and one H(5) atom. The C(14)-H(5) bond length is 0.95 Å. In the twenty-third C site, C(15) is bonded in a distorted single-bond geometry to one C(21), one C(9), and one H(6) atom. The C(15)-H(6) bond length is 0.95 Å. In the twenty-fourth C site, C(16) is bonded in a trigonal planar geometry to one C(10), one C(21), and one C(22) atom. There are nine inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(7) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(8) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(10) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(12) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(14) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(15) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one C(17) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one C(21) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one C(23) atom. There are twelve inequivalent O sites. In the first O site, O(10) is bonded in a distorted L-shaped geometry to one Co(2) and one C(20) atom. In the second O site, O(11) is bonded in a bent 120 degrees geometry to one Co(2) and one C(22) atom. In the third O site, O(12) is bonded in a distorted single-bond geometry to one Na(3), one Co(2), and one C(20) atom. In the fourth O site, O(7) is bonded in a distorted single-bond geometry to one Na(1), one Na(2), and one C(3) atom. In the fifth O site, O(1) is bonded in a bent 120 degrees geometry to one Co(1) and one C(1) atom. In the sixth O site, O(2) is bonded in a bent 120 degrees geometry to one Co(1) and one C(2) atom. In the seventh O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Na(1) and one C(24) atom. In the eighth O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Co(1), and one C(3) atom. In the ninth O site, O(4) is bonded in a bent 120 degrees geometry to one Co(1) and one C(24) atom. In the tenth O site, O(5) is bonded in a single-bond geometry to one C(1) atom. In the eleventh O site, O(6) is bonded in a single-bond geometry to one C(2) atom. In the twelfth O site, O(9) is bonded in a single-bond geometry to one C(22) atom. Linkers: 48 [O]C(=O)c1ccc(-c2ccc(C([O])=O)cc2C([O])=O)c(C([O])=O)c1. Metal clusters: 4 O=[C]O[Co](O[C]=O)(O[C]=O)O[C]=O.O=[C]O[Co](O[C]O[Na])(O[C]=O)O[C]=O.O=[C]O[Co](O[C]O[Na])(O[C]=O)O[C]=O.O=[C]O[Co](O[C]O[Na])(O[C]=O)O[C]=O ,4 O=[C]O[Co](O[C]=O)(O[C]=O)O[C]=O.O=[C]O[Co](O[C]=O)(O[C]=O)O[C]=O.O=[C]O[Co](O[C]O[Na])(O[C]=O)O[C]=O.O=[C]O[Co](O[C]O[Na])(O[C]O[Na])O[C]=O ,8 O=[C]O[Co](O[C]=O)(O[C]=O)O[C]=O.O=[C]O[Co](O[C]O[Na])(O[C]=O)O[C]=O. The MOF has largest included sphere 4.87 A, density 1.36 g/cm3, surface area 3814.35 m2/g, accessible volume 0.26 cm3/g