RESUMO
The first diiron(iii,iv)-µ2-oxo tetracarbene complex is isolated and characterized by SC-XRD, UV/Vis, EPR, Evans' NMR and elemental analysis. CV indicates the presence of a transient high-valent diiron(iv)-µ2-oxo species. Its formation and decay is investigated via UV/Vis kinetics and NMR.
Assuntos
Materiais Biomiméticos/química , Complexos de Coordenação/química , Enzimas/metabolismo , Ferro/química , Metano/análogos & derivados , Cinética , Metano/química , Modelos Moleculares , Conformação MolecularRESUMO
The first dicobalt(III) µ2 -peroxo N-heterocyclic carbene (NHC) complex is reported. It can be quantitatively generated from a cobalt(II) compound bearing a 16-membered macrocyclic tetra-NHC ligand via facile activation of dioxygen from air at ambient conditions. The reaction proceeds via an end-on superoxo intermediate as demonstrated by EPR studies and DFT. The peroxo moiety can be cleaved upon addition of acetic acid, yielding the corresponding CoIII acetate complex going along with H2 O2 formation. In contrast, both CoII and CoIII complexes are also studied as catalysts to utilize air for olefin and alkane oxidation reactions; however, not resulting in product formation. The observations are rationalized by DFT-calculations, suggesting a nucleophilic nature of the dicobalt(III) µ2 -peroxo complex. All isolated compounds are characterized by NMR, ESI-MS, elemental analysis, EPR and SC-XRD.
