<i>m</i>‐Benziporphyrin(1.1.0.0)s as a Rare Example of Ring‐Contracted Carbaporphyrins with Metal‐Coordination Ability: Distorted Coordination Structures and Small HOMO‐LUMO Gaps
Le Liu, Fenni Zhang, Ling Xu, Mingbo Zhou, Bangshao Yin, Takayuki Tanaka, Atsuhiro Osuka, Jianxin Song
Abstract
Abstract m ‐Benziporphyrin(1.1.0.0) and m ‐pyreniporphyrin(1.1.0.0) were prepared as ring‐contracted carbaporphyrins. While m ‐Benziporphyrin(1.1.0.0) was unstable, m ‐pyreniporphyrin(1.1.0.0) was fairly stable. Both of their Pd II complexes showed distorted coordination structures with extremely short Pd−C bonds. As compared with the reported m ‐benziporphyrin Pd II complexes, these Pd II complexes showed considerably small HOMO‐LUMO gaps, despite their smaller molecular size. Pd II metalation of the m ‐pyreniporphyrin(1.1.0.0) dimer gave the corresponding Pd II complex, which showed similar distorted coordination and a smaller HOMO‐LUMO gap. Finally, Pd II metalation of a pyrene‐sharing formal p ‐benziporphyrin(1.1.1.1) dimer gave a nonaromatic Pd II dimer, which rearranged to an aromatic Pd II complex upon treatment with alumina.