Synthesis of 2,5-diferrocenyl five-membered heterocyclic compounds and their electrochemistry

Abstract

A series of 2,5-diferrocenyl substituted five-membered heterocyclic compounds, 2,5-diferrocenyl-1-phenylpyrrole (1), 2,5-diferrocenyl-1-(4-fluorophenyl)-pyrrole (2), 2,5-diferrocenyl-1-(4-ethoxyphenyl)-pyrrole (3), 2,5-diferrocenyl-1-(4-ethylphenyl)-pyrrole (4), 2,5-diferrocenylthiophene (5), and 2,5-diferrocenylfuran (6), were synthesized using one-pot cycloaddition of ferrocenyl alkyne and characterized by elemental analysis, FT-IR, MS, and NMR. The molecular structures of 1, 2, 5, and 6 were determined using single-crystal X-ray diffraction. Electronic communication between two ferrocenyl units of 1–6 was investigated using cyclic voltammetry. These compounds have two well-resolved electrochemically reversible one-electron-transfer processes using [NBu4][PF6] as the supporting electrolyte. The electrochemical studies reveal that electronic communication between two ferrocenyl units depend on the heteroatoms.