Unsymmetrical cyrhetrenyl and ferrocenyl azines derived from 5-nitrofurane: Synthesis, structural characterization and electrochemistry

Abstract

A new series of unsymmetrical cyrhetrenyl and ferrocenyl azines that were monosubstituted [(η5-C5H4)– C(R)_N–N_CH(5-NO2–2-C4H2O)]M {with M_Re(CO)3 and R_H (1a) or R_Me (1b); M_Fe(η5-C5H5) and R_H (2a) or R_Me (2b)} and disubstituted [Fe{(η5-C5H4)–C(Me)_N–N_CH(5-NO2–2-C4H2O)}2] (3a) were prepared by condensation reactions of the corresponding organometallic hydrazone [(η5-C5H4)–C(R)_N– NH2)]M with 5-nitro-2-furaldehyde. The 1H and 13C{1H} NMR spectra indicated that these compounds adopted an (E,E)-configuration about the ˃C_N− bond and an s-trans conformation about the N1–N2 bond, and this resultwas confirmed by X-ray crystallographic analyses of 1a and 2b. The opposite electronic effects of the organometallic fragments correlate with the co-planarity of the [(η5-C5H4)–C(R)_N–N_CH(5-NO2–2-C4H2O)] system, the reduction potential of the nitro group (E1/2) and the chemical shifts of the iminic carbons