Iridium(III) Complexes Bearing Chelating Bis-NHC Ligands and Their Application in the Catalytic Reduction of Imines

Aznarez, Francisco ; Iglesias, Manuel (Universidad de Zaragoza) ; Hepp, Alexander ; Veit, Benjamin ; Sanz Miguel, Pablo J. (Universidad de Zaragoza) ; Oro, Luis A. (Universidad de Zaragoza) ; Jin, Guoxin ; Hahn, F.Ekkehardt

Resumen: The IrIII complexes 4 and 5 bearing bis-NHC ligands (NHC = N-heterocyclic carbene) composed of one classical NR,NR NHC and one N,NR NHC donor were prepared by the reaction of the azolium/azole compounds 2I and 3Br, respectively, with [{Cp*IrCl(µ-Cl)}2] (Cp*=¿5-C5Me5) in the presence of NaOAc as base. Most likely, the salts 2I and 3Br were first selectively deprotonated at the C2 position of the disubstituted (NR,NR) diazaheterocycle to generate an NHC donor, which then coordinated to the IrIII center. Subsequently, NaOAc promoted C–H bond activation at the pendant imidazole moiety of the intermediate IrIII mono-NHC complexes led to the formation of the six-membered iridacycles 4 and 5, which bear a chelating, doubly C-metalated C(NHC)^C(NHC') bis-NHC ligand. The IrIII complexes 4 and 5 were tested as precatalysts for the reduction of imines with molecular hydrogen. Moderate to good activity was observed at a catalyst loading of 5 mol-% and an H2 pressure of 3 bar in MeOH.

Idioma: Inglés

DOI: 10.1002/ejic.201600922

Año: 2016

Publicado en: EUROPEAN JOURNAL OF INORGANIC CHEMISTRY 2016, 28 (2016), 4598-4603
ISSN: 1434-1948

Factor impacto JCR: 2.444 (2016)

Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 13 / 46 = 0.283 (2016) - Q2 - T1

Factor impacto SCIMAGO: 0.837 - Inorganic Chemistry (Q1)

Tipo y forma: Artículo (PostPrint)

Área (Departamento): Área Química Inorgánica (Dpto. Química Inorgánica)