Synthesis, Crystal Structure, Electrochemical Behavior, and Hirshfeld Surface Analysis of an Ionic Mixed‐valence Fe(II)–Fe(III) Complex

Abstract Herein, we report the synthesis and characterization of a new mixed‐valence ion‐pair Fe(II)‐Fe(III) complex, [Fe II (L) 3 ][(Fe III Cl 3 ) 2 (μ‐O)], consisting of an anionic dinuclear Fe(III) complex and a cationic mononuclear Fe(II) complex, where L = 2‐acetylpyridine hydrazone. The compound was characterized by spectroscopic methods, and its structure was unambiguously determined by single‐crystal X‐ray diffraction. The crystallographic analysis revealed that the complex crystallizes in the monoclinic space group P 2 1 / n . In the cation, the Fe(II) center is coordinated by three bidentate ligands, adopting a distorted octahedral geometry with a meridional arrangement. The anionic unit comprises two distorted tetrahedral Fe(III) centers bridged by an oxo ligand. The crystal structure is further stabilized by N─H···Cl hydrogen bonds, which interconnect the cations and anions into a three‐dimensional supramolecular network. Hirshfeld surface analyses were performed to investigate the nature and relative contribution of intermolecular interactions within the crystal lattice. In addition, the electrochemical behavior of the complex was examined, revealing characteristic redox processes.