Computational study on mechanisms and pathways of the atmospheric NH2 + IO reaction. (2nd April 2020)

• Record Type: Journal Article
• Authors: Zhang, Yunju; Tang, Yizhen; Sun, Jingyu
• Is Part Of: Molecular physics. Volume 118:Number 7(2020)
• Publication Date: 2020-04-02
• Subjects: NH2 -- IO -- PES -- reaction mechanism -- RRKM-TST; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2019.1658908
• Languages: English
• ISSNs: 0026-8976

Abstract

ABSTRACT: The potential-energy surfaces of the amino radical (NH2 ) with IO reaction have been studied at the CCSD(T)/cc-pVTZ//MP2/6-311++G(d, p) level. Two kinds of pathways are revealed, namely H-abstraction and addition/elimination. Rice–Ramsperger–Kassel–Marcus theory and transition state theory are employed to calculate the overall and individual rate constants over a wide range of temperatures and pressures. It is predicted that, at atmospheric pressure with N2 as bath gas, the formation of P1 (HI + HNO) is the dominant pathways at 200–700 K, while the direct H-abstraction leading to P3 ( 3 NH + HOI) takes over the reaction at a temperature above 700 K. At the high-pressure limit, IM1 [IONH2 ] formed by collisional stabilisation is dominant at 200–700 K; the direct H-abstraction resulting in P3 ( 3 NH + HOI) plays an important role at higher temperatures. However, the total rate constants are independence on the pressure; however, the individual rate constants are sensitive to pressure. The atmospheric lifetime of NH2 in IO is around one week. TD-DFT computations imply that IM1 [IONH2 ], IM1A [IONH2 ′], IM2 [IN(H2 )O], IM3 [OINH2 ], IM4 [HOINH], tra -IM5 [ tra -HON(H)I] and cis -IM5 [ cis -HON(H)I] will photolyze under the sunlight. GRAPHICAL ABSTRACT: