Fused benzene rings to antiaromatic compounds generally improve their stability but attenuate their antiaromaticity. The opposite case is now reported. NiII benzonorcorroles were synthesized and the effect of benzo-fusion on the antiaromaticity was elucidated. The benzo-fusion resulted in significant decrease of the HOMO–LUMO gaps and enhancement of the paratropic ring current effect. Furthermore, the introduction of the benzo groups induced singlet diradical character in the antiaromatic porphyrinoid.
Bibliographical noteFunding Information:
This work was supported by JSPS KAKENHI grants JP26102003 (H.S.), JP15K21721 (H.S.), and JP17H05157 (M.N.), as well as by the Program for Leading Graduate Schools “Integrative Graduate Education and Research in Green Natural Sciences” from MEXT. T.Y. expresses his gratitude for a JSPS Research Fellowship for Young Scientists (JP16J10315). H.S. gratefully acknowledges the Murata Science Foundation for financial support. Work at the Yonsei University was supported by the Global Research Laboratory (2013K1A1A2A02050183) funded by the Ministry of Science, ICT and Future Planning.
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