A strongly hydrogen-bonded one-dimensional high-spin dinuclear Fe(II) complex.

In this study, we report the synthesis and detailed characterization of a novel chain compound, composed of hydrogen-bonded dinuclear complexes, in which two Fe(II) ions are bridged by a 2,2'-biimidazolate (bim2-) dianion. The crystal structure of [(tpma)Fe(μ-bim)Fe(Hbim)2] (1), where tpma = tris(2-pyridylmethyl)amine, exhibits a 1D zigzag chain architecture, formed through double hydrogen bonds between terminal 1H-2,2'-biimidazolate monoanions (Hbim-), with an N⋯H distance of 1.72 Å. Magnetic susceptibility measurements reveal weak antiferromagnetic coupling between the Fe(II) centers with the exchange constant J = -1.4 cm-1, mediated by the bridging ligand. The directional hydrogen bonding network, combined with π-π and H-π intermolecular interactions, suggests potential for proton dynamics that could lead to ferroelectric behavior. This complex represents the first example of a bim2- ligand bridging two iron ions and the first dimeric complex containing both bim2- and Hbim- ligands, which form strong one-dimensional hydrogen bonds. Investigation of ferroelectric behavior and potential interplay between functional properties are ongoing.