CNRS, CRPP, UPR 8641 , F-33600 Pessac, France.
Univ. Bordeaux, CRPP, UPR 8641 , F-33600 Pessac, France.
J Am Chem Soc. 2018 Jan 10;140(1):98-101. doi: 10.1021/jacs.7b11042. Epub 2017 Dec 19.
An iron(II) pyridyl-benzohydrazonate-based complex decorated with long alkyl chains is reported as a rare spin-crossover compound displaying a wide thermal hysteresis spanning room temperature. On heating, this compound exhibits a spin transition between a LS ground state and an ordered HS-LS phase with symmetry breaking from monoclinic P2/n into orthorhombic P222 space groups. During cooling, the compound first transits into a magnetically distinguishable HS-LS phase with monoclinic P2 symmetry before returning into the LS phase. Interconversion between the two distinct HS-LS phases is the result of subtle structural changes in the alkyl chains and produces a second minor thermal hysteresis that superposes to the large one. This unprecedented result shows that the combination of a conventional cooperative spin transition and ligand-driven magnetic changes can promote magnetic tristability at room temperature.
报道了一种基于铁(II)吡啶苯甲酰腙的配合物，其表面修饰有长链烷基。这种配合物是一种罕见的自旋交叉化合物，具有跨越室温的宽热滞现象。在加热过程中，该化合物经历了从低自旋基态到有序高自旋-低自旋相的自旋转变，伴随着从单斜 P2/n 空间群到正交 P222 空间群的对称性破缺。在冷却过程中，该化合物首先经过一个具有单斜 P2 对称性的磁区分的高自旋-低自旋相，然后再回到低自旋相。两个不同的高自旋-低自旋相之间的相互转换是烷基链细微结构变化的结果，并产生了第二个较小的热滞，与较大的热滞相叠加。这一前所未有的结果表明，传统的协同自旋转变和配体驱动的磁变化的结合可以促进室温下的磁三重稳定性。
