The Influence of Redox-Innocent Donor Groups in Tetradentate Ligands Derived from o -Phenylenediamine: Electronic Structure Investigations with Nickel
The Influence of Redox-Innocent Donor Groups in Tetradentate Ligands Derived from o -Phenylenediamine: Electronic Structure Investigations with Nickel
复制标题
氧化还原无害供体基团对邻苯二胺衍生的四齿配体的影响：镍的电子结构研究
DOI：
10.1021/acs.inorgchem.9b01675
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发表时间：
2019
影响因子：
4.6
通讯作者：
Bart, Suzanne C.
中科院分区：
文献类型：
--
作者：
Spielvogel, Kyle D.;Coughlin, Ezra J.;Petras, Hayley;Luna, Javier A.;Benson, Austin;Donahue, Courtney M.;Kibasa, Amani;Lee, Kyounghoon;Salacinski, Ryan;Bart, Suzanne C.
氧化还原活性配体的持续发展需要了解配体修饰和相关因素如何影响金属络合物中氧化还原活性和自旋密度的位点。本文描述了含三芳基NNNN（1）和SNNS（2）配体的镍配合物的合成、表征和电子结构。研究了1和2中的四齿配体，并与具有组成相似配体的金属配合物中的配体进行了比较，以确定当氧化还原活性侧翼基团被氧化还原无辜的NMe 2或SMe取代时，以配体为中心的氧化还原性质如何变化。此外，我们还制备了一种2的衍生物，其中亚苯基主链被乙烯取代（3），以探讨邻苯二胺对配体中心氧化还原活性的重要性。循环伏安图收集1和2揭示了两个完全可逆的配体为中心的氧化还原事件。值得注意的是，几个准可逆的配体为中心的氧化还原波也观察到3，尽管没有邻苯二胺亚基。氧化1和2与银盐含有不同的抗衡阴离子（BF 4-，OTf-，NTf 2-）允许电化学生成的配合物进行分析，作为不同的氧化态的函数，使用单晶X射线衍射（XRD），EPR光谱，和S K边X射线吸收光谱。实验数据证实了DFT计算，并一起，他们揭示了如何在单和双氧化盐1和2的未成对的自旋密度和电子结构的位置变化取决于抗衡阴离子和外源配体，如吡啶的配位能力。
The continued development of redox-active ligands requires an understanding as to how ligand modifications and related factors affect the locus of redox activity and spin density in metal complexes. Here we describe the synthesis, characterization, and electronic structure of nickel complexes containing triaryl NNNN (1) and SNNS (2) ligands derived fromo-phenylenediamine. The tetradentate ligands in1and2were investigated and compared to those in metal complexes with compositionally similar ligands to determine how ligand-centered redox properties change when redox-active flanking groups are replaced with redox-innocent NMe2or SMe. A derivative of2in which the phenylene backbone was replaced with ethylene (3) was also prepared to interrogate the importance ofo-phenylenediamine for ligand-centered redox activity. Cyclic voltammograms collected for1and2revealed two fully reversible ligand-centered redox events. Remarkably, several quasi-reversible ligand-centered redox waves were also observed for3despite the absence of theo-phenylenediamine subunit. Oxidizing1and2with silver salts containing different counteranions (BF4–, OTf–, NTf2–) allowed the electrochemically generated complexes to be analyzed as a function of different oxidation states using single-crystal X-ray diffraction (XRD), EPR spectroscopy, and S K-edge X-ray absorption spectroscopy. The experimental data are corroborated by DFT calculations, and together, they reveal how the location of unpaired spin density and electronic structure in singly and doubly oxidized salts of1and2varies depending on the coordinating ability of the counteranions and exogenous ligands such as pyridine.