The corrole derivative meso-oxoisocorrole has been theoretically predicted to be antiaromatic, despite its formally cross conjugated electronic system. In this study, this prediction has been experimentally proven by the facile preparation of meso-oxoisocorrole via the oxidation of a meso free corrole with MnO2 and its comprehensive characterization using NMR, UV/vis absorption, FT-IR, and transient-absorption spectroscopy, cyclic voltammetry, and X-ray diffraction analysis. Furthermore, the free base meso-oxoisocorrole was metalated by treatment with Ni­(acac)2, PdCl2(PhCN)2, and Zn­(OAc)2 to give the corresponding metal complexes. These complexes are more strongly antiaromatic, and their degree of paratropicity depends on their planarity. Thus, fine tuning of their antiaromaticity was achieved with concomitant modulation of their HOMO–LUMO gaps. In the presence of tris­(pentafluorophenyl)­borane, their antiaromaticity is significantly enhanced due to the elongation of the CO bond, which promotes the polarized C+–O– resonance state. Furthermore, a distinct frequency shift of the CO vibrational mode in the triplet state was observed in the time-resolved IR spectra in accordance with the Baird rule, which indicates aromaticity reversal in the excited state.

3,7,23,octaphyrin 2 was synthesized as a novel octaphyrin bearing two meso-free positions. Surprisingly, its Zn II and Ni II complexation reactions produced a directly fused porphyrin(2.1.1.1) dimer 6, and a meso-a fused N-confused porphyrin (NCP) dimer 7, as the first example of NCP tape, respectively, via transannular C À C bond formation. While 6 exhibits a diatropic ring-current effect owing to the global 36p Mçbius aromaticity, 7 shows a paratropic ringcurrent effect due to the global Hückel 36p antiaromaticity. In addition, the oxidation of 7 with PbO 2 allowed for formation of its two-electron oxidized species 9 that exhibited a diatropic ring-current effect due to the global Hückel 34p aromaticity. This work has demonstrated that meso-free large expanded porphyrins can be a promising platform to produce novel fused porphyrinoids.

The synthesis of robust high-spin carbon radicals is an important topic in organic chemistry. Toward this end, several porphyrin-stabilized radicals have been systematically explored. A singly naphthalene-fused porphyrin radical was synthesized by a reaction sequence consisting of a Suzuki-Miyaura coupling of b-borylated porphyrin with 2-bromobenzaldehyde, addition of mesityl Grignard reagent, intramolecular Friedel-Crafts alkylation, and final oxidation with DDQ or tBuOK/O 2. This strategy was also used to synthesize doubly naphthalene-fused porphyrins and syn-and anti-fused-anthracene-bridged porphyrin dimers. While singly naphthalenefused porphyrin radical has been shown to be a stable monoradical, doubly naphthalene-fused porphyrins and antifused-anthracene-bridged porphyrin dimers have been shown to be closed-shell molecules. Finally, the syn-dimer was characterized as a surprisingly stable radical (t 1/2 = 28 days under ambient air and at 80 8C) that is storable for more than several months, despite its high-spin triplet ground-state carbon diradical.

Ruthenium(II) p-coordination onto [28]hexaphyrins(1.1.1.1.1.1) has been accomplished. Reactions of bis-Au III and mono-Au III complexes of hexakis(pentafluorophenyl) [28]hexaphyrin with [RuCl 2 (p-cymene)] 2 in the presence of NaOAc gave the corresponding p-ruthenium complexes,i n which the [(p-cymene)Ru] II fragment sat on the deprotonated side pyrrole.Asimilar reaction of the bis-Pd II [26]hexaphyrin complex afforded at riple-decker complex, in which the two [(p-cymene)Ru] II fragments sat on both sides of the center of the [26]hexaphyrin framework.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

μ-Oxo-bridged Si(iv) corrole dimers show dual emission behavior. Their conformational relaxation can be controlled by substituent bulkiness.