论文标题
表面促进的Ullmann耦合期间卤素激活的层次结构
Hierarchy in the halogen activation during surface-promoted Ullmann coupling
论文作者
论文摘要
在当前可以在超高真空下生产扩展分子纳米结构的表面支撑反应的集合中，Ullmann耦合在共价单C-C键的控制形成中是最成功的。该合成工具的特别高级控制是通过分层反应性获得的，通常通过使用不同的卤素原子来实现，从而表现出不同的激活温度。在这里，我们报告了某些碳释放键的位点选择性反应性。我们使用在两个非等效碳原子上用溴原子卤素的前体分子，发现ullmann偶联发生在AU（111）上，其中一个位置具有显着的偏见。实验证据是通过扫描隧道显微镜的方法提供的，对观察到的偏好的合理理解是从密度功能理论计算中获得的。
Within the collection of surface-supported reactions currently accessible for the production of extended molecular nanostructures under ultra-high vacuum, Ullmann coupling has been the most successful in the controlled formation of covalent single C-C bonds. Particularly advanced control of this synthetic tool has been obtained by means of hierarchical reactivity, commonly achieved by the use of different halogen atoms that consequently display distinct activation temperatures. Here we report on the site-selective reactivity of certain carbon-halogen bonds. We use precursor molecules halogenated with bromine atoms at two non-equivalent carbon atoms and found that the Ullmann coupling occurs on Au(111) with a remarkable predilection for one of the positions. Experimental evidence is provided by means of scanning tunneling microscopy and a rationalized understanding of the observed preference is obtained from density functional theory calculations.
