Theoretical study on the singlet and triplet potential energy surfaces of NH (X~3Σ~-) + HCNO reaction

摘要

Both the singlet and triplet potential energy surfaces (PESs) of the NH (X~3Σ~-) + HCNO reaction have been investigated at the BMC-CCSD level based on the UB3LYP/6-311++G(d, p) structures. The results show that the title reaction is more favorable through the singlet potential energy surface than the triplet one. For the singlet potential energy surface of the NH (X~3Σ~-) + HCNO reaction, the most feasible association of NH (X~3Σ~-) with HCNO is found to be a non-barrier nitrogen-to-carbon attack forming the adduct a (trans-HNCHNO), which can isomerize to the adduct b (cis-HNCHNO). The most feasible channel is that the 1, 3-H shift with N2-H2 and C-Nl bonds cleavage associated with the N1-H2 bond formation of adduct a leads to the product P1 (HCN + HNO). Moreover, P2 (HNC + HNO) should be the competitive product. The other products, including P3 (NH2 + NCO) and P4 (N2H2 + CO), are minor products. The product P1 can be obtained through two competitive channels Path 1: R → a→ P1 and Path 3: R → b→ d → P1, whereas the product P2 can be formed through Path 2: R → b → d → P2. At high temperatures, the nitrogen-to-nitrogen approach may become feasible. For the triplet potential energy surface of the NH (X~3Σ~-) + HCNO reaction, the Path 10: R , →~3a; →~ 3a1 → P1 should be the most feasible pathway due to the less reaction steps and lower barriers. These conclusions will have impacts on further experimental investigations.