The next generation of C2-symmetric ligands: A di- N-heterocyclic carbene (NHC) ligand and the synthesis and X-ray characterization of mono- and dinuclear rhodium(I) and iridium(I) complexes

Abstract

A new C 2-symmetric chelating di- N-heterocyclic carbene (NHC) ligand is reported. The stable free di-carbene (+/−)[DEAM-BY] ( 3) forms upon treating the imidazolium salt (+/−)[DEAM-BI][OTf] 2 ( 2) with potassium bis-trimethylsilylamide (where DEAM-BY = trans-9,10-dihydro-9,10-ethanoanthracene-11,12- bis(1-benzyl)imidaz-2-ylidene and DEAM-BI = trans-9,10-dihydro-9,10-ethanoanthracene-11,12- bis(1-benzyl)imidazolium). Metalation reactions of 2 with [Rh(COD)Cl] 2 and [Ir(COD)Cl] 2 are carried out under mild conditions to produce either mono- or bimetallic complexes. Each compound is characterized by NMR spectroscopy, combustion analysis, and single-crystal X-ray crystallography.