An alternative strategy to construct Fe(ii)-based MOFs with multifarious structures and magnetic behaviors

Abstract

An alternative strategy using cyclopentadienyliron dicarbonyl dimer as a starting material has been applied to construct six new Fe(II)-based MOFs, formulated as [Fe₂(Nic)₄(μ-H₂O)]·CH₃CN (1), [Fe(PIP)(H₂O)]·H₂O (2), [Fe(Hbidc)(H₂O)] (3), [Fe(Hbidc)] (4), [Fe(Py-3,4-BDC)(H₂O)₂]·H₂O (5) and [Fe(Py-3,4-BDC)(H₂O)₂] (6) (HNic = nicotinic acid, H₂PIP = 5-(pyridin-4-yl) isophthalic acid, H₃bidc = benzimidazole-5,6-dicarboxylic acid and Py-3,4-H₂BDC = 3,4-pyridinedicarboxylic acid). X-ray structural analysis reveals that 1 possesses a 3D framework, while the rest of the compounds are 2D layer structures which are further connected by hydrogen bonding into 3D supramolecular architectures. Magnetic analyses have been performed with the classical spin approximation, revealing that 2, 5 and 6 exhibit ferromagnetic interactions between Fe(II) ions, while 3 and 4 show antiferromagnetic interactions between Fe(II) centres. The successful preparation of compounds 1–6 may provide an alternative and useful approach for the synthesis of Fe(II)-based MOFs in the future.