Meitei Oinam Romesh, Heßelmann Andreas
Lehrstuhl für Theoretische Chemie, Universität Erlangen-Nürnberg, Egerlandstr. 3, Erlangen, D-91058, Germany.
J Comput Chem. 2017 Nov 5;38(29):2500-2508. doi: 10.1002/jcc.24908. Epub 2017 Aug 7.
A molecular fragmentation method has been used to analyze the intramolecular interactions in the three molecules coupled diamantane, hexaphenylethane, and all-meta-tert-butyl substituted hexaphenylethane. The significance of these systems lies in the fact, that steric crowding effects enable a stabilization of the central carbon bond that possesses an extended length (1.6 to 1.7 Å) beyond conventional carbon-carbon bonds due to the steric repulsion of the attached hydrocarbon groups. The total stability of these molecules therefore depends on a delicate balance between attractive interaction forces on the one hand and on repulsive forces on the other hand. We have quantified the different interaction energy contributions using symmetry-adapted perturbation theory based on a density functional theory description of the monomers. It has been found that the attractive dispersion interactions increase more strongly with the level of crowding in the systems than the counteracting exchange interactions. This shows that steric crowding effects can have a significant impact on the structure and stability of large and branched molecules. © 2017 Wiley Periodicals, Inc.
一种分子碎片化方法已被用于分析偶联金刚烷、六苯基乙烷和全间位叔丁基取代六苯基乙烷这三种分子中的分子内相互作用。这些体系的重要性在于，由于连接的烃基的空间排斥作用，空间拥挤效应能够使中心碳 - 碳键稳定，该键具有超出传统碳 - 碳键的延长长度（1.6至1.7 Å）。因此，这些分子的整体稳定性取决于一方面吸引力相互作用和另一方面排斥力之间的微妙平衡。我们基于单体的密度泛函理论描述，使用对称适配微扰理论对不同的相互作用能贡献进行了量化。已发现，与起抵消作用的交换相互作用相比，吸引性色散相互作用随体系中拥挤程度的增加更为强烈。这表明空间拥挤效应可对大的支化分子的结构和稳定性产生重大影响。© 2017威利期刊公司。
