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‐meso‐triphenylcorrole (Cu[Br(8)TPC]) and β‐octakis(trifluoromethyl)‐meso‐tris(p‐methoxyphenyl)corrole (Cu[(CF(3))(8)TpOMePC]). Unlike reductive demetalation, which affords the free‐base β‐octabromocorrole, demetalation of Cu[Br(8)TPC] under non‐ reductive conditions (CHCl(3)/H(2)SO(4)) resulted in moderate yields of free‐base 5‐ and 10‐hydroxy isocorroles. The isomeric free bases could be complexed to Co(II) and Ni(II), affording stable complexes. Only reductive demetalation was found to work for Cu[(CF(3))(8)TpOMePC], affording a highly saddled, hydrated corrole, H(3)[5‐OH,10‐H‐(CF(3))(8)TpOMePC], where the elements of water had added across C(5) and C(10). Interaction of this novel free base with Co(II) resulted in Co[iso‐10‐H‐[CF(3))(8)TpOMePC], a Co(II) 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.