Air‐Free Synthesis of a Ferrous Metal‐Organic Framework Featuring HKUST‐1 Structure and its Mössbauer Spectrum

Single crystals of the Fe II metal‐organic framework (MOF) with 1,3,5‐benzenetricarboxylate (BTC) as a linker were solvothermally obtained under air‐free conditions. X‐ray diffraction analysis of the crystals demonstrated a structure for Fe II ‐MOF analogous to that of [Cu 3 (BTC) 2 ] (HKUST‐1). Unlike HKUST‐1, however, the Fe II ‐MOF did not retain permanent porosity after exchange of guest molecules. The Mössbauer spectrum of the Fe II ‐MOF was recorded at 80 K in zero field yielding an apparent quadrupole splitting of ΔE Q = 2.43 mm · s –1 , and an isomer shift of δ = 1.20 mm · s –1 , consistent with high‐spin central iron(II) atoms. Air exposure of the Fe II ‐MOF was found to result in oxidation of the metal atoms to afford Fe III . These results demonstrate that Fe II ‐based MOFs can be prepared in similar fashion to the [Cu 3 (BTC) 2 ], but that they lack permanent porosity when degassed.