A synthesis of novel expanded porphyrinoids: NiII-induced nitrile cyclization of dicyanovinylene-bis(meso-aryl)dipyrrin†
NiII-Metallation of dicyanovinylene-bis(meso-aryl)dipyrrin 1 under refluxed toulene conditions resulted in the formation of a bicyclic pyrrolizine ring to afford two isomeric bisNiII expanded porphyrinoid complexes 2a and 2b. Furthermore, acyclic NiII dipyrrin complex 3 was also isolated. The respective structures for 2a, 2b, and 3 were elucidated by X-ray diffraction analysis. Macrocycles 2a and 2b exhibited typical features of aromatic porphyrinoids showing their longest wavelength absorption bands in the near infrared region ranging from 1100 to 1600 nm.