Access to divalent lanthanide NHC complexes by redox-transmetallation from silver and CO2 insertion reactions

Abstract

Through a redox-transmetallation procedure, divalent NHC–Ln^II (NHC = N-heterocyclic carbene; Ln = Eu, Yb) complexes were obtained from the corresponding NHC–AgI. The lability of the NHC–Ln^II bond was investigated and treatment with CO₂ led to insertion reactions without oxidation of the metal centre. The Eu^II complex [EuI₂(IMes)(THF)₃] (IMes = 1,3-dimesitylimidazol-2-ylidene) exhibits photoluminescence with a quantum yield reaching 53%.