Morozov Alexander N, Mebel Alexander M
Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
Phys Chem Chem Phys. 2020 Apr 6;22(13):6868-6880. doi: 10.1039/d0cp00306a.
Potential energy surface for the phenyl + propargyl radical recombination reaction has been studied at the CCSD(T)-F12/cc-pVTZ-f12//B3LYP/6-311G** level of theory for the closed-shell singlet species and at the triplet-singlet gap CASPT2/cc-pVTZ-CCSD(T)-F12/cc-pVTZ-f12//CASSCF/cc-pVTZ level of theory for the diradical species. High-pressure limit rate constants for the barrierless channels were evaluated with variable reaction coordinate transition state theory (VRC-TST). Rice-Ramsperger-Kassel-Marcus Master Equation (RRKM-ME) calculations have been performed to assess temperature- and pressure-dependent phenomenological rate constants and product branching ratios. The entrance channels of the radical association reaction produce 3-phenyl-1-propyne and phenylallene which can further dissociate/isomerize into a variety of unimolecular and bimolecular products. Theoretical evidence is presented that, at combustion relevant conditions, the phenyl + propargyl recombination provides a feasible mechanism for the addition of a second five-member ring to the first six-member aromatic ring producing the prototype two-ring species indene and indenyl. Rate expressions for all important reaction channels in a broad range of temperatures and pressures have been generated for kinetic modeling.
在CCSD(T)-F12/cc-pVTZ-f12//B3LYP/6-311G**理论水平下研究了苯基+炔丙基自由基复合反应的势能面，用于闭壳单重态物种；在三重态-单重态能隙CASPT2/cc-pVTZ-CCSD(T)-F12/cc-pVTZ-f12//CASSCF/cc-pVTZ理论水平下研究了双自由基物种的势能面。使用可变反应坐标过渡态理论（VRC-TST）评估了无障碍通道的高压极限速率常数。进行了Rice-Ramsperger-Kassel-Marcus主方程（RRKM-ME）计算，以评估温度和压力依赖的唯象速率常数及产物分支比。自由基缔合反应的入口通道生成3-苯基-1-丙炔和苯并戊二烯，它们可进一步解离/异构化为各种单分子和双分子产物。有理论证据表明，在燃烧相关条件下，苯基+炔丙基复合反应为向第一个六元芳环添加第二个五元环生成原型二环物种茚和茚基提供了一种可行的机制。已生成了广泛温度和压力范围内所有重要反应通道的速率表达式，用于动力学建模。
