Zhang Lijuan, Pei Ling, Li Dazhi, Bian He
College of Chemical Engineering and Safety Engineering, Shandong University of Aeronautics, Binzhou, Shandong 256600, China.
J Phys Chem A. 2024 Aug 22;128(33):6898-6907. doi: 10.1021/acs.jpca.4c03370. Epub 2024 Aug 13.
To deeply understand the characteristics and regulation of red/blue-shifting hydrogen bonds (HBs), a theoretical investigation was conducted to explore the cooperativity between regium bonds and HBs in the complexes of Y···MCN···HCX (M = Cu, Ag, Au; Y = HO, HCN, NH; X = F, Cl). When MCN formed a hydrogen bonding dimer with CHF or CHCl, the blue shift of C-H vibration frequency (C-H) decreases as the following sequence Au > Cu > Ag, and the red shift decreases following the order Ag > Cu > Au. Upon the formation of ternary complexes, the presence of regium bonding interactions exerts a positive synergistic effect, resulting in the strengthening of the HBs. This, in turn, leads to noticeable changes in the red and blue shifts of (C-H). In CHF complexes, (C-H) undergoes a decrease in the blue shift, whereas that in CHCl exhibits an increase in the red shift. Especially, a transition from blue to red shift is observed within the AuCN···HCCl complex. As the strength of the regium bond increases, the trend of shifting from blue to red becomes more pronounced. For a given MCN, the changes occur in the order of NH > HCN > HO. The interplay between two interactions was revealed by the molecular electrostatic potentials (MEP), the atoms in the molecule (AIM), and natural bond orbitals (NBO) analysis. It is revealed that Δ(C-H) is linearly correlated with a series of configuration and energy parameters. We explain the red- and blue-shifting HBs and their changes from the perspective of hyperconjugation and rehybridization. The presence of the positive synergistic effect enhances the hyperconjugation effect, thereby leading to a reduction in the blue shift and an increase in the red shift of (C-H) within the complexes. This study enriches previous mechanisms regarding red- and blue-shifting HBs and introduces a novel idea to manipulate the characteristics of HBs, with the potential to impact the functioning of intricate systems.
为了深入了解红移/蓝移氢键（HBs）的特性和调控机制，进行了一项理论研究，以探索Y···MCN···HCX（M = Cu、Ag、Au；Y = HO、HCN、NH；X = F、Cl）配合物中regium键与HBs之间的协同作用。当MCN与CHF或CHCl形成氢键二聚体时，C-H振动频率（C-H）的蓝移按Au > Cu > Ag的顺序减小，红移按Ag > Cu > Au的顺序减小。形成三元配合物后，regium键相互作用的存在产生了正协同效应，导致HBs增强。这反过来又导致（C-H）的红移和蓝移发生显著变化。在CHF配合物中，（C-H）的蓝移减小，而在CHCl配合物中，红移增加。特别是，在AuCN···HCCl配合物中观察到从蓝移到红移的转变。随着regium键强度的增加，从蓝移到红移的转变趋势变得更加明显。对于给定的MCN，变化按NH > HCN > HO的顺序发生。通过分子静电势（MEP）、分子中的原子（AIM）和自然键轨道（NBO）分析揭示了两种相互作用之间的相互作用。结果表明，Δ（C-H）与一系列构型和能量参数呈线性相关。我们从超共轭和再杂化的角度解释了红移和蓝移HBs及其变化。正协同效应的存在增强了超共轭效应，从而导致配合物中（C-H）的蓝移减小和红移增加。本研究丰富了以往关于红移和蓝移HBs的机制，并引入了一种操纵HBs特性的新思路，有可能影响复杂系统的功能。
