Di-Iron(II) [2+2] Helicates of Bis-(Dipyrazolylpyridine) Ligands: The Influence of the Ligand Linker Group on Spin State Properties.
Di-Iron(II) [2+2] Helicates of Bis-(Dipyrazolylpyridine) Ligands: The Influence of the Ligand Linker Group on Spin State Properties.
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DOI：
10.1002/chem.202202578
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发表时间：
2023-02-10
影响因子：
4.3
通讯作者：
Halcrow, Malcolm A.
中科院分区：
文献类型：
--
作者：
Kulmaczewski, Rafal;Armstrong, Isaac T.;Catchpole, Pip;Ratcliffe, Emily S. J.;Vasili, Hari Babu;Warriner, Stuart L.;Cespedes, Oscar;Halcrow, Malcolm A.
合成了丁烷-1，4-二基(L 1)、吡啶-2，6-二基(L 2)、苯-1，2-二甲基(L 3)和丙烷-1，3-二基(L 4)四种bis[2‐{pyrazol‐1‐yl}‐6‐{pyrazol‐3‐yl}pyridine]配体。经适当的铁(II)前驱体处理后，L 1和L 2形成了[Fe2(μ−L)2]X4(X−=BF4−或ClO4−)螺旋配合物。[Fe2(μ−L 1)2][BF4]4的溶胶酸晶体具有三种不同的螺旋构象，其丁二基连接基的扭转率不同。溶剂化合物表现出逐渐的热自旋交叉，例如逐步切换和部分自旋交叉到低温混合自旋形式。[Fe2(μ−L 2)2]4+的盐是高自旋的，这反映了它们的高度扭曲的铁配位几何结构。用质谱仪和核磁共振氢谱研究了铁(II)与L 1−L 3形成的组装结构的组成和动力学。气相密度泛函理论计算表明，[Fe2(μ−L 1)2]4+中丁二基连接体的构象对其自旋态性质有影响，但由于铁原子间的分子内静电排斥作用而出现反常现象。这种二铁(II)络合物已经结晶成三种不同的螺旋构象，这三种构象在丁烷-1，4-二基配体连接基的扭转方面有所不同。晶体表现出一系列的自旋态性质，包括两个铁原子的逐步自旋交叉。具有刚性吡啶-2，6-二基间隔物的相关配体形成更扭曲的高自旋二铁(II)螺旋结构。
Four bis[2‐{pyrazol‐1‐yl}‐6‐{pyrazol‐3‐yl}pyridine] ligands have been synthesized, with butane‐1,4‐diyl (L 1), pyrid‐2,6‐diyl (L 2), benzene‐1,2‐dimethylenyl (L 3) and propane‐1,3‐diyl (L 4) linkers between the tridentate metal‐binding domains. L 1 and L 2 form [Fe2(μ−L)2]X4 (X−=BF4 − or ClO4 −) helicate complexes when treated with the appropriate iron(II) precursor. Solvate crystals of [Fe2(μ−L 1)2][BF4]4 exhibit three different helicate conformations, which differ in the torsions of their butanediyl linker groups. The solvates exhibit gradual thermal spin‐crossover, with examples of stepwise switching and partial spin‐crossover to a low‐temperature mixed‐spin form. Salts of [Fe2(μ−L 2)2]4+ are high‐spin, which reflects their highly twisted iron coordination geometry. The composition and dynamics of assembly structures formed by iron(II) with L 1−L 3 vary with the ligand linker group, by mass spectrometry and 1H NMR spectroscopy. Gas‐phase DFT calculations imply the butanediyl linker conformation in [Fe2(μ−L 1)2]4+ influences its spin state properties, but show anomalies attributed to intramolecular electrostatic repulsion between the iron atoms. This diiron(II) complex has been crystallized in three different helicate conformations, which differ in the torsions of the butane‐1,4‐diyl ligand linker groups. The crystals exhibit a range of spin state properties, including stepwise spin‐crossover of the two iron atoms. A related ligand with a rigid pyrid‐2,6‐diyl spacer forms more a distorted, high‐spin diiron(II) helicate structure.
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影响因子：
2.3
作者：
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通讯作者：
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4.9
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