Formation of XNCO species (X = F, Cl) through matrix-isolation photochemistry of XSO2NCO molecules
The photochemistries of the molecules ClSO2NCO and FSO2NCO isolated in solid argon matrices at ∼10 K have been investigated. After photolysis of the matrices with broad-band UV–visible radiation (200 ≤ λ ≤ 800 nm) the products were identified by their IR spectra. ClSO2NCO decomposes in two steps. In the first place, the photolysis gives a 1:1 molecular complex between SO2 and ClNCO. In the second step, ClNCO decomposes in different parallel photochemical channels to give ClNO, NO, CO and the ClCO· radical, while SO2, transformed from a complexed to an uncomplexed form, remains stable on photolysis. The SO2:ClNCO molecular complex was theoretically investigated by ab initio and DFT methods. Based on the comparison with the experimental findings, a structure in which the lone pair of one of the oxygen atoms of the SO2 unit interacts with the unoccupied σ*Cl–N orbital of ClNCO was proposed. On the other hand, FSO2NCO remains almost photostable when exposed to similar conditions, with the only formation of FNCO and CO in very small proportions.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Photolysis of ClSO2NCO in argon matrix forms the SO2:ClNCO molecular complex. ► ClNCO is an intermediate product in the photolysis of matrix isolated ClSO2NCO. ► FSO2NCO is more stable than ClSO2NCO when exposed to UV–visible radiation.
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 223, Issues 2–3, 25 September 2011, Pages 194–201