Li Qingzhong, Guo Xin, Yang Xin, Li Wenzuo, Cheng Jianbo, Li Hai-Bei
The Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Yantai University, Yantai 264005, People's Republic of China.
Phys Chem Chem Phys. 2014 Jun 21;16(23):11617-25. doi: 10.1039/c4cp01209g. Epub 2014 May 8.
A single-electron tetrel bond was predicted and characterized in FXH3···CH3 (X = C, Si, Ge, and Sn) complexes by performing quantum chemical calculations, where the methyl radical acts as the Lewis base and the σ-hole on the X atom in FXH3 as the Lewis acid. The interaction between the methyl radical and FXH3 is characterized by a red shift of F-X stretching frequency. The strength of the tetrel bond becomes stronger by not only increasing the atomic number of the central atom X (X = C, Si, Ge, and Sn) but also by enhancing the electron-withdrawing ability of substituents in the Lewis acid. The energy decomposition analysis highlights the importance of the electrostatic interaction in the formation of the tetrel bond, although the dispersion part is also non-negligible for the weak tetrel bond. There is a competition between the formation of single-electron tetrel bonds and hydrogen bonds for the complexes composed of the methyl radical and CNCH3 or NCCH3. Furthermore, the single-electron tetrel bond exhibits the cooperative effect not only with the hydrogen bond in the complex of NCH···NCCH3···CH3, but also with the conventional tetrel bond in NCCH3···NCCH3···CH3.
通过量子化学计算预测并表征了FXH3···CH3（X = C、Si、Ge和Sn）配合物中的单电子碳族元素键，其中甲基自由基作为路易斯碱，FXH3中X原子上的σ-空穴作为路易斯酸。甲基自由基与FXH3之间的相互作用通过F-X伸缩频率的红移来表征。不仅通过增加中心原子X（X = C、Si、Ge和Sn）的原子序数，而且通过增强路易斯酸中取代基的吸电子能力，碳族元素键的强度会变得更强。能量分解分析突出了静电相互作用在碳族元素键形成中的重要性，尽管对于弱碳族元素键，色散部分也不可忽略。对于由甲基自由基和CNCH3或NCCH3组成的配合物，单电子碳族元素键的形成与氢键之间存在竞争。此外，单电子碳族元素键不仅在NCH···NCCH3···CH3配合物中与氢键表现出协同效应，而且在NCCH3···NCCH3···CH3中与传统碳族元素键也表现出协同效应。
