Synthesis and structural characterization of new multi-ferrocenyl pyridine derivatives

Abstract

A series of new multi-ferrocenyl substituted pyridine derivatives, 4,6-diferrocenyl-3,5-diferrocenylethynyl-2-methylpyridine (1), 3,6-diferrocenyl-4,5-diferrocenylethynyl-2-phenylpyridine (2), 4,6-diferrocenyl-3,5-diferrocenylethynyl-2-phenylpyridine (3), 3,5-diferrocenyl-4,6-diferrocenylethynyl-2-phenylpyridine (4) were synthesized by dicarbonylcyclopentadienylcobalt mediated [2+2+2] cycloaddition reaction. The molecular composition and structure of compounds 1–4 were characterized by FT-IR, NMR, MS, CV and Elemental analysis. The molecular and crystal structure of compound 1 was determined by X-ray single crystal diffraction analysis.The cyclic voltammetry and square wave voltammetry highlight the electrochemical behaviors of compounds 1–4, which indicates multi-step reversible redox processes of ferrocenyl moieties have occurred. The wave splitting and ΔE1/2 (oxidation potential difference) values of 1–4 were carefully analyzed, which reveals that the interactions between the ferrocenyl units of 1–4 are related to their molecular structures. The molecular structures of isomers 2–4 have been identified by their electrochemical properties and spectroscopic information.