Tetrabromo[36]octaphyrin: A Promising Precursor of Directly Fused Porphyrin(2.1.1.1) Dimer and meso‐α Fused N‐Confused Porphyrin Dimer

Abstract

Abstract3,7,23,27‐Tetrabromo[36]octaphyrin 2 was synthesized as a novel octaphyrin bearing two meso‐free positions. Surprisingly, its ZnII and NiII complexation reactions produced a directly fused porphyrin(2.1.1.1) dimer 6, and a meso‐α fused N‐confused porphyrin (NCP) dimer 7, as the first example of NCP tape, respectively, via transannular C−C bond formation. While 6 exhibits a diatropic ring‐current effect owing to the global 36π Möbius aromaticity, 7 shows a paratropic ring‐current effect due to the global Hückel 36π antiaromaticity. In addition, the oxidation of 7 with PbO2 allowed for formation of its two‐electron oxidized species 9 that exhibited a diatropic ring‐current effect due to the global Hückel 34π aromaticity. This work has demonstrated that meso‐free large expanded porphyrins can be a promising platform to produce novel fused porphyrinoids.