Ossinger Sascha, Näther Christian, Buchholz Axel, Schmidtmann Marc, Mangelsen Sebastian, Beckhaus Rüdiger, Plass Winfried, Tuczek Felix
Institute of Inorganic Chemistry, Christian-Albrechts-University Kiel, Max-Eyth-Str.2, 24118 Kiel, Germany.
Institute of Inorganic and Analytical Chemistry, Friedrich-Schiller-University, 07743 Jena, Germany.
Inorg Chem. 2020 Jun 15;59(12):7966-7979. doi: 10.1021/acs.inorgchem.9b03354. Epub 2020 Feb 9.
Two polymorphic modifications ( and ) of the new spin crossover (SCO) complex [Fe{HB(pz)(pypz)}] (pz = pyrazole, pypz = pyridylpyrazole; ) were prepared and investigated by differential scanning calorimetry (DSC), magnetic measurements, Mößbauer, vibrational, and absorption spectroscopy as well as single-crystal and X-ray powder diffraction. DSC measurements reveal that upon heating the thermodynamically metastable form to ∼178 °C it transforms into in an exothermic reaction, which proves that these modifications are related by monotropism. Both forms show thermal SCO with values of 390 K () and 270 K (). An analysis of the crystal structures of and the corresponding Zn(II) () and Co(II) () complexes that are isotypic with reveals that form consists of dimers coupled by strong intramolecular π···π interactions, which is not the case for . In agreement with these findings, investigations of thin films of , where significant π···π interactions should be absent, reveal SCO behavior similar to that of . These results underscore the importance of cooperativity for the spin-transition behavior of this class of complexes.
制备了新型自旋交叉（SCO）配合物[Fe{HB(pz)(pypz)}]（pz = 吡唑，pypz = 吡啶基吡唑； ）的两种多晶型变体（ 和 ），并通过差示扫描量热法（DSC）、磁性测量、穆斯堡尔谱、振动光谱和吸收光谱以及单晶和X射线粉末衍射进行了研究。DSC测量表明，在将热力学亚稳形式 加热至约178 °C时，它会在放热反应中转变为 ，这证明这些变体通过单向性相关。两种形式均显示热自旋交叉， 值分别为390 K（ ）和270 K（ ）。对 以及与 同型的相应Zn(II)（ ）和Co(II)（ ）配合物的晶体结构分析表明， 形式由通过强分子内π···π相互作用耦合的二聚体组成，而 并非如此。与这些发现一致，对 薄膜的研究表明，其中应不存在明显的π···π相互作用，其显示出与 类似的自旋交叉行为。这些结果强调了协同作用对这类配合物自旋转变行为的重要性。
