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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Theoretical Study of the Reactions of H Atoms with CH3I and CH2I2
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Theoretical Study of the Reactions of H Atoms with CH3I and CH2I2

机译：H原子与CH3I和CH2I2反应的理论研究

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High level ab initio methods have been used to provide reliable kinetic data for the H + CH3I and H + CH2I2 gas-phase reactions. The (H, I)-abstraction and I-substitution reaction pathways were identified. The structures were determined on the potential energy surface at the MP2/aug-cc-pVTZ level of theory. The energetics was then refined using the coupled cluster theory. For the iodinated species, the spin-orbit coupling was calculated using the MRCI approach. The core valence and the scalar relativistic corrections were considered. Thermal rate constants were reported using the canonical transition-state theory (TST) and compared to computed values with the canonical variational transition-state theory (CVT) using the zero curvature tunneling (ZCT) and the small curvature tunneling (SCT) corrections over a wide temperature range (250-2500 K) to show the importance of quantum tunneling effects at low temperatures. They are given by the following expressions for the overall reactions using the CVT/SCT method: k(H+CH3I)(T) = 1.07 X 10(-17) X T-2.13 exp(2.68 (kJ mol(-1))/RT) and k(H+CH2I2)(T) = 5.73 X 10(-21) X T-2.97 exp(3.15 (kJ mol(-1))/RT). The I-abstraction is predicted to be the major pathway for both H + CH3I and H + CH2I2 reactions. The obtained kinetic parameters for the H + CH3I reaction are in excellent agreement with their experimental counterparts over the temperature range 300-750 K. On the basis of our calculated reaction enthalpies, a new evaluation of the standard enthalpy of formation at 298 K of CH2I and CHI2 has been provided. Obtained values are Delta H-f degrees(298K) (CH2I) = 219.5 kJ mol(-1) and Delta H-f degrees(298K)(CHI2) = 296.3 kJ mol(-1).
机译：高级AB初始方法已用于为H + CH 3I和H + CH 2 I2气相反应提供可靠的动力学数据。鉴定了（H，I） - Abstraction和I-替代反应途径。在MP2 / AUG-CC-PVTZ理论水平的潜在能量表面上确定结构。然后使用耦合的集群理论精制能量。对于碘化物种，使用MRCI方法计算自旋轨道耦合。考虑了核心价和标量相同的校正。报告使用规范转换状态理论（TST）的热速率常数，并与使用零曲率隧道（ZCT）和小曲率隧道（SCT）校正的Consonical变分过渡状态理论（CVT）与计算值相比宽温度范围（250-2500 k），以显示在低温下量子隧道效应的重要性。使用以下表达式给出了使用CVT / SCT方法的整体反应的表达：K（H + CH3I）（T）= 1.07×10（-17）x T-2.13 exp（2.68（KJ Mol（-1）） / RT）和K（H + CH 2 I2）（T）= 5.73×10（-21）×T-2.97 exp（3.15（kj mol（-1））/ Rt）。预计I抽象预计是H + CH3I和H + CH2I2反应的主要途径。对于H + CH3I反应的获得的动力学参数与其在300-750k的温度范围内的实验对应物非常一致。在我们计算的反应焓的基础上，在CH2I的298k的298k中对形成标准焓的新评估并提供了CHI2。获得的值是δH-F度（298K）（CH2I）= 219.5 kJ摩尔（-1）和Delta H-F度（298K）（CHI2）= 296.3 kJ摩尔（-1）。

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