Reversible 1/1 2+ redox system. Reversible two-electron redox processes are the hallmark of transition metal catalysis. In stark contrast, main group p-block compounds rarely exhibit such processes . Having established that bis(imino)carbene 1 can undergo a two-electron oxidation sequence to carbene dication 1 2+ (Fig. ), we set out to explore the reverse two-electron reduction by employing a similar two-step strategy. We reasoned that this could be achieved by first employing H -as the two-electron reductant, then removing H + and leaving behind two electrons. Accordingly, subjecting 1 2+ to H3B•NEt3 afforded the protonated bis(imino)carbene, which could be deprotonated by K[N(SiMe3)2], leading to the successful regeneration of 1. Hence, 1/1 2+ constitutes an unprecedented reversible twoelectron redox system between a carbene and its dication . More importantly, this is a further demonstration that 1 2+ behaves as a doubly oxidized carbene.