学术讲座
报告题目:Large resonance energy in monocyclic molecules does not necessarily imply aromaticity
报告时间:2023-11-16 10:00
报告人: Slavko Radenković 副教授
University of Kragujevac
报告地点:卢嘉锡202报告厅
报告摘要:
The concept of aromaticity is a commonly employed tool to explain reactivity and stability of molecules. Resonance energy is closely related to the aromaticity phenomenon, and it is widely used as one of the criteria to measure aromaticity. There are many theoretical and experimental approaches which can be used to assess the extent of resonance energies in polycyclic conjugated compounds. The classical Valence Bond (VB) methods provide a straightforward way to compute the resonance energies. Here, we present a VB analysis of the electronic structure of Ge3(NH)3 which models experimentally characterized germanazene. In addition, we explored the aromatic character of germanazene and its analogues (E3(NH)3, E = C, Si, Sn, Pb) by means of the magnetically induced current density (MICD) and multicenter delocalization index (MCI). π-electronic systems of the studied germanazene Ge3(NH)3 and its analogues are isoelectronic with that of benzene, which is known to have an intensive cyclic π-delocalization. We found that Ge3(NH)3 is dominated by a nonbonded structure, wherein π-lone pairs are localized on the N atoms. Nevertheless, this molecule enjoys large covalent-ionic resonance energies of 86.6 kcal/mol, which reveals a strong stabilization by charge-shift bonding. Thus, unlike in benzene, in Ge3(NH)3 delocalization of π-electron pairs of the N atoms is primarily confined to the domains of their adjacent Ge atoms. Therefore, the present study shows that germanazene and its analogs are stabilized by large charge-shift resonance energies (RECS), rather than by the cyclic electron delocalization, as in the benzene archetype.
报告人简介:
Slavko Radenković于2012年前往法国巴黎六大进行博士后研究工作,合作导师Benoît Braïda。Radenković副教授的研究兴趣主要集中于分子的芳香性、分子的电子性质与反应活性的理论计算研究、新的化学键概念等,Radenković副教授熟悉金属成键的特性以及价键理论在金属键理论计算中的应用,发表科研论文数篇。
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