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首页> 外文期刊>Crystal growth & design >Contribution of Different Crystal Packing Forces in pi-Stacking: From Noncovalent to Covalent Multicentric Bonding
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Contribution of Different Crystal Packing Forces in pi-Stacking: From Noncovalent to Covalent Multicentric Bonding

机译：不同晶体包装力在PI堆叠中的贡献：从非价到共价多中心键合

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摘要

The present review is aimed to compare crystal packing interactions contributing to stacking arrangements of primarily nonaromatic systems referring only briefly to classical aromatic stacking. The classical aromatic stacking is mainly based on weak dispersion interactions (E <= 1 kcal mol (-1)) whereas heteroaromatics reveal more electrostatic (or specifically dipolar) contributions (E = 5-10 kcal mol(-1)). Based mainly on our charge density studies and DFT calculations, the results show that (i) all planar rings stack, regardless of aromaticity (or delocalization of pi electrons) and (ii) stacking interactions cover a wide continuum ranging from weak, mainly dispersion interactions (E < 5 kcal mol(-1)) to unlocalized two-electron multicentric (2e/mc) covalent bonds ("pancake bonds", E > 15 kcal mol -1 ). Our recent studies showed that quinones form face-to-face stacks and the energies of interactions exceed 10 kcal mol(-1); ours and other authors' results indicate that interactions between planar radicals involve a significant contribution of covalent bonding. Thus, pi-interactions cover a broad range of energies, ranging from <= 1 to >= 20 kcal mol(-1), and the interactions span from weak dispersion to multicentric covalent bonding. Therefore, development of a universal model of stacking is needed. In this respect, stacking can be compared to hydrogen bonding, which also ranges between dispersion (weakest hydrogen bonds, such as C-H center dot center dot center dot S and C-H center dot center dot center dot Cl) and two-electron/three-centric covalent bonding (the strongest "symmetrical" hydrogen bonds).
机译：本综述旨在比较水晶包装相互作用，这些交互对于主要是非芳族系统的堆叠布置，仅向古典芳族堆叠提及。经典芳族堆叠主要基于弱分散相互作用（E <= 1千岩摩尔（-1））而杂芳烃揭示了更多的静电（或特异性偶极）贡献（E = 5-10kcal（-1））。主要基于我们的电荷密度研究和DFT计算，结果表明（i）所有平面环堆叠，无论芳香性（或Pi电子的临近化）和（ii）堆叠相互作用覆盖宽度较弱，主要是色散相互作用（e <5千卡Mol（-1））到未均透明的双电子多中心（2E / MC）共价键（“煎饼键”，E> 15千卡Mol -1）。我们最近的研究表明，Quinones形成面对面的堆叠，相互作用的能量超过10千卡（-1）;我们和其他作者的结果表明，平面自由基之间的相互作用涉及共价键的显着贡献。因此，PI-相互作用覆盖了广泛的能量，范围为<= 1至> = 20千卡摩尔（-1），并且相互作用跨度从弱分散到多中心共价键合。因此，需要开发普遍模型的堆叠模型。在这方面，可以将堆叠与氢键相比，该氢键也可以在色散（最弱的氢键，例如CH中心点中心DOT中心点S和CH中心点中心点CL）之间的范围和两个电子/三合一共价键合（最强“对称的”氢键）。

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