Halogenated Benzene Cation Radicals
Halogenated Benzene Cation Radicals
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DOI：
10.1002/chem.201102960
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发表时间：
2012-05-01
影响因子：
4.3
通讯作者：
Seppelt, Konrad
中科院分区：
文献类型：
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作者：
Molski, Matthias J.;Mollenhauer, Doreen;Seppelt, Konrad
卤代苯C6 HF_5、2，4，6-C6 H_3F_3、2，3，5，6-C6 H_2F_4、C6 F_6、C6 Cl_6、C6 Br_6和C6 I_6在各种强氧化剂作用下转化为相应的阳离子自由基。阳离子自由基盐进行了分离，其特征在于通过电子顺磁共振（EPR）光谱和单晶X-射线衍射。阳离子自由基的热稳定性随着氢含量的降低而增加。正如预期的那样，阳离子自由基[C6 HF 5]+和2，3，5，6-[C6 H2 F4]+具有与C6 HF 5和2，3，5，6-[C6 H2 F4]相同的几何结构。相反，阳离子自由基[C6 F6]+，[C6 Cl 6]+，也可能[C6 Br 6]+在结晶状态下表现出JahnTeller扭曲的几何形状。在C6 F6 + Sb 2F 11-的情况下，在同一晶体中观察到两种低对称性几何构型。有趣的是，阳离子自由基2，4，6-[C6 H3 F3]+和C6 I6+的结构没有表现出JahnTeller畸变。密度泛函理论计算表明，对于2，4，6-[C6 H3 F3]+和[C6 I6]+，中性苯前体的D3 h或D 6 h对称性对这些阳离子没有畸变的解释是不同的。
The halogenated benzenes C6HF5, 2,4,6-C6H3F3, 2,3,5,6-C6H2F4, C6F6, C6Cl6, C6Br6, and C6I6 were converted into their corresponding cation radicals by using various strong oxidants. The cation-radical salts were isolated and characterized by electron paramagnetic resonance (EPR) spectroscopy and by single-crystal X-ray diffraction. The thermal stability of the cation radicals increased with decreasing hydrogen content. As expected, the cation radicals [C6HF5]+ and 2,3,5,6-[C6H2F4]+ had structures with the same geometry as C6HF5 and 2,3,5,6-[C6H2F4]. In contrast, the cation radicals [C6F6]+, [C6Cl6]+, and possibly also [C6Br6]+ exhibited JahnTeller-distorted geometries in the crystalline state. In the case of C6F6+Sb2F11-, two low-symmetry geometries were observed in the same crystal. Interestingly, the structures of the cation radicals 2,4,6-[C6H3F3]+ and C6I6+ did not exhibit JahnTeller distortions. DFT calculations showed that the explanation for the lack of distortion of these cations from the D3h or D6h symmetry of the neutral benzene precursor was different for 2,4,6-[C6H3F3]+ than for [C6I6]+.