Imaging single-molecule reaction intermediates stabilized by surface dissipation and entropy

A. Riss, A. P. Paz, S. Wickenburg, H.-Z. Tsai, D. G. De Oteyza, A. J. Bradley, M. M. Ugeda, P. Gorman, H. S. Jung, M. F. Crommie, A. Rubio, F. R. Fischer

Department of Physics, University of California, Berkeley, CA 94720, U. S. A.
Institut für Angewandte Physik, Technische Universität Wien, 1040 Wien, Austria
Nano-Bio Spectroscopy Group and ETSF, Universidad del País Vasco, 20018 San Sebastián, Spain
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, U. S. A.
Donostia International Physics Center, 20018 San Sebastián, Spain
Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
Centro de Física de Materiales CSIC/UPV-EHU-Materials Physics Center, 20018 San Sebastián, Spain
CIC nanoGUNE, 20018 San Sebastián, Spain
Department of Chemistry, University of California, Berkeley, California 94720, U. S. A.
Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, U. S. A.
Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
Center for Free-electron Laser Science (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany

Nat. Chem. 8 (2016) 678-683

Chemical transformations at the interface between solid/liquid or solid/gaseous phases of matter lie at the heart of key industrial-scale manufacturing processes. A comprehensive study of the molecular energetics and conformational dynamics that underlie these transformations is often limited to ensemble-averaging analytical techniques. Here we report the detailed investigation of a surface-catalysed cross-coupling and sequential cyclization cascade of 1,2-bis(2-ethynyl phenyl)ethyne on Ag(100). Using non-contact atomic force microscopy, we imaged the single-bond-resolved chemical structure of transient metastable intermediates. Theoretical simulations indicate that the kinetic stabilization of experimentally observable intermediates is determined not only by the potential-energy landscape, but also by selective energy dissipation to the substrate and entropic changes associated with key transformations along the reaction pathway. The microscopic insights gained here pave the way for the rational design and control of complex organic reactions at the surface of heterogeneous catalysts.

Corresponding authors: Alexander Riss, Michael F. Crommie, Angel Rubio, and Felix R. Fischer

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