Zhu Ning

Channel of Electronic Interactions in Diferrocenyl Pyrrole Derivatives

2,5-Diferrocenyl-1-(3-trifluorom-ethylphenyl)-pyrrole (1), 2,5-diferrocenyl-1-(4-fluorophenyl)-pyrrole (2), 2,5-diferrocenyl-1-phenyl pyrrole (3), 2,5-diferro-cenyl-1-(4-ethylphenyl)-pyrrole (4), and 2,5-diferrocenyl1-(4-ethoxyphenyl)-pyrrole (5) were prepared by the one-pot cycloaddition reaction of ferrocenyl alkyne. The 2,5-diferrocenyl-1-phenyl-1-pyrrole derivatives were characterized by elemental analysis, Fourier-transform infrared (FTIR) spectroscopy, mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy. The influence of substituents at the phenyl moiety on the electronic interaction was studied using cyclic voltammetry (CV) and density functional theory (DFT) calculations. A linear relationship was observed between the first oxidation potential (Ea1), oxidation potential difference (ΔE) with Hammett constant (Hammett σ) of the substituent, pyrrole H NMR chemical shift (δ), and pyrrole N natural bond orbital (NBO) charge. A high N charge density weakened the electronic interaction, and vice versa. Electron transfer between the two ferrocenyl units of these diferrocenyl pyrrole derivatives was influenced by the N charge density.