Multicomponent QM study on the reaction of HOSO + NO₂ with H₂O: Nuclear quantum effect on structure and reaction energy profile

Abstract

The hydrogen transfer reaction in the reaction of HOSO + NO2 with and without H2O have been investigated using multicomponent quantum‐mechanics method, which can directly take nuclear quantum effect (NQE) of light nuclei into account. For the case of the reaction without H2O, our calculation reveals that the reaction leading to trans‐HONO is preferred. For the reaction with H2O, water‐non‐mediated and water‐mediated (hydrogen‐relay) hydrogen transfer mechanism are investigated. The NQE of hydrogen nucleus lowers the relative energy of the stationary point structures and reduces the activation barrier of the reactions. The largest stabilization is found in the transition state structure of the hydrogen‐relay type reaction. H/D isotope effects for the reactions are also analyzed. In particular, H/D isotope effect on the activation barrier is analyzed in detail with the aid of the active strain model.

Photochemistry and Non-adiabatic Photodynamics of the HOSO Radical

“…Since its first experimental identification in 1996 by Frank et al, the molecular properties and reactivity of the hydroxysulfinyl radical (HOSO) have been extensively studied − to understand its role as a key intermediate in sulfur-related processes such as the catalytic removal of chain-propagating radicals , or the formation of sulfur dioxide (SO 2 ) in hot molecular cores . This radical has also gained increasing attention over the past few years because of its potential role in atmospheric chemistry. ,,− ,− HOSO can be generated from SO 2 upon excitation at 250−340 nm, followed by the population of its lowest excited triplet state via intersystem crossing (). , This highly reactive 3 SO 2 species can abstract a H atom from water in the gas phase (), yielding HOSO and a OH radical, in a process favored by partial water solvation in the air–water interface. , …”

Oxidation of HOSO˙ by O2 (3Σg−): a key reaction deciding the fate of HOSO˙ in the atmosphere

“…[11][12][13] The importance of HOSO comes from its ambient reactivity towards various oxidizing agents present in the atmosphere. In the last few years, there are a few studies [14][15][16][17][18][19][20] on the oxidation of HOSO by various oxidizing agents like H, OH , Cl , NO 2 , NH 2 , etc., where SO 2 is obtained as a final product. The aim of the present work is to study the reaction of HOSO with O 2 ( 3 S g À ) and assess its potential impact on the atmosphere.…”

“…11–13 The importance of HOSO˙ comes from its ambient reactivity towards various oxidizing agents present in the atmosphere. In the last few years, there are a few studies 14–20 on the oxidation of HOSO˙ by various oxidizing agents like H, OH˙, Cl˙, NO 2 , NH 2 ˙, etc. , where SO 2 is obtained as a final product.…”

A New Mechanism of Acid Rain Generation from HOSO at the Air–Water Interface

“…Further work has confirmed that the reaction mechanism involves a proton-coupled electron-transfer mechanism that is favored by water solvation, so the activation free energy at the air–water interface is predicted to be low (<1 kcal·mol –1 at 298 K) and the triplet is predicted to be rapidly hydrolyzed . The atmospheric chemistry of HOSO is poorly known, though some studies in the gas phase have been reported. ,,− …”