Redox Activity of Ir III Complexes with Multidentate Ligands Based on Dipyrido‐Annulated N ‐Heterocyclic Carbenes: Access to High Valent and High Spin State with Carbon Donors

Synthetic strategies to access high‐valent iridium complexes usually require use of π donating ligands bearing electronegative atoms (e. g. amide or oxide) or σ donating electropositive atoms (e. g. boryl or hydride). Besides the η 5 ‐(methyl)cyclopentadienyl derivatives, high‐valent η 1 carbon‐ligated iridium complexes are challenging to synthesize. To meet this challenge, this work reports the oxidation behavior of an all‐carbon‐ligated anionic bis( CCC‐ pincer) Ir III complex. Being both σ and π donating, the diaryl dipyrido‐annulated N ‐heterocyclic carbene (dpa‐NHC) Ir III complex allowed a stepwise 4e − oxidation sequence. The first 2e − oxidation led to an oxidative coupling of two adjacent aryl groups, resulting in formation of a cationic chiral Ir III complex bearing a CCCC‐tetradentate ligand. A further 2e − oxidation allowed isolation of a high‐valent tricationic complex with a triplet ground state. These results close a synthetic gap for carbon‐ligated iridium complexes and demonstrate the electronic tuning potential of organic π ligands for unusual electronic properties.