FeH6(C3O)4 crystallizes in the monoclinic C2/c space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(5) atom. The Fe(1)-O(1) bond length is 2.21 Å. The Fe(1)-O(2) bond length is 2.27 Å. The Fe(1)-O(3) bond length is 2.10 Å. The Fe(1)-O(5) bond length is 2.06 Å. In the second Fe site, Fe(2) is bonded in an octahedral geometry to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms. Both Fe(2)-O(2) bond lengths are 2.20 Å. Both Fe(2)-O(4) bond lengths are 2.17 Å. Both Fe(2)-O(6) bond lengths are 2.17 Å. There are eighteen inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(2), one O(1), and one O(2) atom. The C(1)-C(2) bond length is 1.50 Å. The C(1)-O(1) bond length is 1.24 Å. The C(1)-O(2) bond length is 1.27 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one C(1), one C(3), and one C(6) atom. The C(2)-C(3) bond length is 1.41 Å. The C(2)-C(6) bond length is 1.36 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(2) and one H(1) atom. The C(3)-H(1) bond length is 0.93 Å. In the fourth C site, C(4) is bonded in a distorted single-bond geometry to one C(5) and one H(2) atom. The C(4)-C(5) bond length is 1.41 Å. The C(4)-H(2) bond length is 0.93 Å. In the fifth C site, C(5) is bonded in a trigonal planar geometry to one C(4), one C(5), and one C(6) atom. The C(5)-C(5) bond length is 1.42 Å. The C(5)-C(6) bond length is 1.41 Å. In the sixth C site, C(6) is bonded in a distorted single-bond geometry to one C(2), one C(5), and one H(3) atom. The C(6)-H(3) bond length is 0.93 Å. In the seventh C site, C(7) is bonded in a distorted bent 120 degrees geometry to one C(8), one O(3), and one O(4) atom. The C(7)-C(8) bond length is 1.51 Å. The C(7)-O(3) bond length is 1.26 Å. The C(7)-O(4) bond length is 1.25 Å. In the eighth C site, C(8) is bonded in a trigonal planar geometry to one C(11), one C(7), and one C(9) atom. The C(8)-C(11) bond length is 1.35 Å. The C(8)-C(9) bond length is 1.40 Å. In the ninth C site, C(9) is bonded in a distorted single-bond geometry to one C(8) and one H(4) atom. The C(9)-H(4) bond length is 0.93 Å. In the tenth C site, C(10) is bonded in a distorted single-bond geometry to one C(12) and one H(5) atom. The C(10)-C(12) bond length is 1.39 Å. The C(10)-H(5) bond length is 0.93 Å. In the eleventh C site, C(11) is bonded in a distorted single-bond geometry to one C(12), one C(8), and one H(6) atom. The C(11)-C(12) bond length is 1.44 Å. The C(11)-H(6) bond length is 0.93 Å. In the twelfth C site, C(12) is bonded in a trigonal planar geometry to one C(10), one C(11), and one C(12) atom. The C(12)-C(12) bond length is 1.41 Å. In the thirteenth C site, C(13) is bonded in a distorted bent 120 degrees geometry to one C(14), one O(5), and one O(6) atom. The C(13)-C(14) bond length is 1.50 Å. The C(13)-O(5) bond length is 1.25 Å. The C(13)-O(6) bond length is 1.25 Å. In the fourteenth C site, C(14) is bonded in a trigonal planar geometry to one C(13), one C(15), and one C(18) atom. The C(14)-C(15) bond length is 1.40 Å. The C(14)-C(18) bond length is 1.38 Å. In the fifteenth C site, C(15) is bonded in a distorted single-bond geometry to one C(14) and one H(7) atom. The C(15)-H(7) bond length is 0.93 Å. In the sixteenth C site, C(16) is bonded in a single-bond geometry to one C(17) and one H(8) atom. The C(16)-C(17) bond length is 1.42 Å. The C(16)-H(8) bond length is 0.93 Å. In the seventeenth C site, C(17) is bonded in a trigonal planar geometry to one C(16), one C(17), and one C(18) atom. The C(17)-C(17) bond length is 1.41 Å. The C(17)-C(18) bond length is 1.41 Å. In the eighteenth C site, C(18) is bonded in a distorted single-bond geometry to one C(14), one C(17), and one H(9) atom. The C(18)-H(9) bond length is 0.93 Å. There are nine inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(4) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(6) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(9) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(10) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(11) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one C(15) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one C(16) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one C(18) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted L-shaped geometry to one Fe(1) and one C(1) atom. In the second 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 third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one C(7) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one C(7) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Fe(1) and one C(13) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(2) and one C(13) atom. Linkers: 6 [O]C(=O)c1ccc2cc(C([O])=O)ccc2c1. Metal clusters: 2 [C]1O[Fe]2O[C]O[Fe]34(O1)(O[C]O2)O[C]O[Fe](O[C]O3)O[C]O4. RCSR code: pcu. The MOF has largest included sphere 5.64 A, density 1.07 g/cm3, surface area 4148.51 m2/g, accessible volume 0.52 cm3/g