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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Arene-cation interactions of positive quadrupole moment aromatics and arene-anion interactions of negative quadrupole moment aromatics
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Arene-cation interactions of positive quadrupole moment aromatics and arene-anion interactions of negative quadrupole moment aromatics

机译：正四极矩芳族化合物的芳烃阳离子相互作用和负四极矩芳族化合物的芳烃阴离子相互作用

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Intermolecular interactions involving aromatic pi-electron density are widely believed to be governed by the aromatic molecular quadrupole moment, Theta(zz). Arene-cation binding is believed to occur primarily with negative Theta(zz) aromatics, and arene-anion binding is believed to occur largely with positive Theta(zz) aromatics. We have performed quantum mechanical computations that show the cation binding of positive Theta(zz) aromatics and the anion binding of negative Theta(zz) aromatics is quite common in the gas phase. The pi-electron density of hexafluorobenzene, the prototypical positive Theta(zz) aromatic (experimental Theta(zz) = +9.5 +/- 0.5 D angstrom), has a Li+ binding enthalpy of -4.37 kcal/mol at the MP2(full)/6-311G** level of theory. The RHF/6-311G** calculated Theta(zz) value of 1,4-dicyanobenzene is +11.81 D angstrom, yet it has an MP2(full)/6-311G**Li+ binding enthalpy of -12.65 kcal/mol and a Na+ binding enthalpy of -3.72 kcal/mol. The pi-electron density of benzene, the prototypical negative Theta(zz) aromatic (experimental Theta(zz) = -8.7 +/- 0.5 D angstrom), has a F- binding enthalpy of -5.51 kcal/mol. The RHF/6-311G** calculated Theta(zz) of C6H2I4 is -10.45 D angstrom, yet it has an MP2(full)/6-311++G** calculated F- binding enthalpy of -20.13 kcal/mol. Our results show that as the aromatic Theta(zz) value increases the cation binding enthalpy decreases; a plot of cation binding enthalpies versus aromatic Theta(zz) gives a line of best of fit with R-2 = 0.778. No such correlation exists between the aromatic Theta(zz) value and the anion binding enthalpy; the line of best fit has R-2 = 0.297. These results are discussed in terms of electrostatic and polarizability contributions to the overall binding enthalpies.
机译：人们普遍认为，涉及芳香族π电子密度的分子间相互作用受芳香族分子四极矩Theta（zz）支配。认为芳族阳离子键主要与负的Theta（zz）芳族化合物发生，而芳烃-阴离子键主要与正的Theta（zz）芳族化合物发生。我们已经进行了量子力学计算，显示出正的Theta（zz）芳族化合物的阳离子结合和负的Theta（zz）芳族化合物的阴离子结合在气相中非常普遍。六氟苯的pi电子密度，典型的正Theta（zz）芳香族（实验性Theta（zz）= +9.5 +/- 0.5 D埃），在MP2处的Li +结合焓为-4.37 kcal / mol。 / 6-311G **理论水平。 RHF / 6-311G **计算得出的1,4-二氰基苯的Theta（zz）值为+11.81 D埃，但其MP2（full）/ 6-311G ** Li +的结合焓为-12.65 kcal / mol， Na +结合焓为-3.72 kcal / mol。苯的π电子密度是原型负的Theta（zz）芳香族化合物（实验性Theta（zz）= -8.7 +/- 0.5 D埃），其F结合焓为-5.51 kcal / mol。 RHF / 6-311G **计算得出的C6H2I4的Theta（zz）为-10.45 D埃，但其MP2（完全）/ 6-311 ++ G **计算得出的F结合焓为-20.13 kcal / mol。我们的结果表明，随着芳香族Theta（zz）值的增加，阳离子结合焓降低;阳离子结合焓与芳香族Theta（zz）的关系图给出了最佳拟合线，其中R-2 = 0.778。芳香族Theta（zz）值与阴离子结合焓之间不存在这种相关性;最佳拟合线的R-2 = 0.297。根据静电和极化率对总结合焓的贡献讨论了这些结果。

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