Bis-N-heterocyclic carbene 'pincer' ligands and iridium complexes with CF3 - Substituted phenylene backbone

With the aim to favour formation of 'pincer'-type Ir-III complexes containing two NHC donor moieties, we have used a pro-ligand with a bis-CF3-substituted phenylene backbone in order to prevent unwanted backbone cyclometallation. The potential of this new 'pincer' pro-ligand, 1,1'-(4,6-bis(trifluoromethyl)-1,3- phenylene) bis(3-butyl-1H-imidazol-3-ium) iodide (3), is demonstrated by the synthesis and structural characterisation of the 'pincer' Ir-III bis carbene benzenide complex (4). (C) 2014 Elsevier B.V. All rights reserved.