Pancake Bonding Seen through the Eyes of Spectroscopy
Pancake Bonding Seen through the Eyes of Spectroscopy
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DOI：
10.5772/intechopen.99747
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发表时间：
2021-10
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影响因子：
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通讯作者：
A. A. A. Delgado-A.-A.;Alan W. Humason;E. Kraka
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文献类型：
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作者：
A. A. A. Delgado-A.-A.;Alan W. Humason;E. Kraka
通过在UM06/6 - 311G（d，p），UM06/SDD，UM05 - 2X/6 - 31 ++ G（d，p）水平上计算的局域模伸缩力常数和拓扑电子密度分析，我们阐明了平行π堆积相互作用的性质和强度1，2-二硫杂-3，5-二唑基二聚体、1，2-二硒杂-3，5-二唑基二聚体、1，2-碲杂-3，5-二唑基二聚体、非那烯基二聚体、2，5，8-三甲基非那烯基二聚体和2，5，8-三叔丁基非那烯基二聚体的键合（即饼键合）。我们使用本地模式的拉伸力常数，以获得一个芳香性离域指数（AI）的phenalenyl为基础的二聚体和它们的单体，以确定取代和二聚化对芳香性的影响，以及确定什么键的性质支配芳香性的改变。我们的研究结果表明，C C接触的强度和环的二-chalcadiazoyl二聚体的调查减少平行减少硫族元素的硫族元素键强度。能量密度值Hb表明1，2-二硫杂-3，5-二唑基二聚体和1，2-二硒杂-3，5-二唑基二聚体的S-S和Se-Se饼键本质上是共价键。我们观察到的煎饼债券，所有phenalenyl为基础的二聚体的调查，是静电的性质。与它们的单体对应物相反，基于非那烯基的二聚体的芳香性增加主要是由于CC键强化。对于基于苯并萘基的二聚体，我们观察到，大体积取代基的加入稳定地降低了系统的芳香性，主要是由于CC键弱化。
From local mode stretching force constants and topological electron density analysis, computed at either the UM06/6-311G(d,p), UM06/SDD, or UM05-2X/6–31++G(d,p) level of theory, we elucidate on the nature/strength of the parallel π-stacking interactions (i.e. pancake bonding) of the 1,2-dithia-3,5-diazolyl dimer, 1,2-diselena-3,5-diazolyl dimer, 1,2-tellura-3,5-diazolyl dimer, phenalenyl dimer, 2,5,8-tri-methylphenalenyl dimer, and the 2,5,8-tri-t-butylphenalenyl dimer. We use local mode stretching force constants to derive an aromaticity delocalization index (AI) for the phenalenyl-based dimers and their monomers as to determine the effect of substitution and dimerization on aromaticity, as well as determining what bond property governs alterations in aromaticity. Our results reveal the strength of the C⋯C contacts and of the rings of the di-chalcodiazoyl dimers investigated decrease in parallel with decreasing chalcogen⋯chalcogen bond strength. Energy density values Hb suggest the S⋯S and Se⋯Se pancake bonds of 1,2-dithia-3,5-diazolyl dimer and the 1,2-diselena-3,5-diazolyl dimer are covalent in nature. We observe the pancake bonds, of all phenalenyl-based dimers investigated, to be electrostatic in nature. In contrast to their monomer counterparts, phenalenyl-based dimers increase in aromaticity primarily due to CC bond strengthening. For phenalenyl-based dimers we observed that the addition of bulky substituents steadily decreased the system aromaticity predominately due to CC bond weakening.