So what happens is this carbon along with one electron that is present in this sigma bond, goes away and moves onto this carbon to form a sigma bond between this carbon and this carbon. At the same time, one of the electrons in this bond that is broken remains on this carbon number two. And so that is what we see in this diagram. So this carbon number two is this carbon shown in this diagram that contains this single electron. Now in the final step, we basically want to regenerate this vitamin B twelve group. And so what happens is one of these h ions along with one of the electrons moves on to form a sigma bond between this carbon and this h atom and we form this succinct coenzyme a.