Three-Step Spin Crossover in a Pseudo-3D Hofmann-Type Complex Originating from Anisotropic Supramolecular Interactions #MMPMID41337639
Li X; Belmouri NE; Sy M; Wolff M; Rotaru A; van Terwingen S; Maskowicz D; Sawczak M; Jendrzejewski R; Boukheddaden K; Garcia Y
J Am Chem Soc 2025[Dec]; ? (?): ? PMID41337639show ga
The development of multistep spin crossover materials is of considerable interest for molecular information processing and sensing applications and remains synthetically and mechanistically challenging. Herein, we present the first iron(II) two-dimensional Hofmann structure containing 1,2,4-triazole derivatives and [Au(CN)(2)](-) units, namely, Fe(MeOPhtrz)(2)[Au(CN)(2)](2) (1, MeOPhtrz = (E)-1-(2-methoxyphenyl)-N-(4H-1,2,4-triazol-4-yl)methanimine). The complex exhibits a temperature-induced three-step spin crossover behavior, confirmed by magnetic susceptibility, differential scanning calorimetry, Raman spectroscopy, single-crystal X-ray diffraction (SXRD), and optical microscopy. SXRD reveals a pseudothree-dimensional structure assembled through multiple intermolecular interactions, including hydrogen bonding, pi-pi stacking, and pi-Au interactions. These interactions contribute to an anisotropic supramolecular framework that induces a multistep spin crossover process. The sequential spin transition is likely driven by the differential rigidity along the crystallographic axes and the varied response of Fe-N bond lengths, leading to distinct transition steps. This study highlights the significance of supramolecular interactions in governing spin crossover properties and opens new avenues for the design of 2D Hofmann-like materials with tunable functionalities.
J+Am+Chem+Soc 2025 ; ? (?): ?
