复旦大学曾小庆团队报道了HONO光化学反应中HOON中间体的直接观察。相关研究成果发表在2024年7月13日出版的《美国化学会杂志》上。

亚硝酸（HONO）的光化学，包括分解成OH和NO以及反向缔合反应，在大气化学中起着关键作用。

该文中，研究人员报告了使用基质分离红外和紫外-可见光谱，直接观察HONO光化学中的亚硝基-O-氢氧化物（HOON）。尽管存在约30 kJ/mol的势垒，但HOON通过量子力学隧穿自发重排为更稳定的HONO异构体，在4 K下的半衰期为28分钟。

动力学同位素效应和瞬子理论计算表明，隧穿过程涉及NO部分（65.2%）和氢原子（32.3%）的协同运动。研究结果强调了HOON作为低温下HONO光解解离-缔合循环中关键中间体的重要性。

附：英文原文

Title: Direct Observation of HOON Intermediate in the Photochemistry of HONO

Author: Xiaolong Li, Wenbin Fan, Lina Wang, Junjie Jiang, Yanqi Du, Wei Fang, Tarek Trabelsi, Joseph S. Francisco, Jiawei Yang, Jun Li, Mingfei Zhou, Xiaoqing Zeng

Issue&Volume: July 13, 2024

Abstract: The photochemistry of nitrous acid (HONO), encompassing dissociation into OH and NO as well as the reverse association reaction, plays a pivotal role in atmospheric chemistry. Here, we report the direct observation of nitrosyl-O-hydroxide (HOON) in the photochemistry of HONO, employing matrix-isolation IR and UV–vis spectroscopy. Despite a barrier of approximately 30 kJ/mol, HOON undergoes spontaneous rearrangement to the more stable HONO isomer through quantum mechanical tunneling, with a half-life of 28 min at 4 K. Kinetic isotope effects and instanton theory calculations reveal that the tunneling process involves the concerted motion of the NO moiety (65.2%) and the hydrogen atom (32.3%). Our findings underscore the significance of HOON as a key intermediate in the photolytic dissociation–association cycle of HONO at low temperatures.

DOI: 10.1021/jacs.4c06851

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c06851