Di(p‐dibenzi)[40]decaphyrin(1.0.0.0.0.1.0.0.0.0) PdII Complex: A Weakly Hückel 38π‐Aromatic Macrocycle

Abstract

AbstractDi(p‐benzi)[40]decaphyrin(1.0.0.0.0.1.0.0.0.0) BF2 complex and tris(p‐benzi)[60]pentadecaphyrin(1.0.0.0.0.1.0.0.0.0.1.0.0.0.0) BF2 complex were synthesized by Suzuki‐Miyaura coupling of α,α’‐diborylated tetrapyrrole BF2‐complex with 1,4‐diiodobenzene. Bis‐BF2 complex was converted to bis‐PdII complex via its free base. Macrocycles bis‐BF2 and tris‐BF2 complex take Möbius topology but are nonaromatic, since the macrocyclic conjugation is disrupted by the locally aromatic 1,4‐phenylene units. In contrast, bis‐PdII complex is a weakly Hückel 38π‐aromatic macrocycle as evinced by its red‐shifted, enhanced, and structured Q‐like bands and a small electrochemical HOMO‐LUMO gap. Interestingly, one 1,4‐pheylene part of bis‐PdII complex takes a quinonoidal distorted structure and the other takes a usual benzene structure in a figure‐eight conformation with Hückel topology.