Interdependent Metal-Metal Bonding and Ligand Redox-Activity in a Series of Dinuclear Macrocyclic Complexes of Iron, Cobalt, and Nickel.
Interdependent Metal-Metal Bonding and Ligand Redox-Activity in a Series of Dinuclear Macrocyclic Complexes of Iron, Cobalt, and Nickel.
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铁、钴和镍的一系列双核大环配合物中相互依赖的金属-金属键合和配体氧化还原活性。
DOI：
10.1021/acs.inorgchem.9b02339
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发表时间：
2020
影响因子：
4.6
通讯作者：
Tomson,NeilC
中科院分区：
文献类型：
--
作者：
Wang,Qiuran;Zhang,Shaoguang;Cui,Peng;Weberg,AlexanderB;Thierer,LauraM;Manor,BrianC;Gau,MichaelR;Carroll,PatrickJ;Tomson,NeilC
这份报告描述了一系列由氧化还原活性大环配体结合的双核铁、钴和镍配合物的等结构系列。该系列跨越五个氧化还原水平(34-38e-/簇核)，允许详细研究金属-金属相互作用的程度和基于配体的氧化还原活性的程度。采用磁学、电化学、UV-VIS-NIR吸收光谱和结晶学等手段，结合密度泛函理论计算分析，提取了六个同双核配合物的电子结构。等电子的34个e物种[(3PdI2)Fe2(PMe3)2(μ-Cl)](OTf)和[(3PdI2)Co2(PMe3)2(μ-Cl)](OTf)3表现为金属-金属单键，随着金属离子的有效核电荷，不同数量的电子密度离域到配体中。[(3PdI_2)CO_2(PMe_3)_2(μ-Cl)](OTf)_3的单电子和双电子还原导致了可分离的产物，表现为Co-Co距离和配体流形的还原程度的连续增加。这一趋势是由于Co-Coσ*轨道的还原所致，该轨道被发现与3PDI2配体的氧化还原活性流形严重混合。在37和38e-镍配合物[(3PdI2)Ni2(PMe3)2(μ-Cl)](OTf)2和[(3PdI2)Ni2(PMe3)2(μ-Cl)](OTf)中也观察到了类似的趋势；然而，它们较高的电子计数导致了高自旋基态，这是由于占据了具有显著Ni-NPDIδ/δ*特征的高位σ*流形。基态构型的这种变化改变了37e-络合物中的M-M键相互作用，但38个e-物种的形成再次破坏了M-M键，同时电子密度也转移到配体。
This report describes an isostructural series of dinuclear iron, cobalt, and nickel complexes bound by a redox-active macrocyclic ligand. The series spans five redox levels (34–38 e–/cluster core), allowing for a detailed investigation into both the degree of metal–metal interaction and the extent of ligand-based redox-activity. Magnetometry, electrochemistry, UV–vis–NIR absorption spectroscopy, and crystallography were used in conjunction with DFT computational analyses to extract the electronic structures of the six homodinuclear complexes. The isoelectronic, 34 e–species [(3PDI2)Fe2(PMe3)2(μ-Cl)](OTf) and [(3PDI2)Co2(PMe3)2(μ-Cl)](OTf)3exhibit metal–metal single bonds, with varying amounts of electron density delocalization into the ligand as a function of the effective nuclear charge of the metal ions. One- and two-electron reductions of [(3PDI2)Co2(PMe3)2(μ-Cl)](OTf)3lead to isolable products, which show successive increases in both the Co–Co distances and the extent of reduction of the ligand manifold. This trend results from reduction of a Co–Co σ* orbital, which was found to be heavily mixed with the redox-active manifold of the3PDI2ligand. A similar trend was observed in the 37 and 38 e–dinickel complexes [(3PDI2)Ni2(PMe3)2(μ-Cl)](OTf)2and [(3PDI2)Ni2(PMe3)2(μ-Cl)](OTf); however, their higher electron counts lead to high-spin ground states that result from occupation of a high-lying δ/δ* manifold with significant Ni–NPDIσ* character. This change in ground state configuration reforms a M–M bonding interaction in the 37 e–complex, but formation of the 38 e–species again disrupts the M–M bond alongside the transfer of electron density to the ligand.