N‐Heterocyclic Carbenes Reduce and Functionalize Copper Oxide Surfaces in One Pot

Benzimidazolium hydrogen carbonate salts have been shown to act as N‐heterocyclic carbene precursors, which can remove oxide from copper oxide surfaces and functionalize the resulting metallic surfaces in a single pot. Both the surfaces and the etching products were fully characterized by spectroscopic methods. Analysis of surfaces before and after NHC treatment by X‐ray photoelectron spectroscopy demonstrates the complete removal of copper(II) oxide. By using 13C‐labelling, we determined that the products of this transformation include a cyclic urea, a ring‐opened formamide and a bis‐carbene copper(I) complex. These results illustrate the potential of NHCs to functionalize a much broader class of metals, including those prone to oxidation, greatly facilitating the preparation of NHC‐based films on metals other than gold. Monolayers: For the first time, a simultaneous etch‐functionalize protocol has been developed for oxidized copper surfaces using N‐heterocyclic carbenes. These results demonstrate the dual functionality of N‐heterocyclic carbenes when applied to more reactive metal surfaces that are prone to oxidation and offers a new strategy for chemical etching that avoids dangerous reagents. This work also provides an opportunity to replace precious metals, such as gold, with more abundant metals, such as copper, in organic‐on‐metal devices.