β-Octabromo- and β-Octakis(trifluoromethyl)isocorroles: New Sterically Constrained Macrocyclic Ligands.

Presented herein is a study of the acid-induced demetalation of two sterically hindered copper corroles, Cu β-octabromo--triphenylcorrole (Cu[BrTPC]) and β-octakis(trifluoromethyl)--tris(-methoxyphenyl)corrole (Cu[(CF)TOMePC]). Unlike reductive demetalation, which affords the free-base β-octabromocorrole, demetalation of Cu[BrTPC] under non- reductive conditions (CHCl/HSO) resulted in moderate yields of free-base 5- and 10-hydroxy isocorroles. The isomeric free bases could be complexed to Co and Ni, affording stable complexes. Only reductive demetalation was found to work for Cu[(CF)TOMePC], affording a highly saddled, hydrated corrole, H[5-OH,10-H-(CF)TOMePC], where the elements of water had added across C and C. Interaction of this novel free base with Co resulted in Co[-10-H-[CF)TOMePC], a Co 10-hydro isocorrole. The new metal complexes were all characterized by single-crystal X-ray diffraction analysis and, despite their sterically hindered nature, were found to exhibit almost perfectly planar isocorrole cores.