One goal that many scientists pursue is the unification of several interesting chemical or physical properties in one system, as only multifunctional materials will meet the challenges of today's technologies. With this background, three novel iron(II) coordination compounds with a Schiff base-like N₂O₂ coordinating ligand L bearing a sulfur-rich backbone are investigated in this work. Two of the complexes, the mononuclear [FeL(py)₂] (py = pyridine) and the coordination polymer {[FeL(bpee)]}_n [bpee = trans-1,2-bis(4-pyridyl)ethene], show spin crossover behavior followed using magnetic susceptibility measurements and Mössbauer spectroscopy. To get a closer insight into different states of the complex spin crossover behavior of {[FeL(bpee)]}_n, XPS measurements were conducted at different temperatures. Furthermore, impedance spectroscopic measurements at variable temperatures were performed to get insight into the electrical conductivity of this system. All iron(II) complexes were electrochemically characterized using cyclovoltammetric measurements, supplemented by DFT computation. Apparently, the extension by a sulfur backbone leads to a stabilization of the HOMO. Due to this, the complexes are more difficult to oxidize than comparable systems. With {[FeL(azpy)]}_n, another coordination polymer, this time axially decorated by the redox-active ligand azpy (azpy = 4,4′-azopyridine), is investigated, which is, however, a pure high spin complex.

中文翻译：

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具有富硫配体主链的铁（II）自旋交联络合物

许多科学家追求的目标是在一个系统中统一几个有趣的化学或物理特性，因为只有多功能材料才能满足当今技术的挑战。在此背景下，这项工作研究了三种具有席夫碱样N ₂ O ₂配体L的新型铁（II）配位化合物，该配体L带有富硫主链。两种配合物，单核[FeL（py）₂ ]（py =吡啶）和配位聚合物{[FeL（bpee）]} _n [bpee = 反式-1,2-双（4-吡啶基）乙烯]，使用磁化率测量和穆斯堡尔光谱法显示自旋交叉行为。为了更深入地了解{[FeL（bpee）]} _n的复杂自旋交叉行为的不同状态，在不同温度下进行了XPS测量。此外，在可变温度下进行了阻抗光谱测量，以深入了解该系统的电导率。所有的铁（II）配合物都通过电化学伏安法进行电化学表征，并辅以DFT计算。显然，硫主链的延伸导致HOMO的稳定。因此，与可比的体系相比，络合物更难以氧化。随着{[FeL（azpy）]} _n，研究了另一种配位聚合物，这次由氧化还原活性配体azpy（azpy = 4,4'-azopyridine）轴向修饰，但是，它是一种纯的高自旋络合物。