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Bis(pyrazolato) Bridged Diiron Complexes: Ferromagnetic Coupling in a Mixed‐Valent HS‐FeII/LS‐FeIII Dinuclear Complex
European Journal of Inorganic Chemistry ( IF 2.2 ) Pub Date : 2020-10-07 , DOI: 10.1002/ejic.202000697
Joanne W. L. Wong 1 , Shao‐An Hua 1 , Serhiy Demeshko 1 , Sebastian Dechert 1 , Shengfa Ye 2 , Franc Meyer 1
Affiliation  

Using a new bis(tridentate) compartmental pyrazolate‐centered ligand HL, the bis(pyrazolato)‐bridged diiron complex [L2FeII2][OTf]2 (1) and its singly oxidized mixed‐valent congener [L2FeIIFeIII][OTf]3 (2) have been synthesized and structurally characterized. While 1 features two HS‐FeII ions coordinated to two cis‐axial pyridine moieties in a highly distorted octahedral environment, the metal ions in 2 are coordinated by the ligand strand in a trans‐axial configuration. Very different Fe–N bond lengths and distinctly different coordination polyhedra are associated with pronounced valence localization in the case of 2. The electronic structures and magnetic properties of 1 and 2 have been further investigated by Mössbauer spectroscopy and variable temperature magnetic susceptibility measurements. In the case of 1, weak antiferromagnetic coupling is observed between the two HS‐FeII ions (J = –0.6 cm–1), while the HS‐FeII and LS‐FeIII ions in 2 are ferromagnetically coupled (J = +5.2 cm–1) to give an ST = 5/2 ground state with significant zero‐field splitting (DFe(II) = 2.3 cm–1). The findings are rationalized with the help of DFT computations.

中文翻译:

双(吡唑并酮)桥联的Diiron配合物:混合价HS-FeII / LS-FeIII双核配合物中的铁磁耦合

使用新的以双(三齿)间隔吡唑酸酯为中心的配体HL,双(吡唑并酮)桥接的二铁配合物[L 2 Fe II 2 ] [OTf] 21)及其单氧化混合价同类物[L 2 Fe II Fe III ] [OTf] 32)已合成并进行了结构表征。尽管1在高度扭曲的八面体环境中具有两个HS-Fe II离子与两个顺式吡啶基部分配位,但2中的金属离子由反式中的配体链配位轴向配置。在2的情况下,非常不同的Fe–N键长和明显不同的配位多面体与显着的化合价定位有关。Mössbauer光谱法和可变温度磁化率测量进一步研究了12的电子结构和磁性。在的情况下1,弱的反铁磁耦合,在两个HS-铁之间观察到II离子(Ĵ = -0.6厘米-1),而HS-的Fe II和LS-的Fe III中的离子2都铁磁耦合(Ĵ = + 5.2厘米–1)给出S T = 5/2的基态,并具有明显的零场分裂(D Fe(II) = 2.3 cm –1)。在DFT计算的帮助下,对发现进行了合理化。
更新日期:2020-11-16
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