Wu Yang, Liu Zeyu, Lu Tian, Orozco-Ic Mesías, Xu Jingbo, Yan Xiufen, Wang Jiaojiao, Wang Xia
School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, China.
Beijing Kein Research Center for Natural Sciences, Beijing 100022, China.
Inorg Chem. 2023 Dec 11;62(49):19986-19996. doi: 10.1021/acs.inorgchem.3c02675. Epub 2023 Nov 21.
The cyclo[18]carbon (C) has piqued widespread interest in recent years for its geometrical aesthetic and unique electronic structure. Inspired by it, theoretical investigations of its isoelectronic BN have been published occasionally; however, few studies considered their other companion BCN. In this work, we study the geometric structure, charge distribution, bonding characteristic, aromaticity, and electron delocalization of BCN and BN for the first time and compare the relevant results with those of C. Based on the comprehensive analysis of aromaticity indicators such as AV1245, nucleus-independent chemical shifts, anisotropy of the induced current density, magnetically induced current density, iso-chemical shielding surface, and induced magnetic field (), we found that BCN has definitely a double aromatic character similar to C and the aromaticities of the two are very close, while BN is a nonaromatic species. In response to this novel finding, we delved into its nature from an electron delocalization perspective through a localized orbital locator, electron localization function, Fermi hole, and atomic remote delocalization index analyses. The C atom between B and N as an interconnecting bridge strengthens the electron delocalization of the conjugate path, which is the essence of the significant enhancement of the molecular aromaticity from BN to BCN. This work elucidates that within the framework of the isoelectronicity of C, different methods of atomic doping can achieve molecules with completely different properties.
近年来，环[18]碳（C）因其几何美感和独特的电子结构引起了广泛关注。受其启发，关于其等电子体氮化硼（BN）的理论研究偶尔会有发表；然而，很少有研究考虑其另一个同系物硼碳氮（BCN）。在这项工作中，我们首次研究了BCN和BN的几何结构、电荷分布、键合特性、芳香性和电子离域，并将相关结果与C的结果进行比较。基于对诸如AV1245、核独立化学位移、感应电流密度各向异性、磁诱导电流密度、等化学屏蔽表面和感应磁场等芳香性指标的综合分析，我们发现BCN肯定具有与C相似的双重芳香特征，且二者的芳香性非常接近，而BN是一种非芳香性物种。针对这一新颖发现，我们通过定域轨道定位符、电子定域函数、费米空穴和原子远程离域指数分析，从电子离域角度深入探究了其本质。B和N之间的C原子作为连接桥增强了共轭路径的电子离域，这是分子芳香性从BN到BCN显著增强的本质。这项工作阐明了在C等电子体的框架内，不同的原子掺杂方法可以实现具有完全不同性质的分子。
