2-Ferrocenyl-substituted pyrylium ions from coupling of ethynylferrocene with cyclomanganated chalcones

Abstract

2-Ferrocenyl-substituted pyrylium salts are produced when orthomanganated chalcones are reacted with ethynylferrocene in CCl4. When the reaction is carried out in benzene, intermediate ferrocenyl-substituted (η5-pyranyl)Mn(CO)3 species can be isolated which give the pyrylium cations on oxidation. The electrochemistry of the 2-ferrocenyl-pyrylium cations shows both oxidation (of the ferrocenyl) and reduction (of the pyrylium) processes, and the UV–visible spectra show a broad band at ca 680 nm which can be assigned to an intramolecular charge transfer transition.