The work reports a study of the properties of tautomeric O–H⋯O hydrogen bonding (τ-bonding). The Raman spectra of crystalline and polycrystalline samples of terephthalic acid chains, benzoic acid dimers, and ibuprofen dimers are studied in the temperature region of 5-300 K. The protons on τ-bonds in terephthalic acid and ibuprofen are substituted by deuterium. Temperature dependences of the frequencies of τ-bond translational vibrations are analyzed, their relation to tunneling and proton hopping is discussed. It is shown that the propagation of the proton (deuteron) density distribution function into the neighboring empty potential well increases hydrogen bonding, while physical motion of the particle through the barrier or hopping over the barrier affect the ω(T) dependence of the vibration of the C=O bond in the τ-ring. On the example of ibuprofen, asymmetric τ-bonds are analyzed and the energy difference between L- and R-tautomers are measured.

中文翻译：

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互变异构 O–H⋯O 氢键的拉曼光谱研究

该工作报告了对互变异构 O-H⋯O 氢键（τ-键合）性质的研究。在 5-300 K 的温度范围内研究了对苯二甲酸链、苯甲酸二聚体和布洛芬二聚体的结晶和多晶样品的拉曼光谱。对苯二甲酸和布洛芬中的 τ 键上的质子被氘取代。分析了τ键平移振动频率的温度依赖性，讨论了它们与隧穿和质子跳跃的关系。结果表明，质子（氘核）密度分布函数传播到相邻的空势阱中会增加氢键，而粒子穿过势垒或跳过势垒的物理运动会影响振动的 ω(T) 依赖性。 τ-环中的 C=O 键。