利用自由射流吸收毫米波光谱研究2-羟基苯乙酮的分子结构与内部动力学

Molecular Structure and Internal Dynamics of 2-Hydroxyacetophenone by Free-Jet Absorption Millimeter-Wave Spectroscopy.

作者信息

Boi Salvatore, Melandri Sonia, Evangelisti Luca, Maris Assimo

机构信息

Department of Chemistry G. Ciamician, University of Bologna, 40126 Bologna, Italy.

Interdepartmental Centre for Industrial Aerospace Research (CIRI Aerospace), University of Bologna, 47521 Cesena, Italy.

出版信息

Molecules. 2024 Dec 11;29(24):5842. doi: 10.3390/molecules29245842.

DOI:10.3390/molecules29245842

PMID:39769933

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC11677718/

Abstract

The rotational spectrum of 2'-hydroxyacetophenone has been recorded and assigned for the first time using a Stark-modulated free-jet absorption millimeter-wave (FJ-AMMW) spectrometer in the 59.6-74.5 GHz frequency range. The most stable conformer has been detected and assigned: = 2277.076(11), = 1212.113(5) and = 795.278(5) MHz. It is characterized by a Cs symmetry where a strong hydrogen bond between the acetyl oxygen atom and the hydroxyl atom takes place. The transition lines show a fine structure due to the internal rotation of the methyl group, which allowed the determination of a V3 = 565.1(5) cm-1 barrier. The corresponding tunneling splittings have been estimated to be 51 MHz. Calculations at the B3LYP-D3(BJ)/Def2-TZVP level underestimate the height of the barrier by about 156 cm-1. This value decreases to 25 cm-1 with MP2/aug-cc-pVTZ.

摘要

首次使用斯塔克调制自由射流吸收毫米波（FJ - AMMW）光谱仪在59.6 - 74.5 GHz频率范围内记录并归属了2'-羟基苯乙酮的转动光谱。检测并归属了最稳定的构象体： = 2277.076(11)、 = 1212.113(5)和 = 795.278(5) MHz。其特征为具有Cs对称性，其中乙酰基氧原子与羟基原子之间形成了强氢键。由于甲基的内旋转，跃迁线呈现出精细结构，据此确定了一个V3 = 565.1(5) cm-1的势垒。相应的隧穿分裂估计为51 MHz。在B3LYP - D3(BJ)/Def2 - TZVP水平的计算低估了势垒高度约156 cm-1。使用MP2/aug - cc - pVTZ时，该值降至25 cm-1。