Valadbeigi Younes
Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.
J Mol Graph Model. 2018 Mar;80:104-112. doi: 10.1016/j.jmgm.2017.12.026. Epub 2018 Jan 5.
Aromaticities and stabilities of ortho, meta, and para isomers of some derivatives of benzene, CH and CH were studied and compared basis on the NICS index and their relative energies. For the benzene and CH derivatives, the ortho isomers with less stability were more aromatic. This discrepancy was also observed for the molecules with conjugated and non-conjugated π-electrons. However, for the charged conjugated systems, the structures with delocalized charge were more stable. Effect of electron withdrawing (EWGs) and electron donating groups (EDGs) on the electron delocalization and stability of the neutral and charged molecules was investigated. It was observed that the EWDs and EDGs change the stability trend of the neutral systems, while in the case of charged molecules, the isomers with delocalized charge were more stable regardless of the type of substituents. Although both π-electron delocalization and charge delocalization stabilize the aromatic and conjugated systems, effect of charge delocalization on the stability is more than that of π-electron delocalization.
基于NICS指数及其相对能量，研究并比较了苯、CH和CH的一些衍生物的邻位、间位和对位异构体的芳香性和稳定性。对于苯和CH衍生物，稳定性较差的邻位异构体具有更高的芳香性。在具有共轭和非共轭π电子的分子中也观察到了这种差异。然而，对于带电共轭体系，电荷离域的结构更稳定。研究了吸电子基团（EWGs）和供电子基团（EDGs）对中性和带电分子的电子离域和稳定性的影响。观察到EWDs和EDGs改变了中性体系的稳定性趋势，而对于带电分子，无论取代基类型如何，电荷离域的异构体更稳定。虽然π电子离域和电荷离域都能使芳香和共轭体系稳定，但电荷离域对稳定性的影响大于π电子离域。
