Elucidating the Binding Modes of N‑Heterocyclic Carbenes on a Gold Surface
journal contributionposted on 2018-09-11, 00:00 authored by Anne Bakker, Alexander Timmer, Elena Kolodzeiski, Matthias Freitag, Hong Ying Gao, Harry Mönig, Saeed Amirjalayer, Frank Glorius, Harald Fuchs
Tuning the binding mode of N-heterocyclic carbenes on metal surfaces is crucial for the development of new functional materials. To understand the impact of alkyl side groups on the formation of NHC species at the Au(111) surface, we combined scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. We reveal two significantly different binding modes depending on the alkyl chain length. In the case of a short alkyl substituent, an up-standing configuration with one Au adatom is preferred, whereas the longer alkyl groups result exclusively in NHC-Au-NHC complexes lying flat on the surface. Our study highlights how well-defined structural modifications of NHCs allow for controlling the local binding motif on surfaces, which is important to design designated catalytic sites at interfaces.
N-heterocyclic carbenestheory calculationsalkyl substituentGold Surface TuningNHC-Au-NHC complexesbinding modesscanning tunneling microscopyNHC speciesBinding Modesbinding modeX-ray photoelectron spectroscopyalkyl groups resultup-standing configurationmetal surfacesbinding motifalkyl chain lengthalkyl side groups