Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
J Phys Chem A. 2023 Jun 1;127(21):4660-4669. doi: 10.1021/acs.jpca.3c01480. Epub 2023 May 20.
The reaction of atomic carbon, C(P), with HCO has been investigated using the direct dynamics trajectory surface hopping (DDTSH) method with Tully's fewest switches algorithm. The lowest lying ground triplet and single states are considered for the dynamics study at a reagent collision energy of 8.0 kcal/mol. From the trajectory calculations, we observed that CH + CO and H + HCCO are the two major product channels for the title reaction. The insertion mechanism of the C(P) + HCO reaction is rather complex and is followed by three distinct intermediates with no entrance channel barrier to the reaction on the B3LYP/6-31G(d,p) potential energy surfaces. The triplet insertion complexes are formed by three different approaches; "Sideways", "End-on" and "Head-on" attack of the triplet carbon atom toward HCO molecule. Our dynamics calculations predict a new product channel (H + HCCO(X A'')) with a contribution of ∼46% of the overall products formation via ketocarbene intermediate through "Head-on" approach. Despite the weak spin-orbit coupling (SOC) interactions, intersystem crossing (ISC) via a ketocarbene intermediate has a small but significant contribution, about 2.3%, for the CH + CO channel. To understand the kinetic isotope effects on the reaction dynamics, we have extended our study for the C(P) + DCO reaction. It is seen that isotopic substitution of both the H atoms has a small reduction in the extent of ISC dynamics for the carbene formation. Our results, certainly, reveal the importance of the ketocarbene intermediate and the H + HCCO products channel as one of the major product formation channels in the title reaction, which was not reported earlier.
采用直接动力学轨迹表面跳跃（DDTSH）方法和 Tully 的最少开关算法，研究了原子碳 C(P)与 HCO 的反应。在试剂碰撞能为 8.0 kcal/mol 的情况下，考虑了最低的三重态和单重态进行动力学研究。从轨迹计算中，我们观察到 CH + CO 和 H + HCCO 是标题反应的两个主要产物通道。C(P) + HCO 反应的插入机制相当复杂，在 B3LYP/6-31G(d,p)势能表面上，没有进入通道的势垒。三重态插入复合物通过三种不同的方法形成：三重态碳原子对 HCO 分子的“侧”、“端”和“头”攻击。我们的动力学计算预测了一个新的产物通道（H + HCCO(X A''))，通过“头”攻击通过酮卡宾中间体形成的总产物的贡献约为 46%。尽管自旋轨道耦合（SOC）相互作用较弱，但通过酮卡宾中间体的系间窜越（ISC）对 CH + CO 通道有很小但很重要的贡献，约为 2.3%。为了了解反应动力学的同位素效应，我们扩展了对 C(P) + DCO 反应的研究。可以看出，两个 H 原子的同位素取代对卡宾形成的 ISC 动力学有很小的影响。我们的结果当然揭示了酮卡宾中间体和 H + HCCO 产物通道的重要性，它们是标题反应中主要产物形成通道之一，这在以前的报道中没有提到。
