A bowl-shaped ortho-semiquinone radical anion: quantitative evaluation of the dynamic behavior of structural and electronic features.
A bowl-shaped ortho-semiquinone radical anion: quantitative evaluation of the dynamic behavior of structural and electronic features.
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DOI：
10.1002/anie.201002626
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发表时间：
2010-08
影响因子：
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通讯作者：
A. Ueda;K. Ogasawara;Shinsuke Nishida;T. Ise;Tomohiro Yoshino;S. Nakazawa;Kazunobu Sato;T. Takui;K. Nakasuji;Y. Morita
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文献类型：
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作者：
A. Ueda;K. Ogasawara;Shinsuke Nishida;T. Ise;Tomohiro Yoshino;S. Nakazawa;Kazunobu Sato;T. Takui;K. Nakasuji;Y. Morita
有机自由基离子在从生物化学到材料科学的广泛研究领域中发挥着越来越重要的作用。邻半醌是一种具有多级氧化还原能力的典型有机阴离子自由基，能与多种金属离子形成螯合盐和络合物。研究邻半醌自由基的过渡金属配合物不仅有助于提高人们对其基础化学的认识，而且有助于开发基于价态互变异构现象的功能材料。3]相比之下，碱金属盐已经被广泛研究，并且许多注意力集中在它们的结构和溶液中离子对的电子特征的动态行为上。5]一些碱金属盐的溶液相ESR谱测量显示其超精细耦合常数（hfccs）显着的温度依赖性。这种行为的起源已被定性解释为温度依赖性的位置变化或迁移的碱金属阳离子的氧原子的邻-半醌自由基。这种动态行为的定量讨论至今尚未进行。最近，我们合成并分离了稳定的基于corannulene（1）的具有碗状非交替p-共轭体系的中性单自由基和双自由基衍生物。从几何和拓扑两方面对它们的三维自旋离域性质和分子内、分子间的磁相互作用进行了实验研究。这些研究启发我们设计了一种新型的基于corannulene的碗状自由基阴离子体系2C，
Organic radical ions play increasingly important roles in a wide range of research fields from biochemistry to materials science. o-Semiquinone is a typical organic radical anion with multistage redox ability that can form chelate salts and complexes with many kinds of metal cations. Investigation of a variety of transition-metal complexes of o-semiquinone radical could help not only to increase general knowledge of their fundamental chemistry but also to develop functional materials based on valence tautomerism phenomena. 3] In contrast, the alkali-metal salts have been extensively studied, and much attention has been focused on the dynamic behavior of their structure and of the electronic features of the ion pair in solution. 5] Solution-phase ESR spectroscopy measurements of some alkali-metal salts show significant temperature dependence in their hyperfine coupling constants (hfccs). The origin of this behavior has been only qualitatively interpreted as temperature-dependent positional change or migration of the alkali-metal cation to the oxygen atoms of the o-semiquinone radical. A quantitative discussion of such dynamic behavior has not been carried out to date. Recently, we synthesized and isolated corannulene (1)based stable neutral monoand diradical derivatives with bowl-shaped non-alternant p-conjugated systems. Their three-dimensional spin-delocalized nature and intraand intermolecular magnetic interactions were experimentally illustrated in terms of geometrical and topological aspects. These studies have inspired us to design a novel bowl-shaped radical anion system 2C based on corannulene with the o-