Complexes based on the redox-active pyrazinediimine ligands developed by our group can be functionalised at the distal pyrazine nitrogen atom, determining important changes in electronic structure. We have discovered that N-methylation of such systems followed by α-deprotonation, to give rise to a mesoionic NHC, where Fe is part of the ligand backbone. These NHCs are strong σ-donors and strong π-acceptors, and these properties can be further modulated by oxidation. The in-situ generated NHCs can add alcohols and amines (even sterically bulky amines such as HN(SiMe3)2) Complexation with noble metals (e.g. rhodium or iridium) gives rise to heterobimetallic complexes which are interesting and robust redox-switchable catalysts. This approach allowed us to obtain temporal control in catalysed hydrosilyation reactions. The new redox-switches differentiate considerably from the literature established ferrocene analogues, allowing the operation at significantly milder potentials. At the time of their publication, they were the only example of redox-switchable catalysts which utilise a metal-based redox-switch which is not based on metallocenes.