Tetraphenylbenziporphyrin - A ligand for organometallic chemistry

Abstract

6,11,16,21-Tetraphenylbenziporphyrin (TPBPH)H, an analogue of tetraphenylporphyrin with one of the pyrrole groups replaced by a benzene ring, is formed in good yield in the condensation of the appropriate precursor with pyrrole and benzaldehyde. (TPBPH)H gives organometallic complexes with palladium(II) and platinum(II), [(TPBP)PdII] and [(TPBP)PtII], in which the metal ion is bound in the macrocyclic cavity by three pyrrolic nitrogen atoms and a carbon atom of the benzene ring. In the reaction with silver(I) acetate benziporphyrin does not yield a stable complex but undergoes selective acetoxylation at the internal carbon atom. (TPBPH)H is reversibly reduced to 6-benziphlorin and reacts with a water or methanol molecule to give 6-hydroxy- or 6-methoxy-6-benziphlorin, respectively.