Free-base corroles have long been known to be acidic, readily undergoing deprotonation by mild bases and in polar solvents. The conjugate base, however, has not been structurally characterized until now. Presented here is a first crystal structure of a freebase corrole anion, derived from tris(p-cyanophenyl)corrole, as the tetrabuylammonium salt. The low-temperature (100 K) structure reveals ...