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

Chemistry. 2020 Sep 4;26(50):11431-11434. doi: 10.1002/chem.202002308. Epub 2020 Aug 7.

Abstract

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 13 C-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.

Keywords: NMR spectroscopy; carbenes; copper; monolayers; photoelectron spectroscopy.