Unexpected formation of the nickel seco-tribenzoporphyrazine with a tribenzotetraazachlorin-type absorption spectrum.

Minor products in the reaction between substituted 1,3-diiminoisoindolines and 2,5-diamino-3,4-dicyanothiophene were identified as the nickel seco-tribenzoporphyrazines 4 and 5, which have been characterized by UV-vis, MCD, NMR, and mass spectroscopy. Experimentally observed tetraazachlorin-type UV-vis spectra of new seco-tribenzoporphyrazines were explained on the basis of DFT and TDDFT calculations.