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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Bond-forming reactions of dications with molecules: A computational and experimental study of the mechanisms for the formation of HCF2+ from CF32+ and H-2
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Bond-forming reactions of dications with molecules: A computational and experimental study of the mechanisms for the formation of HCF2+ from CF32+ and H-2

机译：药物与分子的键形成反应：由CF32 +和H-2形成HCF2 +的机理的计算和实验研究

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The QCISD and QCISD(T) quantum chemical methods have been used to characterize the energetics of various possible mechanisms for the formation of HCF2+ from the bond-forming reaction of CF32+ with H-2. The stationary points on four different pathways leading to the product combinations HCF2+ + H+ + F and HCF2+ HF+ have been calculated. All four pathways begin with the formation of a collision complex [H-2-CF3](2+), followed by an internal hydrogen atom migration to give HC(FH)F-2(2+). In two of the mechanisms, immediate charge separation of HC(FH)F-2(2+) via loss of either HF+ or a proton, followed by loss of an F atom, yields the experimentally observed bond-forming product HCF2+. For the other two mechanisms, internal hydrogen rearrangement of HC(FH)F-2(2+) to give C(FH)(2)F2+, followed by charge separation, yields the product CF2H+. This product can then overcome a 2.04 eV barrier to rearrange to the HCF2+ isomer, which is 1.80 eV more stable. All four calculated mechanisms are in agreement with the isotope effects and collision energy dependencies of the product ion cross sections that have been previously observed experimentally following collisions between CF32+ and H-2/D-2. We find that in this open-shell system, CCSD(T) and QCISD(T) T-1-diagnostic values of up to 0.04 are acceptable. A series of angularly resolved crossed-beam scattering experiments on collisions of CF32+ with D-2 have also been performed. These experiments show two distinct channels leading to the formation of DCF2+. One channel appears to correspond to the pathway leading to the ground state (DCF2+)-D-1 + D+ + F product asymptote and the other to the (DCF2+)-D-3 + D+ + F product asymptote, which is 5.76 eV higher in energy. The experimental kinetic energy releases for these channels, 7.55 and 1.55 eV respectively, have been determined from the velocities of the DCF2+ product ion and are in agreement with the reaction mechanisms calculated quantum chemically. We suggest that both of these observed experimental channels are governed by the reaction mechanism we calculate in which charge separation occurs first by loss of a proton, without further hydrogen atom rearrangement, followed by loss of an F atom to give the final products (DCF2+)-D-1 + D+ + F or (DCF2+)-D-3 + D+ + F.
机译：QCISD和QCISD（T）量子化学方法已用于表征由CF32 +与H-2的键形成反应形成HCF2 +的各种可能机理的能量学。已计算出导致产品组合HCF2 + + H + + F和HCF2 + HF +的四个不同路径上的固定点。所有四个途径均以形成碰撞配合物[H-2-CF3]（2+）开始，然后发生内部氢原子迁移，从而生成HC（FH）F-2（2+）。在两种机理中，HC（FH）F-2（2+）通过失去HF +或质子立即电荷分离，然后失去F原子，产生了实验观察到的成键产物HCF2 +。对于其他两个机理，HC（FH）F-2（2+）的内部氢重排得到C（FH）（2）F2 +，然后进行电荷分离，生成了产物CF2H +。然后，该产品可以克服2.04 eV的障碍，以重新排列为HCF2 +异构体，后者稳定1.80 eV。所有四种计算的机理都与先前在CF32 +和H-2 / D-2之间发生碰撞后通过实验观察到的产物离子截面的同位素效应和碰撞能量依赖性相一致。我们发现在这种开放式系统中，可接受的CCSD（T）和QCISD（T）T-1诊断值最高为0.04。还进行了一系列关于CF32 +与D-2碰撞的角度分辨交叉光束散射实验。这些实验显示了导致DCF2 +形成的两个不同通道。一个通道似乎对应于导致基态（DCF2 +）-D-1 + D + + F产物渐近线的路径，而另一个通道对应于（DCF2 +）-D-3 + D + + F产物渐近线，后者高5.76 eV在能量上。这些通道的实验动能释放分别为7.55和1.55 eV，这是根据DCF2 +产物离子的速度确定的，并且与量子化学计算的反应机理相符。我们建议这两个观察到的实验通道均受我们计算出的反应机理支配，其中电荷分离首先通过质子的损失发生，而没有进一步的氢原子重排，然后是F原子的损失以产生最终产物（DCF2 +） -D-1 + D ++ F或（DCF2 +）-D-3 + D ++ F.

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