FeC5H5O4 crystallizes in the trigonal R-3 space group. Fe(1) is bonded to one H(2), one O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted edge-sharing FeHO5 octahedra. The Fe(1)-H(2) bond length is 1.57 Å. The Fe(1)-O(1) bond length is 2.08 Å. There is one shorter (2.07 Å) and one longer (2.33 Å) Fe(1)-O(2) bond length. There is one shorter (1.93 Å) and one longer (2.07 Å) Fe(1)-O(3) bond length. There are five 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 1.41 Å. The C(1)-O(1) bond length is 1.27 Å. The C(1)-O(2) bond length is 1.26 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(4) atom. The C(2)-C(3) bond length is 1.41 Å. The C(2)-C(4) bond length is 1.45 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(2), one C(4), and one O(3) atom. The C(3)-C(4) bond length is 1.40 Å. The C(3)-O(3) bond length is 1.39 Å. In the fourth C site, C(4) is bonded in a distorted trigonal planar geometry to one C(2), one C(3), and one H(1) atom. The C(4)-H(1) bond length is 0.97 Å. In the fifth C site, C(5) is bonded in a tetrahedral geometry to one H(3), one H(4), one H(5), and one O(4) atom. The C(5)-H(3) bond length is 1.03 Å. The C(5)-H(4) bond length is 1.05 Å. The C(5)-H(5) bond length is 1.05 Å. The C(5)-O(4) bond length is 1.38 Å. There are five inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(4) atom. In the second H site, H(2) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one O(4) atom. The H(2)-O(4) bond length is 0.96 Å. In the third H site, H(3) is bonded in a single-bond geometry to one C(5) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(5) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(5) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees 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 two equivalent Fe(1) and one C(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Fe(1) and one C(3) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one C(5) and one H(2) atom. Linkers: 9 [O]C(=O)c1cc([O])c(C([O])=O)cc1[O]. Metal clusters: 18 [Fe]. The MOF has largest included sphere 7.74 A, density 1.38 g/cm3, surface area 3163.71 m2/g, accessible volume 0.39 cm3/g