Lash Miller Chemical Laboratories, Department of Chemistry, University of Toronto, Ontario, Canada.
J Am Chem Soc. 2012 Jun 6;134(22):9320-6. doi: 10.1021/ja301608q. Epub 2012 May 22.
Halogenation at a semiconductor surface follows simple dynamics characterized by "localized reaction" along the direction of the halide bond being broken. Here we extend the study of halide reaction dynamics to the important environment of a smooth metal surface, where greater product mobility would be expected. Extensive examination of the physisorbed reagent and chemisorbed products from two successive electron-induced reactions showed, surprisingly, that for this system product localization and directionality described the dynamics at a metal. The reagent was p-diiodobenzene on Cu(110) at 4.6 K. The first C-I bond-breaking yielded chemisorbed iodophenyl and I-atom(#1), and the second yielded phenylene and I-atom(#2). The observed collinear reaction resulted in secondary encounters among products, which revealed the existence of a surface-aligned reaction. The molecular dynamics were well explained by a model embodying a transition between an a priori ground state and a semiempirical ionic state, which can be generally applied to electron-induced chemical reactions at surfaces.
在半导体表面的卤化反应遵循简单的动力学特征，表现为卤键断裂方向上的“局部反应”。在这里，我们将卤化物反应动力学的研究扩展到一个平滑金属表面的重要环境中，在这个环境中，预计会有更大的产物迁移率。对两种连续电子诱导反应的物理吸附试剂和化学吸附产物的广泛研究表明，令人惊讶的是，对于这个体系，产物的定位和方向性描述了金属表面的动力学。试剂是在 4.6 K 下的 Cu(110)上的对二碘苯。第一个 C-I 键的断裂生成了化学吸附的碘苯和 I-原子（#1），第二个生成了苯和 I-原子（#2）。观察到的共线反应导致产物之间的二次碰撞，这揭示了表面对齐反应的存在。分子动力学很好地解释了一个模型，该模型体现了从先验基态到半经验离子态的转变，这可以普遍应用于表面上的电子诱导化学反应。
