Synthesis, Characterization, and Properties of an Open-Framework Iron(III) Dicarboxylate: MIL-85 or FeIII2O{O2C-CH3}2{O2C-C6H4-CO2}·2CH3OH

A new three-dimensional iron(III) dicarboxylate, MIL85 or FeIII2O{O2C-CH3}2{O2C-C6H4-CO2}·2CH3OH, has been obtained under solvothermal conditions, and its structure was determined using X-ray powder diffraction data. Its chiral framework is built up from helical chains of iron(III) octahedra linked through terephthalate dianions. This creates a threedimensional structure with an array of 1-D small-pore channels filled with free and bound methanol moieties. The thermal behavior has been investigated using TGA, and X-ray thermodiffractometry indicates that MIL-85 is stable up to 275 C with a fully reversible departure of solvent process. When the free and bound solvent molecules are removed, a nanoporous solid with a Langmuir surface area of 110 m2/g is obtained. Mossbauer spectrometry confirms the presence of highspin-state Fe3+ within the structure and a change in the iron environment upon solvent departure. Finally, one can conclude from magnetic data that MIL-85 exhibits a frustrated magnetic behavior in the lowtemperature range. Crystal data for MIL-85: hexagonal space group P61 (n. 169) with a = 11.045 (1) A, c = 18.823 (1) A, and Z = 6.