Forming N-heterocyclic carbene monolayers: not all deposition methods are the same
Aruna Chandran, Nathaniel L. Dominique, Gurkiran Kaur, Vincent Clark, Phattananawee Nalaoh, Lilian Chinenye Ekowo, Isabel M. Jensen, Mark D. Aloisio, Cathleen M. Crudden, Netzahualcóyotl Arroyo‐Currás, David M. Jenkins, Jon P. Camden
Abstract
adduct, the bicarbonate salt, or the triflate salt. The resulting surfaces are characterized with surface-enhanced Raman spectroscopy (SERS), laser desorption/ionization mass spectrometry (LDI-MS), electrochemistry, and X-ray photoelectron spectroscopy (XPS). These data indicate that the free carbene, vacuum annealing, and solvent annealing methods form chemisorbed NHC monolayers, as expected; however, the solution phase methods without annealing yield surfaces with a fundamentally different character. Although XPS is widely used to confirm the binding of NHCs to metal surfaces, it does not capture the differences in these deposition procedures and should be used with caution. Taken together, these results reveal a significant variation of the NHC surface structure as a function of deposition procedure and provide a critical benchmark to govern the design and preparation of future NHC monolayer systems.