The treatment of an antiaromatic norcorrole Ni(II) complex with a kinetically stabilized silylene provided ring-expansion products in excellent yields through the highly regio- and stereoselective insertion into the β-β pyrrolic CC bonds. The resultant Ni(II) porphyrinoid monoinsertion product exhibited relatively strong near-IR absorption bands due to the small HOMO-LUMO gap in spite of the disrupted cyclic π-conjugation by the silicon atom.

Norcorrole is a ring-contracted porphyrinoid, exhibiting distinct antiaromaticity. Herein, we report the reactions of meso-dimesitylnorcorrole Ni­(II) complex with two types of carbenes: dichlorocarbene and an N-heterocyclic carbene (NHC). The reaction with in-situ-generated dichlorocarbene resulted in the double insertion of two chloromethine units to provide a mixture of 5,15-dichloroporphyrin and chlorinated isopyricorroles. The nucleophilic NHC attacked the 3-position of the norcorrole core and the subsequent proton transfer furnished a nonconjugated macrocycle incorporating a diazafulvene segment.

A chirality switch between novel NCN pincer Rh complexes and a related double cyclometalated NCNC Rh complex containing secondary amino groups is described.

The treatment of an antiaromatic norcorrole NiII complex with a kinetically stabilized silylene provided ring‐expansion products in excellent yields through the highly regio‐ and stereoselective insertion into the β‐β pyrrolic CC bonds. The resultant NiII porphyrinoid monoinsertion product exhibited relatively strong near‐IR absorption bands due to the small HOMO–LUMO gap in spite of the disrupted cyclic π‐conjugation by the silicon atom.