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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Experimental and Computational Study of Hydration Reactions of Aluminum Oxide Anion Clusters
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Experimental and Computational Study of Hydration Reactions of Aluminum Oxide Anion Clusters

机译：氧化铝阴离子团簇水化反应的实验与计算研究

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Hydration of aluminum oxide anion clusters was studied in the gas phase using an ion trap secondary ion mass spectrometer. Hydration of both AlO_2~- and Al_2O_4H~- occurred by the consecutive addition of two H_2O molecules. For hydration of AlO_2~-, the rate constants for addition of the first and second water molecules are 4×10~(-11) and 4×10~(-10) cm~3 molecule~(-1) s~(-1), respectively. The first and second hydration rate constants for Al_2O_4H~- are 2×10~(-9) and 8×10~(-10) cm~3 molecule~(-1) s~(-1), respectively. A comparison of the experimental rate constants to the theoretical rate constants reveals that addition of the first H_2O to AlO_2~- is only 2% efficient, whereas addition of the first H_2O to Al_2O_4H~- is 100% efficient. Ab initio calcualtions were performed to assist in the interpretation of the kinetic results. Reaction mechanisms and energetics for the hydration of the AlO_2~- system were calculated using the HF/6-311+G(d(Al),p), B3LYP/6-31+G(d), B3LYP/6-311+G(2d,p), B3LYP/6-311+G(3d2f,2p), and MP2/6-311+G(2d,p) levels of theory. Calculations on the hydration of the Al_2O_4H~- system were performed using the B3LYP/6-311+G(2d,p) level of theory. Ab initio results revealed that the addition of the first and second water, for both the AlO_2~- and Al_2O_4H~- systems, results in the formation of four-membered transition states, with simultaneous Al-O bond formation and proton transfer. However, a significant later transition state is observed, with respect to the Al-O and H-O bond lengths, for the addition of the second water molecule in the Al_2O_4H~- system. A comparison of the reaction mechanisms and energetics was not sufficient to account for the 2 orders of magnitude difference in rate constants; however, the reactivity differences do correlate with the dipole moment of the aluminum oxide anions, which may serve to preorient the incoming water molecule, thus enhancing the reaction rate.
机译：使用离子阱二次离子质谱仪研究了气相中氧化铝阴离子簇的水合。 AlO_2〜-和Al_2O_4H〜-的水合是通过连续添加两个H_2O分子而实现的。对于水合AlO_2〜-，添加第一和第二水分子的速率常数为4×10〜（-11）和4×10〜（-10）cm〜3分子〜（-1）s〜（- 1）。 Al_2O_4H〜-的第一和第二水合速率常数分别为2×10〜（-9）和8×10〜（-10）cm〜3分子〜（-1）s〜（-1）。实验速率常数与理论速率常数的比较表明，将第一H_2O添加到AlO_2〜-的效率仅为2％，而将第一H_2O添加到Al_2O_4H〜-的效率为100％。从头进行计算以帮助解释动力学结果。使用HF / 6-311 + G（d（Al），p），B3LYP / 6-31 + G（d），B3LYP / 6-311 +计算AlO_2〜-系统水合的反应机理和能量学G（2d，p），B3LYP / 6-311 + G（3d2f，2p）和MP2 / 6-311 + G（2d，p）的理论水平。使用B3LYP / 6-311 + G（2d，p）的理论值对Al_2O_4H〜-系统的水合作用进行了计算。从头算结果表明，对于AlO_2〜-和Al_2O_4H〜-系统，添加第一和第二水会导致四元过渡态的形成，同时形成Al-O键和质子转移。然而，对于在Al_2O_4H〜-系统中添加第二水分子而言，相对于Al-O和H-O键的长度，观察到明显的后期过渡态。反应机理和能量学的比较不足以说明速率常数的两个数量级差异。然而，反应性差异确实与氧化铝阴离子的偶极矩相关，这可以用来预定向进入的水分子，从而提高反应速率。

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