Abstract

The nickel(II) complex of meso-dimethylaminoprop-1-enyloctaethylporphyrin (2c) was converted by quaternization and thermolysis into a pair of novel isomeric macrocyclic complexes (3) and (4). These have a fused six-membered ring, and an exocyclic double bond on the neighbouring β-position, and have been named ‘australochlorins’. Heating these compounds in acetic acid leads to the known nickel(II) octaethylbenzochlorin (1) and a novel β-(1-acetoxyethyl)benzochlorin (5). Trifluoroacetic acid promotes the regioselective formation of benzochlorin/porphyrin species from the mononickel(II) complexes of the acrolein derivatives of bis(octaethylporphyrinyl)ethane and trans-ethene.