Redox‐Switchable Complexes Based on Nanographene‐NHCs

A series of rhodium and iridium complexes with a N‐heterocyclic carbene (NHC) ligand decorated with a perylene‐diimide‐pyrene moiety are described. Electrochemical studies reveal that the complexes can undergo two successive one‐electron reduction events, associated to the reduction of the PDI moiety attached to the NHC ligand. The reduction of the ligand produces a significant increase on its electron‐donating character, as observed from the infrared spectroelectrochemical studies. The rhodium complex was tested in the [3+2] cycloaddition of diphenylcyclopropenone and methylphenylacetylene, where it displayed a redox‐switchable behavior. The neutral complex showed moderate activity, which was suppressed when the catalyst was reduced. A nanographene‐functionalized NHC ligand was prepared and coordinated to rhodium an iridium. The presence of a perylene‐diimide moiety in the ligand allows that the resulting complexes show redox‐switching properties in the [3+2] cycloaddition of diphenylcyclopropenone and methylphenylacetylene.