Department of Chemistry and Centre for Scientific Modeling and Computation Chinese University of Hong Kong, Shatin, Hong Kong, China.
Phys Chem Chem Phys. 2011 May 28;13(20):9871-9. doi: 10.1039/c0cp02187c. Epub 2011 Apr 19.
The icosahedral Al is a "magic" cluster with remarkable stability due to its high symmetry and closed valence shells. Its reactivity has provided a molecular model for understanding oxidation and dissolution processes in bulk metals. By first principles calculations, we demonstrated the importance of dynamic factors in the Al + HX reactions, with HX being either HCl or HI. There was a barrier to the dissociative adsorption of HX on the surface of an Al cluster, which involved charge transfer from Al. Furthermore, the H atom could be bonded to the cluster in multiple ways, similar to the top, bridge and hollow adsorption sites on Al(111) surface. With a large amount of energy (∼40 kcal mol(-1)) deposited during the formation of Al(13)HX(-), the H atom could easily migrate among these sites, similar to the diffusion of hydrogen on metal surfaces. These factors were therefore important considerations in the formation and dissociation of Al(13)HX(-), and more generally in reactions involving other metal clusters.
二十面体的 Al 是一个“神奇”的团簇，由于其具有高对称性和封闭的价壳层，因此具有显著的稳定性。其反应活性为理解块状金属中的氧化和溶解过程提供了一个分子模型。通过第一性原理计算，我们证明了在 Al + HX 反应（HX 为 HCl 或 HI）中动态因素的重要性。HX 在 Al 团簇表面的离解吸附存在一个势垒，涉及 Al 的电荷转移。此外，H 原子可以以多种方式与团簇键合，类似于 Al(111)表面的顶、桥和中空吸附位。在 Al(13)HX(-)形成过程中沉积了大量能量（约 40 kcal mol(-1))，H 原子可以在这些位置之间轻易迁移，类似于氢在金属表面的扩散。因此，这些因素对于 Al(13)HX(-)的形成和解离以及更一般地涉及其他金属团簇的反应都是重要的考虑因素。
