β-octabromo-meso-tris(pentafluorophenyl)corrole: reductive demetalation-based synthesis of a heretofore inaccessible, perhalogenated free-base corrole

摘要

Long known in various metal-complexed forms, β-octabromo-meso-tris(pentafluorophenyl)corrole, H3[Br8TPFPC], has not been available as a free ligand until now. It can be prepared in high yield (86%) via reductive demetalation (conc. H2SO4, FeCl2) of Mn[Br8TPFPC]. Interestingly, the same conditions did not result in demetalation of the analogous copper complex, which may be contrasted to the behavior of many other copper corroles, which demetalate cleanly. X-ray crystallographic analysis revealed a unique "half-saddled" conformation, wherein two of the pyrrole rings on one side of the direct pyrrole-pyrrole linkage are strongly tilted up and down relative to each other, whereas the other two pyrrole rings are roughly in the mean plane of the macrocycle.