Synthesis and electrochemistry property of new crowded multi-ferrocenyl substituted benzene derivatives

Abstract

A series of new sterically crowded multi-ferrocenyl and ferrocenylethynyl substituted benzene derivatives, 1,2,4-triferrocenyl-3,5-diferrocenylethynylbenzene (2), 1,3,5-triferrocenyl-2,4-diferrocenylethynylbenzene (3), 1-indenyl-2-trimethylsilyl-4,5-diferrocenyl-3,6-diferrocenylethynylbenzene (4), 1-indenyl-2-trimethylsilyl-4,6-diferrocenyl-3,5-diferrocenylethynylbenzene (5), 1-indenyl-2-trimethylsilyl-3,5-diferrocenyl-4,6-diferrocenylethynylbenzene (6) were synthesized by [2+2+2] cycloaddition reactions of 1,4-bis(ferrocenyl)butadiyne with cobalt clusters Co2(CO)6(μ2-η2-FcCCH) and Co2(CO)6(μ2-η2-C9H7CCSiMe3) (1) [where C9H7=indenyl, Fc=ferrocenyl, Me=methyl], and characterized by FT-IR, NMR, MS and elemental analysis. The crystal structures of compounds 1, 3–5 were determined by X-ray single crystal diffraction analysis for the first time.The electrochemical results of compounds 2–6 studied by cyclic voltammetry and square wave voltammetry indicate the wave splitting and the electronic interactions of 2–6 are related to the directly bonded ferrocenyl termini. Compounds 4–6 are three isomers, of which the molecular structures could be identified by their electrochemical properties and structural information.