Doubly N-Confused and Ring-Contracted [24]Hexaphyrin Pd-Complexes: Stable Antiaromatic N-Confused Expanded Porphyrins

Abstract Pd-catalyzed Suzuki-Miyaura coupling of 1,14-dibromotripyrrin produced doubly N-confused and ring-contracted (DNCRC) [24]hexaphyrin(1.1.0.1.1.0) mono- and bis-Pd-complexes as the first example of stable antiaromatic N-confused expanded porphyrins. These macrocycles show a paratropic ring currents, an ill-defined Soret band, a red-shifted weak absorption tail, and a small HOMO-LUMO gap. NBS bromination of the bis Pd-complex gave its mono- and dibromides regioselectively, which were effectively used to synthesize a DNCRC [24]hexaphyrin dimer and a NiII porphyrin-DNCRC [24]hexaphyrin-NiII porphyrin triad, respectively.