A new mixed-valent iron MOF, formulated 3 as Fe3O(F4BDC)(3)(H2O)(3).(DMF)(3.5) (1), has been synthesized by using a perfluorinated linear dicarboxylate to link trigonal prismatic Fe-3(mu(3)-O) (O2C-)(6) clusters. The structure refinement based on single crystal X-ray diffraction data collected from 1 reveals the material exhibits the acs topology with large channels along the crystallographic c-axis. Due to the presence of fluorine atoms the organic link, 2,3,5,6-tetrafluorobenzene-1,4-dicarboxylate (F4BDC), has a 63 degrees torsion angle between the carboxylate and aromatic planes, resulting in larger channels compared to those in the isoreticular material MOF-235. While few iron-based MOFs have demonstrated porosity, nitrogen and hydrogen sorption experiments carried out at 77 K proved the porosity of outgassed 1, which has a Langmuir surface are of 635 m(2)/g and a gravimetric capacity of 0.9 wt% of hydrogen at I bar. (c) 2006 Elsevier B.V. All rights reserved.