5, 10, 15-Triferrocenylcorrole complexes

Complexes of 5,10,15-triferrocenylcorrole were
synthesized from the crude free-base corrole product obtained by
the reaction of ferrocenyl aldehyde and pyrrole. Direct formation of
the complex in this manner leads to an increase of the reaction yield
by protecting the corrole ring toward oxidative decomposition. The
procedure was successful and gave the expected product in the case
of the copper and triphenylphosphinecobalt complexes, but an
unexpected result was obtained in the case of the nickel derivative,
where metal insertion led to a ring opening of the macrocycle at the
5 position, giving as a final product a linear tetrapyrrole nickel
complex bearing two ferrocenyl groups. The purified 5,10,15-triferrocenylcorrole complexes have been fully characterized by a combination of spectroscopic methods, electrochemistry, spectroelectrochemistry, and density functional theory calculations. Copper derivatives of 10-monoferrocenyl- and 5,15-diferrocenylcorrole were prepared to investigate how the number and position of the ferrocenyl groups influenced the spectroscopic and electrochemical properties of the resulting complexes. A complete assignment of resonances in the 1H and 13C NMR spectra was performed for the cobalt and nickel complexes, and detailed electrochemical characterization was carried out to provide additional insight into the degree of communication between the meso-ferrocenyl groups on the conjugated macrocycle and the central metal ion of the ferrocenylcorrole derivatives.