Crystalline Cyclic (Alkyl)(amino)carbene-tetrafluoropyridyl Radical.

A stable cyclic (alkyl)(amino)carbene (CAAC) 1 inserts into the para-CF bond of pentafluoropyridine, and after fluoride abstraction, the iminium-pyridyl adduct 3 was isolated. A cyclic voltammetry study shows a reversible three-state redox system involving 3 , 3 , and 3 . The CAAC-pyridyl radical 3 , obtained by reduction of 3 with magnesium, has been spectroscopically and crystallographically characterized. In contrast to the lack of π communication between the CAAC and the pyridine units in cation 3 , the unpaired electron of 3 is delocalized over an extended π system involving both heterocycles.