Computational Study on Reaction Mechanisms of Isocyanocarbene with NO

• Main Authors: Li, CiJhen, 李奇蓁
• Other Authors: Chen, HuiLung
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/91171135562836161406

碩士 === 中國文化大學 === 應用化學研究所 === 99 === The mechanisms of the reaction of the Isocyanocarbene radical (HCNC) with the NO have been investigated by ab initio molecular orbital method. The relevant stationary points and potential energy surfaces (PESs) were calculated by the B3LYP/6-311++G(3df,2p) and CCSD(T)/6-311++G(3df,2p)//B3LYP/6-311G(3df,2p) levels, respectively. Products P2 (HCNO + CN) and P3 (HCN + NCO) are two leading channels with slight energy barriers as compared to the reactants HCNC + NO. In the former path (P2 formation), HCNC and NO undergo bond addition reaction and then produce IM3 with exothermicity of 61.49 kcal/mol. It will then overcome a barrier height of 12.32 kcal/mol (via TSiso1) forming an intermediate, IM2. The IM2 can directly produce the final products P2 (HCNO + CN) via one variational transition state with an overall exothermicity of 12.68 kcal/mol as compared to the reactants HCNC + NO. For the path of P3 formation, however, the IM3 intermediate will proceed another pathway, via TS2 (Ea=21.45 kcal/mol), to form five-membered ring intermediate, IM7, and then open the ring by passing a barrier (via TS5, 6.31 kcal/mol) forming another intermediate, IM9. The IM9 will break its C-N bond (via TS7, 53.39 kcal/mol) and form the final products of P3 (HCN + NCO), with an overall exothermicity of 98.63 kcal/mol. To effetely rationalize the scenario of the calculated results, we also employ the Fukui functions and HSAB theory to seek for the possible explanation of the aforementioned phenomena.