Department of Physical Chemistry, Faculty of Chemistry, University of Łódź, Pomorska 163/165, 90236 Łódź, Poland.
Institut de Química Computacional I Catàlisi, Departament de Química, Universitat de Girona, C/Ma Aurèlia Capmany, 69, 17003 Girona, Spain.
Int J Mol Sci. 2021 Dec 26;23(1):233. doi: 10.3390/ijms23010233.
In the presented research, we address the original concept of resonance-assisted hydrogen bonding (RAHB) by means of the many-body interaction approach and electron density delocalization analysis. The investigated molecular patterns of RAHBs are open chains consisting of two to six molecules in which the intermolecular hydrogen bond stabilizes the complex. Non-RAHB counterparts are considered to be reference systems. The results show the influence of the neighbour monomers on the unsaturated chains in terms of the many-body interaction energy contribution. Exploring the relation between the energy parameters and the growing number of molecules in the chain, we give an explicit extrapolation of the interaction energy and its components in the infinite chain. Electron delocalization within chain motifs has been analysed from three different points of view: three-body delocalization between C=C-C, two-body hydrogen bond delocalization indices and also between fragments (monomers). A many-body contribution to the interaction energy as well as electron density helps to establish the assistance of resonance in the strength of hydrogen bonds upon the formation of the present molecular chains. The direct relation between interaction energy and delocalization supports the original concept, and refutes some of the criticisms of the RAHB idea.
在本研究中，我们通过多体相互作用方法和电子密度离域分析来研究共振辅助氢键（RAHB）的原始概念。研究的 RAHB 分子模式是由两个到六个分子组成的开链，其中分子间氢键稳定了复合物。非 RAHB 对应物被视为参考系统。结果表明，邻单体对不饱和链的多体相互作用能量贡献的影响。通过研究能量参数与链中分子数量的关系，我们给出了无限长链中相互作用能及其分量的明确外推。从三个不同的角度分析了链中电子离域：C=C-C 之间的三体离域、氢键的二体离域指数以及片段（单体）之间的离域。相互作用能和电子密度的多体贡献有助于确定在形成目前的分子链时，共振对氢键强度的辅助作用。相互作用能和离域之间的直接关系支持了原始概念，并反驳了对 RAHB 概念的一些批评。
