The simultaneous presence of different electrophores provides an interesting playground for responsive materials. Herein, we present the incorporation of a twice-reversibly oxidizable tetrathiafulvalene (TTF) unit into a binucleating ligand, bridging two metal centers in a fully conjugated plane. A two-step synthesis scheme gave the D_2h symmetric Schiff base-like ligand H₄L in moderate yields from which the corresponding copper(II) [Cu₂L], nickel(II) [Ni₂L], [Ni₂L(py)₄] and iron(II) complexes [Fe₂L(py)₄], [Fe₂L(dmap)₄] and [Fe₂L(bpee)₂]·1 Tol could be obtained. Characterization was performed through ¹H-NMR, IR, UV-vis and ⁵⁷Fe-Mössbauer spectroscopy, SQUID magnetometry and cyclic voltammetry, supported by density functional theory (DFT) calculations. Single crystal X-ray analysis of [Ni₂L(py)₄] revealed six-coordinate paramagnetic centers, whereas [Ni₂L] underwent gradual coordination induced spin state switching (CISSS) in solution. The magnetic independence of both metal centers is echoed by close-to-ideal Curie-plots of the [Cu₂L] system and the gradual spin crossover of all iron(II) compounds. By contrast, cyclic voltammetry measurements in solution indicated oxidation-dependent TTF–metal interactions, as well as metal–metal interactions. The reversible TTF-borne events in H₄L and [Ni₂L] are overlaid with metal-borne events in the case of [Fe₂L(py)₄], as is corroborated by an analysis of the frontier orbital landscapes and through diagnostic spectral features upon chemical oxidation.

中文翻译：

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双核 Jäger 型 {(N2O2)2}4− 配体：Fe(II)、Ni(II) 和 Cu(II) 穿过面内 TTF 桥的磁性和电子相互作用

不同电泳的同时存在为响应材料提供了一个有趣的游乐场。在此，我们提出将两次可逆氧化的四硫富瓦烯（TTF）单元合并到双核配体中，在完全共轭平面上桥接两个金属中心。两步合成方案以中等产率得到了 D _2h对称席夫碱配体 H ₄ L，其中相应的铜( II ) [Cu ₂ L]、镍( II ) [Ni ₂ L]、[Ni ₂ L可以得到[Fe ₂ L( py) ₄ ]和铁( II )络合物[Fe 2 L(py) ₄ ]、[Fe ₂ L(dmap) ₄ ]和[Fe ₂ L(bpee) ₂ ]·1 Tol 。通过¹ H-NMR、IR、UV-vis 和⁵⁷ Fe-Mössbauer 光谱、SQUID 磁力测定法和循环伏安法进行表征，并得到密度泛函理论 (DFT) 计算的支持。[Ni ₂ L(py) ₄ ]的单晶X射线分析揭示了六配位顺磁中心，而[Ni ₂ L]在溶液中经历了逐渐配位诱导的自旋态转换(CISSS)。[Cu ₂ L]系统的接近理想的居里图和所有铁 ( II ) 化合物的逐渐自旋交叉反映了两个金属中心的磁性独立性。相比之下，溶液中的循环伏安法测量表明存在氧化依赖性 TTF-金属相互作用，以及金属-金属相互作用。 H ₄ L和[Ni ₂ L]中的可逆 TTF 传播事件与[Fe ₂ L(py) ₄ ]中的金属传播事件重叠，这一点通过对前沿轨道景观的分析和通过化学氧化的诊断光谱特征。