m‐Pyripentaphyrins(1.0.0.0.0): BIII Complexes and β‐β Directly Linked Dimers

Abstract m‐Pyripentaphyrins(1.0.0.0.0) were synthesized by Suzuki‐Miyaura coupling of 3,5‐bis(5‐borylpyrrol‐2‐yl)‐BODIPY with 2,6‐dibromopyridine. Upon treatment with PhBCl 2 , pyripentaphyrin 1 provided mono‐ and bis‐B III complexes sequentially. The Mono‐B III complex shows a distorted tetrahedral coordinated B III with a σ‐phenyl ligand on the B III and the bis‐B III complex shows an additional distorted tetrahedral coordinated B III with a B−H bond. Bromination of the pyripentaphyrins with N‐bromosuccinimide (NBS) resulted in regioselective formation of 8‐bromopyripentaphyrins, which were dimerized to 8,8’‐linked dimers by reductive coupling with Ni(cod) 2 . While all these pyripentaphyrins are nonaromatic, they exhibit characteristic broad absorption bands at long wavelength near the NIR region, indicating the presence of effective macrocyclic conjugation.