Density functional study on the ClCOÂ +Â NO2 reaction

Various reaction pathways on the potential energy surface for the ClCO + NO2, radicals which are both known to be upper atmosphere pollutants, were investigated at the B3LYP level of theory using the 6-311G(d) and 6-311+G(3df) basis sets. The energetics were refined with G3//B3LYP and CBS-QB3 calculations. The following reaction channels between the two are the most probable: (i) the formation of ClNO + CO2 or ClON + CO2 via cis-trans ClC(O)ONO or cis-cis ClC(O)ONO intermediates, respectively, and (ii) the formation of the low-lying adduct trans-trans ClC(O)ONO. The other adduct ClC(O)NO2 is calculated to lie about 20 kcal mol−1 higher in energy than trans-trans ClC(O)ONO. Thus, trans-trans ClC(O)ONO can be considered to be a sink for ClCO radical on the ground-state surface.