National Medicines Institute, 00-725 Warsaw, Poland.
Institute of Nuclear Chemistry and Technology, 03-195 Warsaw, Poland.
Int J Mol Sci. 2021 Jun 28;22(13):6936. doi: 10.3390/ijms22136936.
In 30 monosubstituted benzene cation radicals, studied at the ωB97XD/aug-cc-pVTZ level, the phenyl rings usually adopt a compressed form, but a differently compressed form-equivalent to an elongated one-may coexist. The computational and literature ionization potentials are well correlated. The geometrical and magnetic aromaticity, estimated using HOMA and NICS indices, show the systems to be structurally aromatic but magnetically antiaromatic or only weakly aromatic. The partial charge is split between the substituent and ring and varies the most at C(ipso). In the ring, the spin is 70%, concentrated equally at the C(ipso) and C(p) atoms. The sEDA() and pEDA() descriptors of the substituent effect in cation radicals, respectively, were determined. In cation radicals, the substituent effect on the σ-electron system is like that in the ground state. The effect on the π-electron systems is long-range, and its propagation in the radical quinone-like ring is unlike that in the neutral molecules. The pEDA() descriptor correlates well with the partial spin at C(ipso) and C(p) and weakly with the HOMA() index. The correlation of the spin at the ring π-electron system and the pEDA() descriptor shows that the electron charge supplied to the ring π-electron system and the spin flow oppositely.
在 30 个单取代苯阳离子自由基中，在 ωB97XD/aug-cc-pVTZ 水平上进行了研究，芳环通常采用压缩形式，但也可能共存不同程度的压缩形式——等效于伸长形式。计算和文献电离势很好地相关。使用 HOMA 和 NICS 指数估算的几何和磁芳香性表明，这些系统在结构上是芳香的，但在磁学上是反芳香的或只有较弱的芳香性。部分电荷在取代基和环之间分配，在 C(ipso)处变化最大。在环中，自旋为 70%，均匀集中在 C(ipso)和 C(p)原子上。确定了阳离子自由基中取代基效应的 sEDA()和 pEDA()描述符。在阳离子自由基中，取代基对 σ 电子体系的影响与基态相同。对 π 电子体系的影响是远程的，其在自由基醌类似环中的传播与中性分子不同。pEDA()描述符与 C(ipso)和 C(p)处的部分自旋很好地相关，与 HOMA()指数弱相关。环中 π 电子体系的自旋与 pEDA()描述符的相关性表明，电子电荷被供应到环中 π 电子体系，而自旋流则相反。
