Xu Huili, Cheng Jianbo, Yang Xin, Liu Zhenbo, Li Wenzuo, Li Qingzhong
Laboratory of Theoretical and Computational, Chemistry and School of Chemistry and Chemical Engineering, Yantai University, Yantai, 264005, China.
Chemphyschem. 2017 Sep 20;18(18):2442-2450. doi: 10.1002/cphc.201700660. Epub 2017 Aug 11.
The σ-hole tetrel bond in pyrazine/1,4-dicyanobenzene⋅⋅⋅TH F (T=C and Si) and the π-hole tetrel bond in pyrazine/1,4-dicyanobenzene⋅⋅⋅F TO have been compared. The π-hole tetrel bond is stronger than the corresponding σ-hole tetrel bond, with a larger interaction energy, shorter binding contact, greater electron density, and bigger charge transfer. Pyrazine forms a more stable tetrel-bonded complex than 1,4-dicyanobenzene even though the nitrogen atom in the former has a smaller negative electrostatic potential than the latter. An interesting cooperative effect was found when anion-π and tetrel-bond interactions coexisted in the same multicomponent complex of X ⋅⋅⋅pyrazine/1,4-dicyanobenzene⋅⋅⋅TH F/F TO (X=F, Cl, and Br). Both interactions displayed a positive cooperative effect, as shown by the larger interaction energies, shorter binding separations, and greater electron densities. The enhancement in the tetrel bond is dependent on the strength of the anion-π interaction and it becomes larger in the order Br <Cl <F . The enhancement in the tetrel bond changes its nature from a purely closed-shell interaction to a partially covalent interaction. Conversely, the anion-π interaction shows a prominent strengthening of up to -38 kcal mol . This effect has been analyzed in terms of electrostatic potentials and charge transfer.
已对吡嗪/1,4 - 二氰基苯···四氢呋喃（T = C和Si）中的σ - 空穴四元键和吡嗪/1,4 - 二氰基苯···氟氧化硫中的π - 空穴四元键进行了比较。π - 空穴四元键比相应的σ - 空穴四元键更强，具有更大的相互作用能、更短的键接触、更大的电子密度和更大的电荷转移。尽管吡嗪中的氮原子比1,4 - 二氰基苯中的氮原子具有更小的负静电势，但吡嗪形成的四元键配合物比1,4 - 二氰基苯更稳定。当阴离子 - π和四元键相互作用共存于X···吡嗪/1,4 - 二氰基苯···四氢呋喃/氟氧化硫（X = F、Cl和Br）的同一多组分配合物中时，发现了一种有趣的协同效应。两种相互作用均显示出正协同效应，表现为更大的相互作用能、更短的键间距和更大的电子密度。四元键的增强取决于阴离子 - π相互作用的强度，其增强顺序为Br < Cl < F。四元键的增强使其性质从纯粹的闭壳层相互作用转变为部分共价相互作用。相反，阴离子 - π相互作用显示出高达 - 38 kcal mol的显著增强。已根据静电势和电荷转移对这种效应进行了分析。
