Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada.
Phys Chem Chem Phys. 2020 Oct 21;22(40):23019-23027. doi: 10.1039/d0cp03329d.
The 1 : 1 adduct of 2,2,2-trifluoroethanol (TFE) with ammonia was investigated using a combination of chirped pulse and cavity-based Fourier transform microwave spectroscopy and computational methods. Rotational spectra of the most stable TFENH3 conformer and seven deuterium and 15N isotopologues were identified, and this led to a determination of partial rs and ro structures. The observed complex exhibits a gauche conformation of TFE with ammonia inserted into the existing intramolecular hydrogen-bonded ring of TFE. The adduct is stabilised by a delicate interplay between the primary O-HN hydrogen-bond and secondary N-HF interactions between TFE and ammonia. Evidence for several internal-dynamics effects was found in the rotational spectra. The ammonia subunit shows an almost free internal rotation. Tunneling between the gauche forms, g+ and g-, of TFE is quenched by the hydrogen-bond interactions with ammonia.
采用啁啾脉冲和基于腔的傅里叶变换微波光谱学以及计算方法研究了 2,2,2-三氟乙醇（TFE）与氨的 1:1 加合物。鉴定了最稳定的 TFENH3 构象以及 7 个氘代和 15N 同位素异构体的转动光谱，从而确定了部分 rs 和 ro 结构。观察到的复合物表现出 TFE 的 gauche 构象，氨插入 TFE 中现有的分子内氢键环中。加合物通过 TFE 和氨之间的主要 O-HN 氢键和次要 N-HF 相互作用之间的微妙相互作用得到稳定。在转动光谱中发现了几种内部动力学效应的证据。氨亚基表现出几乎自由的内部旋转。TFE 的 gauche 形式 g+和 g-之间的隧道相互作用被与氨的氢键相互作用所抑制。
