Theoretical Study on the Reaction of Nitric Oxide with Propargyl Radical

The reaction of nitric oxide (NO) with propargyl radical (C3H3) was investigated at the CCSD(T)/cc-pVTZ//B3LYP/6-311++G(df, pd) level of theory. The rate coefficients of the system were determined by using the RRKM–CVT method with Eckart tunneling correction over a temperature range of 200–800 K and a pressure range of 1.0 × 10–4 to 10.0 bar. Eight channels proceeding via the barrierless formation of excited intermediate ONCH2CCH or CH2CCHNO at the first step were explored. Three favorable channels (i.e., channels producing adduct of ONCH2CCH and CH2CCHNO and products of HCN and H2CCO) were confirmed. The rate coefficients of channels producing adduct of ONCH2CCH and CH2CCHNO are comparable and have weak negative temperature dependence and positive pressure dependence. Channel producing products of HCN and H2CCO is more important at low pressure and high temperature and less important after pressure greater than 1.0 × 10–2 bar (with a branching ratio less than 6% at 0.1 bar).