高温下单分子解离反应中芳香族三聚体配合物的动力学行为。C6H6–C6F6–C6H6 和 C6H6 三聚体配合物的案例研究,The Journal of Physical Chemistry A

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高温下单分子解离反应中芳香族三聚体配合物的动力学行为。C6H6–C6F6–C6H6 和 C6H6 三聚体配合物的案例研究
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2022-01-07 , DOI: 10.1021/acs.jpca.1c09073
Himashree Mahanta ₁ , Amit Kumar Paul ₁

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高温下芳香族三聚体单分子解离过程中的分子内振动能量再分布（IVR）动力学是本研究的主要兴趣。对苯-六氟苯-苯 (Bz-HFB-Bz) 和苯三聚体 (Bz-trimer) 配合物在 1000–2000 K 温度范围内的单分子解离进行化学动力学模拟。观察到两种配合物的部分解离，这导致动力学中的二聚体和单体。然而，在 Bz-三聚体的情况下，这种解离的可能性要低得多，随着温度的升高，这种解离的可能性会进一步降低。Bz-HFB-Bz 的部分解离速率在 1500、1800 和 2000 K 时更快，而 Bz-三聚体的完全解离速率在所有温度下都明显快于 Bz-HFB-Bz。这与相应的二聚体解离正好相反，其中苯-六氟苯 (Bz-HFB) 的解离速度比苯二聚体 (Bz-二聚体) 快。因此，三聚体的解离动力学不同于二聚体的解离动力学。对三聚体配合物的激发分子内和分子间模式的模拟表明，能量从 Bz-HFB-Bz 的分子间模式流向分子内模式比 Bz-三聚体更自由，并且前者的解离过程变慢。两种动力学的计算活化能都远低于相应的结合能，这可能是由于非谐性造成的。考虑使用具有非谐波校正因子的 Arrhenius 方程来重新计算活化能和指前因子。

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Dynamical Behavior of Aromatic Trimer Complexes in Unimolecular Dissociation Reaction at High Temperatures. Case Studies on C6H6–C6F6–C6H6 and C6H6 Trimer Complexes

The intramolecular vibrational energy redistribution (IVR) dynamics during unimolecular dissociation of aromatic trimers at high temperatures is the primary interest of this study. Chemical dynamics simulations are performed for the unimolecular dissociation of benzene–hexafluorobenzene–benzene (Bz-HFB-Bz) and benzene trimer (Bz-trimer) complexes at a temperature range of 1000–2000 K. Partial dissociation of both the complexes is observed, which leads to a dimer and a monomer in the dynamics. However, the probability of such dissociation was found much lower in the case of the Bz-trimer, which further decreases with the increase of temperature. The rate of partial dissociation of Bz-HFB-Bz is faster at 1500, 1800, and 2000 K, whereas the rate of complete dissociation of the Bz-trimer is significantly faster than Bz-HFB-Bz at all temperatures. This is just the opposite of the corresponding dimer’s dissociation, where benzene–hexafluorobenzene (Bz-HFB) dissociates at a faster rate than the benzene dimer (Bz-dimer). Thus, the dissociation dynamics of the trimer is different than that of the dimer. Simulations with excited intramolecular and intermolecular modes of the trimer complexes reveal that energy flows from intermolecular to intramolecular modes of Bz-HFB-Bz more freely than the Bz-trimer, and the dissociation process becomes slower for the former. Calculated activation energies for both types of dynamics are much lower than the corresponding binding energies, which may be due to the anharmonicity. The Arrhenius equation with an anharmonic correction factor is considered to recalculate the activation energy and pre-exponential factor.

更新日期：2022-01-20

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