LAUSR

Abstract The decomposition of copper(I)–NHC and silver-NHC complexes in solution under air was studied. The Cu(I)–NHCs were oxidized into urea derivatives and hydrolysed into imidazoliums or benzimidazoliums. The decomposition of Ag–NHC with a saturated backbone led to ring-opening product, while the Ag–NHC with an unsaturated backbone led to imidazolium and Ag-bisNHC complex. The effects of steric property, hydrophilicity, and binding energy of NHC to O2 and H2O on the decomposition of Cu(I)–NHC were studied using theoretical calculations. Steric hindrance played an important role on the stability of Cu(I)–NHC. Pathways for the decomposition of Cu(I)–NHC and Ag–NHC were proposed.