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O: Fachverband Oberflächenphysik

O 11: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures I

O 11.7: Vortrag

Montag, 12. März 2018, 17:00–17:15, MA 004

Precise mono-selective aromatic C-H activation by chemisorption of meta-aryne on a metal surface — •Qitang Fan¹, Simon Werner¹, Jalmar Tschakert², Daniel Ebeling², André Schirmeisen², Wolfgang Hieringer³, and J. Michael Gottfried¹ — ¹Fachbereich Chemie, Philipps-Universität Marburg, Germany — ²Institute of Applied Physics (IAP), Justus Liebig University Gießen, Germany — ³Lehrstuhl für Theoretische Chemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany

Aromatic C-H activation has attracted much attention due to their wide range of applications in the synthesis of aryl-containing chemicals. The major challenge lies in the minimization of the activation barrier and maximization of the regioselectivity. Here, we report the Cu(111) surface-catalyzed highly-selective activation of the C-H bond between two meta-substituted C-Br groups anchored on a phenyl ring. Two prototype molecules, i.e., 4',6'-dibromo-meta-terphenyl and 3',5'-dibromo-ortho-terphenyl have been employed to perform reactions on Cu(111). The chemical structures of the resulted products have been clarified by the combination of scanning tunneling microscopy and non-contact atomic force microscopy. Both of them demonstrate a remarkable weakening of the C-H bond between the two C-Br groups. Density function theory reveals that this efficient C-H activation stems from the extraordinary chemisorption of the meta-aryne, which leads to the close proximity of the targeted C-H bond to the Cu(111) surface and the out-of-plane deformation of the phenyl ring. These findings pave the way for new types of C-H activation approaches.