Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel.
Faculty of Science, University of Kragujevac, 12 Radoja Domanovica, 34000, Kragujevac, Serbia.
Chemistry. 2023 Jun 27;29(36):e202300992. doi: 10.1002/chem.202300992. Epub 2023 May 5.
We present here a valence bond analysis of structure and π-delocalization in Ge (NH) , which models germanazene that was prepared by Power et al. To get a broader perspective, we explore the entire E (NH) series (E=C, Si, Ge, Sn, Pb). Thus, while (4n+2)π systems of carbon rings are aromatic with cyclic π-delocalization, the E (NH) rings are dominated by a nonbonded structure, wherein π-lone pairs are localized on the N atoms. Nevertheless, these molecules enjoy large covalent-ionic resonance energies of 153.0, 86.6, 74.2, 61.2, and 58.9 kcal/mol, respectively, for E=C, Si, Ge, Sn, Pb. The covalent-ionic mixing in E (NH) creates π-systems, which are stabilized by charge-shift bonding. Thus, unlike in benzene, in Ge (NH) delocalization of π-electron pairs of the N atoms is primarily confined to the domains of their adjacent Ge atoms. These features carry over to the substituted germanazene, Ge (NAr) (Ar=Ph).
我们在此提出了 Ge(NH) 的价键分析，用于模拟 Power 等人制备的锗氮烯。为了获得更广泛的视角，我们研究了整个 E(NH) 系列（E=C、Si、Ge、Sn、Pb）。因此，尽管具有(4n+2)π 环的碳环具有芳香性和环状π离域，但 E(NH) 环主要由非键结构主导，其中π孤对电子定域在 N 原子上。然而，这些分子分别具有 153.0、86.6、74.2、61.2 和 58.9 kcal/mol 的大共价-离子共振能，对于 E=C、Si、Ge、Sn 和 Pb。E(NH) 中的共价-离子混合形成了π系统，这些系统通过电荷转移键合得到稳定。因此，与苯不同，在 Ge(NH) 中，N 原子的π电子对的离域主要局限于其相邻 Ge 原子的区域。这些特征在取代的锗氮烯 Ge(NAr)（Ar=Ph）中也存在。
