Abstract The review presents a critical analysis of the data obtained from vibrational spectroscopic studies on a narrow selection of weak hydrogen-bonded binary molecular complexes for measurements performed under isolated conditions, addressing the nature, properties, physical origins of the binding forces, and the role of such hydrogen bonds in dynamics of vibrational relaxations. In the recent history of studies of chemical bonding, hydrogen bond certainly occupies the centre stage. Although the bottom line of our knowledge for structure of hydrogen bonded systems is based on crystallographic data, it is well recognised that the constrained environment of a molecular crystal seriously perturbs the shallow interaction potentials of hydrogen bonds, and particularly their weaker variants. Binary complexes of different categories of molecular prototypes are the most convenient systems to look into the attributes and role played by the weak hydrogen bonds in promoting a chemically significant event. A variety of weak hydrogen bonded binary complexes, having mostly two types of binding motifs, CH··O and OH⋯π, have been considered for this review. The vital molecular parameter that has been primarily considered in the present analysis is the hydrogen bond induced spectral shift (ΔνΧ-Η) of the stretching vibrational fundamental of the donor group (X–H), for measurements performed in inert gas matrixes and also in the gas phase. The changes in infrared spectral band shapes of νX–H transitions have been considered to suggest the influence of the hydrogen bond in vibrational dynamics of the excited X–H stretching mode. Attempts are made to correlate the observed spectral shifts in homologous series of complexes for a particular binding motif with different energetic and electronic structure parameters, and those correlations have been used to get insights into the underlying molecular interactions and origin of vibrational spectral shifts. The other vital parameters of binary molecular complexes are the low-frequency intermolecular vibrations, which appear typically in terahertz range of the electromagnetic spectrum. A brief analysis of the available data for weak hydrogen bonded complexes, obtained by employing LIF spectroscopic method, is presented, and information obtained from complementary spectroscopic methods, like far-infrared absorption, are discussed. The spectral data presented are mostly from the published work of the authors.

中文翻译：

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弱氢键：来自振动光谱研究的见解

摘要 该评论对从振动光谱研究中获得的数据进行了批判性分析，这些研究对在孤立条件下进行测量的一系列弱氢键合二元分子复合物进行了分析，解决了结合力的性质、性质、物理起源和作用。这种氢键在振动弛豫动力学中的作用。在最近的化学键研究史上，氢键无疑占据了中心位置。尽管我们对氢键系统结构的认识的底线是基于晶体学数据，但众所周知，分子晶体的受限环境严重扰乱了氢键的浅层相互作用势，尤其是它们较弱的变体。不同类别分子原型的二元复合物是研究弱氢键在促进化学重要事件中的属性和作用的最方便的系统。本综述考虑了各种弱氢键二元复合物，主要具有两种类型的结合基序，CH··O 和 OH⋯π。在本分析中主要考虑的重要分子参数是供体基团 (X-H) 的伸缩振动基波的氢键诱导光谱位移 (ΔνΧ-H)，用于在惰性气体基质中进行的测量以及在气相。νX–H 跃迁的红外光谱带形状的变化已被认为表明氢键对激发的 X–H 拉伸模式的振动动力学的影响。尝试将在同源系列复合物中观察到的光谱位移与具有不同能量和电子结构参数的特定结合基序相关联，并且这些相关性已被用于深入了解潜在的分子相互作用和振动光谱位移的起源。二元分子复合物的其他重要参数是低频分子间振动，通常出现在电磁波谱的太赫兹范围内。简要分析了使用 LIF 光谱方法获得的弱氢键配合物的可用数据，并讨论了从补充光谱方法（如远红外吸收）获得的信息。提供的光谱数据主要来自作者发表的作品。