biostudies-literatureGhavami ZSDeutsche Forschungsgemeinschaft8307-8314https://www.ebi.ac.uk/biostudies/studies/S-EPMC6240905biostudies-literatureUnknown9(43)For years, Cu(iii)NHCs have been proposed as active intermediates in Cu(i)NHC catalyzed reactions, yielding the desired products by reductive elimination, but until today, no one has ever reported the characterisation of such a compound. When working on the synthesis of biomimetic transition metal (NHC) complexes and their application in homogeneous catalysis, we recently found a highly unusual reactivity for Cu(ii) acetate in the presence of a particular cyclic tetra(NHC) ligand. Therein, the formation of the first stable CuNHC compound, displaying Cu in the formal oxidation state +III, by simple disproportionation of Cu(ii) acetate in dimethyl sulfoxide (DMSO) was observed. At elevated temperatures selective mono-oxidation of the NHC ligand occurs, even under anaerobic conditions. AcetatChemical scienceA bench stable formal Cu(iii) <i>N</i>-heterocyclic carbene accessible from simple copper(ii) acetate.PMC6240905IRTG 2022Ghavami ZSKaiser FAltmann PJKuhn FESchlagintweit JFHofmann BJAnneser MRGrivani GfalseA bench stable formal Cu(iii) <i>N</i>-heterocyclic carbene accessible from simple copper(ii) acetate.For years, Cu(iii)NHCs have been proposed as active intermediates in Cu(i)NHC catalyzed reactions, yielding the desired products by reductive elimination, but until today, no one has ever reported the characterisation of such a compound. When working on the synthesis of biomimetic transition metal (NHC) complexes and their application in homogeneous catalysis, we recently found a highly unusual reactivity for Cu(ii) acetate in the presence of a particular cyclic tetra(NHC) ligand. Therein, the formation of the first stable CuNHC compound, displaying Cu in the formal oxidation state +III, by simple disproportionation of Cu(ii) acetate in dimethyl sulfoxide (DMSO) was observed. At elevated temperatures selective mono-oxidation of the NHC ligand occurs, even under anaerobic conditions. Acetat2018-01-01T00:00:00Z2018 Nov2026-05-06T04:01:52.26Z2019-10-30T08:14:16ZS-EPMC62409053054257910.1039/c8sc01834k